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• Unexpected results for projection on to plane

  - by ravenspoint

  I want to use this projection matrix: GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; It should cast object shadows onto the y = 0 plane from a point light at 1,1,-1. I create a rectangle in the x = 0.5 plane glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); Now if I manually multiply these vertices with the matrix, I get. glBegin( GL_QUADS ); glVertex3f( 0.375,0,-0.375); glVertex3f( 0.375,0,-1.625); glVertex3f( 0,0,-2); glVertex3f( 0,0,0); glEnd(); Which produces a reasonable display ( camera at 0,5,0 looking down y axis ) So rather than do the calculation manually, I should be able to use the opengl model transormation. I write this code: glMatrixMode (GL_MODELVIEW); GLfloat shadow[] = { -1,0,0,0, 1,0,-1,1, 0,0,-1,0, 0,0,0,-1 }; glLoadMatrixf( shadow ); glBegin( GL_QUADS ); glVertex3f( 0.5,0.2,-0.5); glVertex3f( 0.5,0.2,-1.5); glVertex3f( 0.5,0.5,-1.5); glVertex3f( 0.5,0.5,-0.5); glEnd(); But this produces a blank screen! What am I doing wrong? Is there some debug mode where I can print out the transformed vertices, so I can see where they are ending up? Note: People have suggested that using glMultMatrixf() might make a difference. It doesn't. Replacing glLoadMatrixf( shadow ); with glLoadIdentity(); glMultMatrixf( shadow ); gives the identical result ( of course! )

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• Euler angles to Cartesian Coordinates for use with gluLookAt

  - by notrodash

  I have searched all of the internet but just couldn't find the answer. I am using LibGDX and this is part of my code that loops over and over: public void render() { GL11 gl = Gdx.gl11; float centerX = (float)Math.cos(yaw) * (float)Math.cos(pitch); float centerY = (float)Math.sin(yaw) * (float)Math.cos(pitch); float centerZ = (float)Math.sin(pitch); System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z); Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0); if(Gdx.input.isKeyPressed(Keys.A)) { yaw--; } if(Gdx.input.isKeyPressed(Keys.D)) { yaw++; } } I might just be bad at the math, but I dont get it. Does someone have a good explanation and an idea about how to deal with this? I am trying to make a first person camera. By the way, the camera is translated by +10 on the Z axis. Currently when I run the application, this is what I get: Watch video in browser | Download video (for those who cant download the video, everything shakes in a clockwise/anticlockwise action, depending on if I increase or decrease the Yaw value) -Thank you. [edit] and with this code: public void render() { GL11 gl = Gdx.gl11; float centerX = (float)(MathUtils.cosDeg(yaw)*4); float centerY = 0; float centerZ = (float)(MathUtils.sinDeg(yaw)*4); System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z); Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0); if(Gdx.input.isKeyPressed(Keys.A)) { yaw--; } if(Gdx.input.isKeyPressed(Keys.D)) { yaw++; } } it slowly swings from the left to the right. This approach worked for turning left and right for 2d games though. What am I doing wrong?

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• How to detect which edges of a rectange touch when they collide in iOS

  - by Mike King

  I'm creating a basic "game" in iOS 4.1. The premise is simple, there is a green rectangle ("disk") that moves/bounces around the screen, and red rectangle ("bump") that is stationary. The user can move the red "bump" by touching another coordinate on the screen, but that's irrelevant to this question. Each rectangle is a UIImageView (I will replace them with some kind of image/icon once I get the mechanics down). I've gotten as far as detecting when the rectangles collide, and I'm able to reverse the direction of the green "disk" on the Y axis if they do. This works well when the green "disk" approaches the red "bump" from top or bottom, it bounces off in the other direction. But when it approaches from the side, the bounce is incorrect; I need to reverse the X direction instead. Here's the timer I setup: - (void)viewDidLoad { xSpeed = 3; ySpeed = -3; gameTimer = [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(mainGameLoop:) userInfo:nil repeats:YES]; [super viewDidLoad]; } Here's the main game loop: - (void) mainGameLoop:(NSTimer *)theTimer { disk.center = CGPointMake(disk.center.x + xSpeed, disk.center.y + ySpeed); // make sure the disk does not travel off the edges of the screen // magic number values based on size of disk's frame // startAnimating causes the image to "pulse" if (disk.center.x < 55 || disk.center.x > 265) { xSpeed = xSpeed * -1; [disk startAnimating]; } if (disk.center.y < 55 || disk.center.y > 360) { ySpeed = ySpeed * -1; [disk startAnimating]; } // check to see if the disk collides with the bump if (CGRectIntersectsRect(disk.frame, bump.frame)) { NSLog(@"Collision detected..."); if (! [disk isAnimating]) { ySpeed = ySpeed * -1; [disk startAnimating]; } } } So my question is: how can I detect whether I need to flip the X speed or the Y speed? ie: how can I calculate which edge of the bump was collided with?

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• Incorrect results for frustum cull

  - by DeadMG

  Previously, I had a problem with my frustum culling producing too optimistic results- that is, including many objects that were not in the view volume. Now I have refactored that code and produced a cull that should be accurate to the actual frustum, instead of an axis-aligned box approximation. The problem is that now it never returns anything to be in the view volume. As the mathematical support library I'm using does not provide plane support functions, I had to code much of this functionality myself, and I'm not really the mathematical type, so it's likely that I've made some silly error somewhere. As follows is the relevant code: class Plane { public: Plane() { r0 = Math::Vector(0,0,0); normal = Math::Vector(0,1,0); } Plane(Math::Vector p1, Math::Vector p2, Math::Vector p3) { r0 = p1; normal = Math::Cross((p2 - p1), (p3 - p1)); } Math::Vector r0; Math::Vector normal; }; This class represents one plane as a point and a normal vector. class Frustum { public: Frustum( const std::array<Math::Vector, 8>& points ) { planes[0] = Plane(points[0], points[1], points[2]); planes[1] = Plane(points[4], points[5], points[6]); planes[2] = Plane(points[0], points[1], points[4]); planes[3] = Plane(points[2], points[3], points[6]); planes[4] = Plane(points[0], points[2], points[4]); planes[5] = Plane(points[1], points[3], points[5]); } Plane planes[6]; }; The points are passed in order where (the inverse of) each bit of the index of each point indicates whether it's the left, top, and back of the frustum, respectively. As such, I just picked any three points where they all shared one bit in common to define the planes. My intersection test is as follows (based on this): bool Intersects(Math::AABB lhs, const Frustum& rhs) const { for(int i = 0; i < 6; i++) { Math::Vector pvertex = lhs.TopRightFurthest; Math::Vector nvertex = lhs.BottomLeftClosest; if (rhs.planes[i].normal.x <= -0.0f) { std::swap(pvertex.x, nvertex.x); } if (rhs.planes[i].normal.y <= -0.0f) { std::swap(pvertex.y, nvertex.y); } if (rhs.planes[i].normal.z <= -0.0f) { std::swap(pvertex.z, nvertex.z); } if (Math::Dot(rhs.planes[i].r0, nvertex) < 0.0f) { return false; } } return true; } Also of note is that because I'm using a left-handed co-ordinate system, I wrote my Cross function to return the negative of the formula given on Wikipedia. Any suggestions as to where I've made a mistake?

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• Why does my ID3DXSprite appear to be incorrectly scaled?

  - by Bjoern

  I am using D3D9 for rendering some simple things (a movie) as the backmost layer, then on top of that some text messages, and now wanted to add some buttons to that. Before adding the buttons everything seemed to have worked fine, and I was using a ID3DXSprite for the text as well (ID3DXFont), now I am loading some graphics for the buttons, but they seem to be scaled to something like 1.2 times their original size. In my test window I centered the graphic, but it being too big it just doesnt fit well, for example the client area is 640x360, the graphic is 440, so I expect 100 pixel on left and right, left side is fine [I took screenshot and "counted" the pixels in photoshop], but on the right there is only about 20 pixels) My rendering code is very simple (I am omitting error checks, et cetera, for brevity) // initially viewport was set to width/height of client area // clear device m_d3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET|D3DCLEAR_STENCIL|D3DCLEAR_ZBUFFER, D3DCOLOR_ARGB(0,0,0,0), 1.0f, 0 ); // begin scene m_d3dDevice->BeginScene(); // render movie surface (just two triangles to which the movie is rendered) m_d3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE,false); m_d3dDevice->SetSamplerState( 0, D3DSAMP_MAGFILTER, D3DTEXF_LINEAR ); // bilinear filtering m_d3dDevice->SetSamplerState( 0, D3DSAMP_MINFILTER, D3DTEXF_LINEAR ); // bilinear filtering m_d3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE ); m_d3dDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE ); //Ignored m_d3dDevice->SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_SELECTARG1 ); m_d3dDevice->SetTexture( 0, m_movieTexture ); m_d3dDevice->SetStreamSource(0, m_displayPlaneVertexBuffer, 0, sizeof(Vertex)); m_d3dDevice->SetFVF(Vertex::FVF_Flags); m_d3dDevice->DrawPrimitive(D3DPT_TRIANGLELIST, 0, 2); // render sprites m_sprite->Begin(D3DXSPRITE_ALPHABLEND | D3DXSPRITE_SORT_TEXTURE | D3DXSPRITE_DO_NOT_ADDREF_TEXTURE); // text drop shadow m_font->DrawText( m_playerSprite, m_currentMessage.c_str(), m_currentMessage.size(), &m_playerFontRectDropShadow, DT_RIGHT|DT_TOP|DT_NOCLIP, m_playerFontColorDropShadow ); // text m_font->DrawText( m_playerSprite, m_currentMessage.c_str(), m_currentMessage.size(), &m_playerFontRect, DT_RIGHT|DT_TOP|DT_NOCLIP, m_playerFontColorMessage ) ); // control object m_sprite->Draw( m_texture, 0, 0, &m_vecPos, 0xFFFFFFFF ); // draws a few objects like this m_sprite->End() // end scene m_d3dDevice->EndScene(); What did I forget to do here? Except for the control objects (play button, pause button etc which are placed on a "panel" which is about 440 pixels wide) everything seems fine, the objects are positioned where I expect them, but just too big. By the way I loaded the images using D3DXCreateTextureFromFileEx (resizing wnidow, and reacting to lost device, etc, works fine too). For experimenting, I added some code to take an identity matrix and scale is down on the x/y axis to 0.75f, which then gave me the expected result for the controls (but also made the text smaller and out of position), but I don't know why I would need to scale anything. My rendering code is so simple, I just wanted to draw my 2D objects 1;1 the size they came from the file... I am really very inexperienced in D3D, so the answer might be very simple...

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• Any ideas on reducing lag in terrain generation?

  - by l5p4ngl312

  Ok so here's the deal. I've written an isometric engine that generates terrain based on camera values using 2D perlin noise. I planned on doing 3D but first I need to work out the lag issues I'm having. I will try to explain how I am doing this so that maybe someone can spot where I am going wrong. I know it should not be this laggy. There is the abstract class Block which right now just contains render(). BlockGrass, etc. extend this class and each has code in the render function to create a textured quad at the given position. Then there is the class Chunk which has the function Generate() and setBlocksInArea(). Generate uses 2D perlin noise to make a height map and stores the heights in a 2D array. It stores the positions of each block it generates in blockarray[x][y][z]. The chunks are 8x8x128. In the main game class there is a 3D array called blocksInArea. The blocks in this array are what gets rendered. When a chunk generates, it adds its blocks to this array at the correct index. It is like this so chunks can be saved to the hard drive (even though they aren't yet) but there can still be optimization with the rendering that you wouldn't have if you rendered each chunk separately. Here's where the laggy part comes in: When the camera moves to a new chunk, a row of chunks generates on the end of the axis that the camera moved on. But it still has to move the other chunks up/down in the blocksInArea (render) array. It does this by calculating the new position in the array and doing the Chunk.setBlocksInArea(): for(int x = 0; x < 8; x++){ for(int y = 0; y < 8; y++){ nx = x+(coordX - camCoordX)*8 ny = y+(coordY - camCoordY)*8 for(int z = 0; z < height[x][y]; z++){ blockarray[x][y][z] = Game.blocksInArea[nx][ny][z]; } } } My reasoning was that this would be much faster than doing the perlin noise all over again, but there are still little spikes of lag when you move in between chunks. Edit: Would it be possible to create a 3 dimensional array list so that shifting of chunks within the array would not be neccessary?

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• OpenGL ES 2 jittery camera movement

  - by user16547

  First of all, I am aware that there's no camera in OpenGL (ES 2), but from my understanding proper manipulation of the projection matrix can simulate the concept of a camera. What I'm trying to do is make my camera follow my character. My game is 2D, btw. I think the principle is the following (take Super Mario Bros or Doodle Jump as reference - actually I'm trying to replicate the mechanics of the latter): when the caracter goes beyond the center of the screen (in the positive axis/direction), update the camera to be centred on the character. Else keep the camera still. I did accomplish that, however the camera movement is noticeably jittery and I ran out of ideas how to make it smoother. First of all, my game loop (following this article): private int TICKS_PER_SECOND = 30; private int SKIP_TICKS = 1000 / TICKS_PER_SECOND; private int MAX_FRAMESKIP = 5; @Override public void run() { loops = 0; if(firstLoop) { nextGameTick = SystemClock.elapsedRealtime(); firstLoop = false; } while(SystemClock.elapsedRealtime() > nextGameTick && loops < MAX_FRAMESKIP) { step(); nextGameTick += SKIP_TICKS; loops++; } interpolation = ( SystemClock.elapsedRealtime() + SKIP_TICKS - nextGameTick ) / (float)SKIP_TICKS; draw(); } And the following code deals with moving the camera. I was unsure whether to place it in step() or draw(), but it doesn't make a difference to my problem at the moment, as I tried both and neither seemed to fix it. center just represents the y coordinate of the centre of the screen at any time. Initially it is 0. The camera object is my own custom "camera" which basically is a class that just manipulates the view and projection matrices. if(character.getVerticalSpeed() >= 0) { //only update camera if going up float[] projectionMatrix = camera.getProjectionMatrix(); if( character.getY() > center) { center += character.getVerticalSpeed(); cameraBottom = center + camera.getBottom(); cameraTop = center + camera.getTop(); Matrix.orthoM(projectionMatrix, 0, camera.getLeft(), camera.getRight(), center + camera.getBottom(), center + camera.getTop(), camera.getNear(), camera.getFar()); } } Any thought about what I should try or what I am doing wrong? Update 1: I think I updated every value you can see on screen to check whether the jittery movement is affected by that, but nothing changed, so something must be fundamentally flawed with my approach/calculations.

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• glTranslate, how exactly does it work?

  - by mykk

  I have some trouble understanding how does glTranslate work. At first I thought it would just simply add values to axis to do the transformation. However then I have created two objects that would load bitmaps, one has matrix set to GL_TEXTURE: public class Background { float[] vertices = new float[] { 0f, -1f, 0.0f, 4f, -1f, 0.0f, 0f, 1f, 0.0f, 4f, 1f, 0.0f }; .... private float backgroundScrolled = 0; public void scrollBackground(GL10 gl) { gl.glLoadIdentity(); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glTranslatef(0f, 0f, 0f); gl.glPushMatrix(); gl.glLoadIdentity(); gl.glMatrixMode(GL10.GL_TEXTURE); gl.glTranslatef(backgroundScrolled, 0.0f, 0.0f); gl.glPushMatrix(); this.draw(gl); gl.glPopMatrix(); backgroundScrolled += 0.01f; gl.glLoadIdentity(); } } and another to GL_MODELVIEW: public class Box { float[] vertices = new float[] { 0.5f, 0f, 0.0f, 1f, 0f, 0.0f, 0.5f, 0.5f, 0.0f, 1f, 0.5f, 0.0f }; .... private float boxScrolled = 0; public void scrollBackground(GL10 gl) { gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glTranslatef(0f, 0f, 0f); gl.glPushMatrix(); gl.glMatrixMode(GL10.GL_MODELVIEW); gl.glLoadIdentity(); gl.glTranslatef(boxScrolled, 0.0f, 0.0f); gl.glPushMatrix(); this.draw(gl); gl.glPopMatrix(); boxScrolled+= 0.01f; gl.glLoadIdentity(); } } Now they are both drawn in Renderer.OnDraw. However background moves exactly 5 times faster. If I multiply boxScrolled by 5 they will be in sinc and will move together. If I modify backgrounds vertices to be float[] vertices = new float[] { 1f, -1f, 0.0f, 0f, -1f, 0.0f, 1f, 1f, 0.0f, 0f, 1f, 0.0f }; It will also be in sinc with the box. So, what is going under glTranslate?

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• How do I randomly generate a top-down 2D level with separate sections and is infinite?

  - by Bagofsheep

  I've read many other questions/answers about random level generation but most of them deal with either randomly/proceduraly generating 2D levels viewed from the side or 3D levels. What I'm trying to achieve is sort of like you were looking straight down on a Minecraft map. There is no height, but the borders of each "biome" or "section" of the map are random and varied. I already have basic code that can generate a perfectly square level with the same tileset (randomly picking segments from the tileset image), but I've encountered a major issue for wanting the level to be infinite: Beyond a certain point, the tiles' positions become negative on one or both of the axis. The code I use to only draw tiles the player can see relies on taking the tiles position and converting it to the index number that represents it in the array. As you well know, arrays cannot have a negative index. Here is some of my code: This generates the square (or rectangle) of tiles: //Scale is in tiles public void Generate(int sX, int sY) { scaleX = sX; scaleY = sY; for (int y = 0; y <= scaleY; y++) { tiles.Add(new List<Tile>()); for (int x = 0; x <= scaleX; x++) { tiles[tiles.Count - 1].Add(tileset.randomTile(x * tileset.TileSize, y * tileset.TileSize)); } } } Before I changed the code after realizing an array index couldn't be negative my for loops looked something like this to center the map around (0, 0): for (int y = -scaleY / 2; y <= scaleY / 2; y++) for (int x = -scaleX / 2; x <= scaleX / 2; x++) Here is the code that draws the tiles: int startX = (int)Math.Floor((player.Position.X - (graphics.Viewport.Width) - tileset.TileSize) / tileset.TileSize); int endX = (int)Math.Ceiling((player.Position.X + (graphics.Viewport.Width) + tileset.TileSize) / tileset.TileSize); int startY = (int)Math.Floor((player.Position.Y - (graphics.Viewport.Height) - tileset.TileSize) / tileset.TileSize); int endY = (int)Math.Ceiling((player.Position.Y + (graphics.Viewport.Height) + tileset.TileSize) / tileset.TileSize); for (int y = startY; y < endY; y++) { for (int x = startX; x < endX; x++) { if (x >= 0 && y >= 0 && x <= scaleX && y <= scaleY) tiles[y][x].Draw(spriteBatch); } } So to summarize what I'm asking: First, how do I randomly generate a top-down 2D map with different sections (not chunks per se, but areas with different tile sets) and second, how do I get past this negative array index issue?

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• 2D collision resolving

  - by Philippe Paré

  I've just worked out an AABB collision algorithm for my 2D game and I was very satisfied until I found out it only works properly with movements of 1 in X and 1 in Y... here it is: public bool Intersects(Rectanglef rectangle) { return this.Left < rectangle.Right && this.Right > rectangle.Left && this.Top < rectangle.Bottom && this.Bottom > rectangle.Top; } public bool IntersectsAny(params Rectanglef[] rectangles) { for (int i = 0; i < rectangles.Length; i++) { if (this.Left < rectangles[i].Right && this.Right > rectangles[i].Left && this.Top < rectangles[i].Bottom && this.Bottom > rectangles[i].Top) return true; } return false; } and here is how I use it in the update function of my player : public void Update(GameTime gameTime) { Rectanglef nextPosX = new Rectanglef(AABB.X, AABB.Y, AABB.Width, AABB.Height); Rectanglef nextPosY; if (Input.Key(Key.Left)) nextPosX.X--; if (Input.Key(Key.Right)) nextPosX.X++; bool xFree = !nextPosX.IntersectsAny(Boxes.ToArray()); if (xFree) nextPosY = new Rectanglef(nextPosX.X, nextPosX.Y, nextPosX.Width, nextPosX.Height); else nextPosY = new Rectanglef(AABB.X, AABB.Y, AABB.Width, AABB.Height); if (Input.Key(Key.Up)) nextPosY.Y--; if (Input.Key(Key.Down)) nextPosY.Y++; bool yFree = !nextPosY.IntersectsAny(Boxes.ToArray()); if (yFree) AABB = nextPosY; else if (xFree) AABB = nextPosX; } What I'm having trouble with, is a system where I can give float values to my movement and make it so there's a smooth acceleration. Do I have to retrieve the collision rectangle (the rectangle created by the other two colliding)? or should I do some sort of vector and go along this axis until I reach the collision? Thanks a lot!

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• How do I make camera move at same speed when rotating and moving forward

  - by dez

  I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want. However, if I hold down Up and move the mouse at the same time then the camera moves a lot faster than it should. I want it to move at the same speed as it does when only the Up arrow is pressed. I think I need to normalize something somewhere but not sure what and not sure where. Have tried various combinations without success so if anyone can point me in the right direction that would be great. Thanks. I've post code below. #define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam ) { if( KEY_DOWN(VK_UP)) MovePlayer(D3DXVECTOR3(0, 0, -1.0f)); if( KEY_DOWN(VK_DOWN)) MovePlayer(D3DXVECTOR3(0, 0, 1.0f)); switch( msg ) { case WM_MOUSEMOVE: ProcessMouseInput(); } } void MovePlayer( D3DXVECTOR3 in_vec ) { D3DXMATRIX CameraRot; D3DXMatrixRotationY(&CameraRot,D3DXToRadian(AngleY)); D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&in_vec,&CameraRot); CameraPos += (m_timeElapsed * CameraRotTarget); } void ProcessMouseInput() { GetCursorPos( &CurrentMouseState ); if ((CurrentMouseState.x != GameMouseState.x) || (CurrentMouseState.y != GameMouseState.y)) { int dx = CurrentMouseState.x - GameMouseState.x; int dy = CurrentMouseState.y - GameMouseState.y; AngleY+=m_timeElapsed*dx*7.0f; } GameMouseState = CurrentMouseState; // Set back to window center in Render function } VOID UpdateCamera() { D3DXVECTOR3 CameraOrigTarget(0, 0, -1); D3DXVECTOR3 CameraOrigUp(0, 1, 0); D3DXMATRIX CameraRot; D3DXMATRIX CameraRotX; D3DXMatrixRotationX(&CameraRotX,D3DXToRadian(AngleX)); D3DXMATRIX CameraRotY; D3DXMatrixRotationY(&CameraRotY,D3DXToRadian(AngleY)); CameraRot = CameraRotX * CameraRotY; D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&CameraOrigTarget,&CameraRot); D3DXVECTOR3 CameraTarget; CameraTarget = CameraPos + CameraRotTarget; D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f ); D3DXMatrixLookAtLH( &matView, &CameraPos, &CameraTarget, &vUpVec ); g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView ); D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI / 4, 1.0f, 1.0f, 100.0f ); g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj ); }

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• Physics Engine [Collision Response, 2-dimensional] experts, help!! My stack is unstable!

  - by Register Sole

  Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they hardly stand still! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have: I would try adding a damping term (proportional to velocity) to the Baumgarte. Is this a good idea in general? If not I would not want to waste my time trying to tune the parameter hoping it magically works. Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :)

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• Where i set touch effect when a spawn Srite are comming on the screen?

  - by shihab_returns

  I just create a scene where create a spawn spirit that comes from above screen height in Landscape mode. Now i want to remove spirits when i touch on it. I tried but seems the code not works and crashed also after a while. here is my code: /** TimerHandler for collision detection and cleaning up */ IUpdateHandler detect = new IUpdateHandler() { @Override public void reset() { } @Override public void onUpdate(float pSecondsElapsed) { Iterator<AnimatedSprite> targets = targetLL.iterator(); AnimatedSprite _target; while (targets.hasNext()) { _target = targets.next(); if (_target.getY() >= cameraHeight) { // removeSprite(_target, targets); tPool.recyclePoolItem(_target); targets.remove(); Log.d("ok", "---------Looop Inside-----"); // fail(); break; } } targetLL.addAll(TargetsToBeAdded); TargetsToBeAdded.clear(); } }; /** adds a target at a random location and let it move along the y-axis */ public void addTarget() { Random rand = new Random(); int minX = mTargetTextureRegion.getWidth(); int maxX = (int) (mCamera.getWidth() - mTargetTextureRegion.getWidth()); int rangeX = maxX - minX; Log.d("----point----", "minX:" + minX + "maxX:" + maxX + "rangeX:" + rangeX); int rX = rand.nextInt(rangeX) + minX; int rY = (int) mCamera.getHeight() + mTargetTextureRegion.getHeight(); Log.d("---Random x----", "Random x" + rX + "Random y" + rY); target = tPool.obtainPoolItem(); target.setPosition(rX, rY); target.animate(100); mMainScene.attachChild(target, 1); mMainScene.registerTouchArea(target); int minDuration = 2; int maxDuration = 32; int rangeDuration = maxDuration - minDuration; int actualDuration = rand.nextInt(rangeDuration) + minDuration; // MoveXModifier mod = new MoveXModifier(actualDuration, target.getX(), // -target.getWidth()); MoveYModifier mody = new MoveYModifier(actualDuration, -target.getHeight(), cameraHeight + 10); target.registerEntityModifier(mody.deepCopy()); TargetsToBeAdded.add(target); } @Override public boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final ITouchArea pTouchArea, final float pTouchAreaLocalX, final float pTouchAreaLocalY) { if (pTouchArea == target) { Toast.makeText(getApplicationContext(), "Yoooooooo", Toast.LENGTH_LONG).show(); } return true; } ** My question is where i implements IOnAreaTouchListener in My code. ? ** Thanks in Advance.

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• XNA 4.0: 2D Camera Y and X are going in wrong direction

  - by Setheron

  I asked this question on stackoverflow but assumed this might be a better area to ask it as well for a more informed answer. My problem is that I am trying to create a camera class and have it so that my camera follows the proper RHS, however the Y axis seems to be inverted since on the screen the 0 starts at the top. Here is my Camera2D Class: class Camera2D { private Vector2 _position; private float _zoom; private float _rotation; private float _cameraSpeed; private Viewport _viewport; private Matrix _viewMatrix; private Matrix _viewMatrixIverse; public static float MinZoom = float.Epsilon; public static float MaxZoom = float.MaxValue; public Camera2D(Viewport viewport) { _viewMatrix = Matrix.Identity; _viewport = viewport; _cameraSpeed = 4.0f; _zoom = 1.0f; _rotation = 0.0f; _position = Vector2.Zero; } public void Move(Vector2 amount) { _position += amount; } public void Zoom(float amount) { _zoom += amount; _zoom = MathHelper.Clamp(_zoom, MaxZoom, MinZoom); UpdateViewTransform(); } public Vector2 Position { get { return _position; } set { _position = value; UpdateViewTransform(); } } public Matrix ViewMatrix { get { return _viewMatrix; } } private void UpdateViewTransform() { Matrix proj = Matrix.CreateTranslation(new Vector3(_viewport.Width * 0.5f, _viewport.Height * 0.5f, 0)) * Matrix.CreateScale(new Vector3(1f, 1f, 1f)); _viewMatrix = Matrix.CreateRotationZ(_rotation) * Matrix.CreateScale(new Vector3(_zoom, _zoom, 1.0f)) * Matrix.CreateTranslation(_position.X, _position.Y, 0.0f); _viewMatrix = proj * _viewMatrix; } } I test it using SpriteBatch in the following way: protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); Vector2 position = new Vector2(0, 0); // TODO: Add your drawing code here spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.AlphaBlend, null, null, null, null, camera.ViewMatrix); Texture2D circle = CreateCircle(100); spriteBatch.Draw(circle, position, Color.Red); spriteBatch.End(); base.Draw(gameTime); }

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• Camera not working

  - by user17548

  I made a camera in DX9. To move forward I press the Up arrow. To rotate on the Y axis I use the mouse. When I perform these movements on their own the camera moves at the speed I want. However, if I hold down Up and move the mouse at the same time then the camera moves a lot faster than it should. I want it to move at the same speed as it does when only the Up arrow is pressed. I think I need to normalize something somewhere but not sure what and not sure where. Have tried various combinations without success so if anyone can point me in the right direction that would be great. Thanks. My code #define KEY_DOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam ) { if( KEY_DOWN(VK_UP)) MovePlayer(D3DXVECTOR3(0, 0, -1.0f)); if( KEY_DOWN(VK_DOWN)) MovePlayer(D3DXVECTOR3(0, 0, 1.0f)); switch( msg ) { case WM_MOUSEMOVE: ProcessMouseInput(); } } void MovePlayer( D3DXVECTOR3 in_vec ) { D3DXMATRIX CameraRot; D3DXMatrixRotationY(&CameraRot,D3DXToRadian(AngleY)); D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&in_vec,&CameraRot); CameraPos += (m_timeElapsed * CameraRotTarget); } void ProcessMouseInput() { GetCursorPos( &CurrentMouseState ); if ((CurrentMouseState.x != GameMouseState.x) || (CurrentMouseState.y != GameMouseState.y)) { int dx = CurrentMouseState.x - GameMouseState.x; int dy = CurrentMouseState.y - GameMouseState.y; AngleY+=m_timeElapsed*dx*7.0f; } GameMouseState = CurrentMouseState; // Set back to window center in Render function } VOID UpdateCamera() { D3DXVECTOR3 CameraOrigTarget(0, 0, -1); D3DXVECTOR3 CameraOrigUp(0, 1, 0); D3DXMATRIX CameraRot; D3DXMATRIX CameraRotX; D3DXMatrixRotationX(&CameraRotX,D3DXToRadian(AngleX)); D3DXMATRIX CameraRotY; D3DXMatrixRotationY(&CameraRotY,D3DXToRadian(AngleY)); CameraRot = CameraRotX * CameraRotY; D3DXVECTOR3 CameraRotTarget; D3DXVec3TransformNormal(&CameraRotTarget,&CameraOrigTarget,&CameraRot); D3DXVECTOR3 CameraTarget; CameraTarget = CameraPos + CameraRotTarget; D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f ); D3DXMatrixLookAtLH( &matView, &CameraPos, &CameraTarget, &vUpVec ); g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView ); D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI / 4, 1.0f, 1.0f, 100.0f ); g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj ); }

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• Inverse Kinematics with OpenGL/Eigen3 : unstable jacobian pseudoinverse

  - by SigTerm

  I'm trying to implement simple inverse kinematics test using OpenGL, Eigen3 and "jacobian pseudoinverse" method. The system works fine using "jacobian transpose" algorithm, however, as soon as I attempt to use "pseudoinverse", joints become unstable and start jerking around (eventually they freeze completely - unless I use "jacobian transpose" fallback computation). I've investigated the issue and turns out that in some cases jacobian.inverse()*jacobian has zero determinant and cannot be inverted. However, I've seen other demos on the internet (youtube) that claim to use same method and they do not seem to have this problem. So I'm uncertain where is the cause of the issue. Code is attached below: *.h: struct Ik{ float targetAngle; float ikLength; VectorXf angles; Vector3f root, target; Vector3f jointPos(int ikIndex); size_t size() const; Vector3f getEndPos(int index, const VectorXf& vec); void resize(size_t size); void update(float t); void render(); Ik(): targetAngle(0), ikLength(10){ } }; *.cpp: size_t Ik::size() const{ return angles.rows(); } Vector3f Ik::getEndPos(int index, const VectorXf& vec){ Vector3f pos(0, 0, 0); while(true){ Eigen::Affine3f t; float radAngle = pi*vec[index]/180.0f; t = Eigen::AngleAxisf(radAngle, Vector3f(-1, 0, 0)) * Eigen::Translation3f(Vector3f(0, 0, ikLength)); pos = t * pos; if (index == 0) break; index--; } return pos; } void Ik::resize(size_t size){ angles.resize(size); angles.setZero(); } void drawMarker(Vector3f p){ glBegin(GL_LINES); glVertex3f(p[0]-1, p[1], p[2]); glVertex3f(p[0]+1, p[1], p[2]); glVertex3f(p[0], p[1]-1, p[2]); glVertex3f(p[0], p[1]+1, p[2]); glVertex3f(p[0], p[1], p[2]-1); glVertex3f(p[0], p[1], p[2]+1); glEnd(); } void drawIkArm(float length){ glBegin(GL_LINES); float f = 0.25f; glVertex3f(0, 0, length); glVertex3f(-f, -f, 0); glVertex3f(0, 0, length); glVertex3f(f, -f, 0); glVertex3f(0, 0, length); glVertex3f(f, f, 0); glVertex3f(0, 0, length); glVertex3f(-f, f, 0); glEnd(); glBegin(GL_LINE_LOOP); glVertex3f(f, f, 0); glVertex3f(-f, f, 0); glVertex3f(-f, -f, 0); glVertex3f(f, -f, 0); glEnd(); } void Ik::update(float t){ targetAngle += t * pi*2.0f/10.0f; while (t > pi*2.0f) t -= pi*2.0f; target << 0, 8 + 3*sinf(targetAngle), cosf(targetAngle)*4.0f+5.0f; Vector3f tmpTarget = target; Vector3f targetDiff = tmpTarget - root; float l = targetDiff.norm(); float maxLen = ikLength*(float)angles.size() - 0.01f; if (l > maxLen){ targetDiff *= maxLen/l; l = targetDiff.norm(); tmpTarget = root + targetDiff; } Vector3f endPos = getEndPos(size()-1, angles); Vector3f diff = tmpTarget - endPos; float maxAngle = 360.0f/(float)angles.size(); for(int loop = 0; loop < 1; loop++){ MatrixXf jacobian(diff.rows(), angles.rows()); jacobian.setZero(); float step = 1.0f; for (int i = 0; i < angles.size(); i++){ Vector3f curRoot = root; if (i) curRoot = getEndPos(i-1, angles); Vector3f axis(1, 0, 0); Vector3f n = endPos - curRoot; float l = n.norm(); if (l) n /= l; n = n.cross(axis); if (l) n *= l*step*pi/180.0f; //std::cout << n << "\n"; for (int j = 0; j < 3; j++) jacobian(j, i) = n[j]; } std::cout << jacobian << std::endl; MatrixXf jjt = jacobian.transpose()*jacobian; //std::cout << jjt << std::endl; float d = jjt.determinant(); MatrixXf invJ; float scale = 0.1f; if (!d /*|| true*/){ invJ = jacobian.transpose(); scale = 5.0f; std::cout << "fallback to jacobian transpose!\n"; } else{ invJ = jjt.inverse()*jacobian.transpose(); std::cout << "jacobian pseudo-inverse!\n"; } //std::cout << invJ << std::endl; VectorXf add = invJ*diff*step*scale; //std::cout << add << std::endl; float maxSpeed = 15.0f; for (int i = 0; i < add.size(); i++){ float& cur = add[i]; cur = std::max(-maxSpeed, std::min(maxSpeed, cur)); } angles += add; for (int i = 0; i < angles.size(); i++){ float& cur = angles[i]; if (i) cur = std::max(-maxAngle, std::min(maxAngle, cur)); } } } void Ik::render(){ glPushMatrix(); glTranslatef(root[0], root[1], root[2]); for (int i = 0; i < angles.size(); i++){ glRotatef(angles[i], -1, 0, 0); drawIkArm(ikLength); glTranslatef(0, 0, ikLength); } glPopMatrix(); drawMarker(target); for (int i = 0; i < angles.size(); i++) drawMarker(getEndPos(i, angles)); } Any help will be appreciated.

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• Why is this class re-initialized every time?

  - by pinnacler

  I have 4 files and the code 'works' as expected. I try to clean everything up, place code into functions, etc... and everything looks fine... and it doesn't work. Can somebody please explain why MatLab is so quirky... or am I just stupid? Normally, I type terminator = simulation(100,20,0,0,0,1); terminator.animate(); and it should produce a map of trees with the terminator walking around in a forest. Everything rotates to his perspective. When I break it into functions... everything ceases to work. I really only changed a few lines of code, shown in comments. Code that works: classdef simulation properties landmarks robot end methods function obj = simulation(mapSize, trees, x,y,heading,velocity) obj.landmarks = landmarks(mapSize, trees); obj.robot = robot(x,y,heading,velocity); end function animate(obj) %Setup Plots fig=figure; xlabel('meters'), ylabel('meters') set(fig, 'name', 'Phil''s AWESOME 80''s Robot Simulator') xymax = obj.landmarks.mapSize*3; xymin = -(obj.landmarks.mapSize*3); l=scatter([0],[0],'bo'); axis([xymin xymax xymin xymax]); obj.landmarks.apparentPositions %Simulation Loop THIS WAS ORGANIZED for n = 1:720, %Calculate and Set Heading/Location obj.robot.headingChange = navigate(n); %Update Position obj.robot.heading = obj.robot.heading + obj.robot.headingChange; obj.landmarks.heading = obj.robot.heading; y = cosd(obj.robot.heading); x = sind(obj.robot.heading); obj.robot.x = obj.robot.x + (x*obj.robot.velocity); obj.robot.y = obj.robot.y + (y*obj.robot.velocity); obj.landmarks.x = obj.robot.x; obj.landmarks.y = obj.robot.y; %Animate set(l,'XData',obj.landmarks.apparentPositions(:,1),'YData',obj.landmarks.apparentPositions(:,2)); rectangle('Position',[-2,-2,4,4]); drawnow end end end end ----------- classdef landmarks properties fixedPositions %# positions in a fixed coordinate system. [ x, y ] mapSize = 10; %Map Size. Value is side of square x=0; y=0; heading=0; headingChange=0; end properties (Dependent) apparentPositions end methods function obj = landmarks(mapSize, numberOfTrees) obj.mapSize = mapSize; obj.fixedPositions = obj.mapSize * rand([numberOfTrees, 2]) .* sign(rand([numberOfTrees, 2]) - 0.5); end function apparent = get.apparentPositions(obj) %-STILL ROTATES AROUND ORIGINAL ORIGIN currentPosition = [obj.x ; obj.y]; apparent = bsxfun(@minus,(obj.fixedPositions)',currentPosition)'; apparent = ([cosd(obj.heading) -sind(obj.heading) ; sind(obj.heading) cosd(obj.heading)] * (apparent)')'; end end end ---------- classdef robot properties x y heading velocity headingChange end methods function obj = robot(x,y,heading,velocity) obj.x = x; obj.y = y; obj.heading = heading; obj.velocity = velocity; end end end ---------- function headingChange = navigate(n) %steeringChange = 5 * rand(1) * sign(rand(1) - 0.5); Most chaotic shit %Draw an S if n <270 headingChange=1; elseif n<540 headingChange=-1; elseif n<720 headingChange=1; else headingChange=1; end end Code that does not work... classdef simulation properties landmarks robot end methods function obj = simulation(mapSize, trees, x,y,heading,velocity) obj.landmarks = landmarks(mapSize, trees); obj.robot = robot(x,y,heading,velocity); end function animate(obj) %Setup Plots fig=figure; xlabel('meters'), ylabel('meters') set(fig, 'name', 'Phil''s AWESOME 80''s Robot Simulator') xymax = obj.landmarks.mapSize*3; xymin = -(obj.landmarks.mapSize*3); l=scatter([0],[0],'bo'); axis([xymin xymax xymin xymax]); obj.landmarks.apparentPositions %Simulation Loop for n = 1:720, %Calculate and Set Heading/Location %Update Position headingChange = navigate(n); obj.robot.updatePosition(headingChange); obj.landmarks.updatePerspective(obj.robot.heading, obj.robot.x, obj.robot.y); %Animate set(l,'XData',obj.landmarks.apparentPositions(:,1),'YData',obj.landmarks.apparentPositions(:,2)); rectangle('Position',[-2,-2,4,4]); drawnow end end end end ----------------- classdef landmarks properties fixedPositions; %# positions in a fixed coordinate system. [ x, y ] mapSize; %Map Size. Value is side of square x; y; heading; headingChange; end properties (Dependent) apparentPositions end methods function obj = createLandmarks(mapSize, numberOfTrees) obj.mapSize = mapSize; obj.fixedPositions = obj.mapSize * rand([numberOfTrees, 2]) .* sign(rand([numberOfTrees, 2]) - 0.5); end function apparent = get.apparentPositions(obj) %-STILL ROTATES AROUND ORIGINAL ORIGIN currentPosition = [obj.x ; obj.y]; apparent = bsxfun(@minus,(obj.fixedPositions)',currentPosition)'; apparent = ([cosd(obj.heading) -sind(obj.heading) ; sind(obj.heading) cosd(obj.heading)] * (apparent)')'; end function updatePerspective(obj,tempHeading,tempX,tempY) obj.heading = tempHeading; obj.x = tempX; obj.y = tempY; end end end ----------------- classdef robot properties x y heading velocity end methods function obj = robot(x,y,heading,velocity) obj.x = x; obj.y = y; obj.heading = heading; obj.velocity = velocity; end function updatePosition(obj,headingChange) obj.heading = obj.heading + headingChange; tempy = cosd(obj.heading); tempx = sind(obj.heading); obj.x = obj.x + (tempx*obj.velocity); obj.y = obj.y + (tempy*obj.velocity); end end end The navigate function is the same... I would appreciate any help as to why things aren't working. All I did was take the code from the first section from under comment: %Simulation Loop THIS WAS ORGANIZED and break it into 2 functions. One in robot and one in landmarks. Is a new instance created every time because it's constantly printing the same heading for this line int he robot class obj.heading = obj.heading + headingChange;

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• Laptop authentication/logon via accelerometer tilt, flip, and twist

  - by wonsungi

  Looking for another application/technology: A number of years ago, I read about a novel way to authenticate and log on to a laptop. The user simply had to hold the laptop in the air and execute a simple series of tilts and flips to the laptop. By logging accelerometer data, this creates a unique signature for the user. Even if an attacker watched and repeated the exact same motions, the attacker could not replicate the user's movements closely enough. I am looking for information about this technology again, but I can't find anything. It may have been an actual feature on a laptop, or it may have just been a research project. I think I read about it in a magazine like Wired. Does anyone have more information about authentication via unique accelerometer signatures? Here are the closest articles I have been able to find: Knock-based commands for your Linux laptop Shake Well Before Use: Authentication Based on Accelerometer Data[PDF] Inferring Identity using Accelerometers in Television Remote Controls User Evaluation of Lightweight User Authentication with a Single Tri-Axis Accelerometer Identifying Users of Portable Devices from Gait Pattern with Accelerometers[PDF] 3D Signature Biometrics Using Curvature Moments[PDF] MoViSign: A novel authentication mechanism using mobile virtual signatures

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• How do I implement AABB ray cast hit checking for opengl es on the iPhone

  - by Big Fizzy

  Basically, I draw a 3D cube, I can spin it around but I want to be able to touch it and know where on my cube's surface the user touched. I'm using for setting up, generating and spinning. Its based on the Molecules code and NeHe tutorial #5. Any help, links, tutorials and code would be greatly appreciated. I have lots of development experience but nothing much in the way of openGL and 3d. // // GLViewController.h // NeHe Lesson 05 // // Created by Jeff LaMarche on 12/12/08. // Copyright Jeff LaMarche Consulting 2008. All rights reserved. // #import "GLViewController.h" #import "GLView.h" @implementation GLViewController - (void)drawBox { static const GLfloat cubeVertices[] = { -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,-1.0f, 1.0f, -1.0f,-1.0f, 1.0f, -1.0f, 1.0f,-1.0f, 1.0f, 1.0f,-1.0f, 1.0f,-1.0f,-1.0f, -1.0f,-1.0f,-1.0f }; static const GLubyte cubeNumberOfIndices = 36; const GLubyte cubeVertexFaces[] = { 0, 1, 5, // Half of top face 0, 5, 4, // Other half of top face 4, 6, 5, // Half of front face 4, 6, 7, // Other half of front face 0, 1, 2, // Half of back face 0, 3, 2, // Other half of back face 1, 2, 5, // Half of right face 2, 5, 6, // Other half of right face 0, 3, 4, // Half of left face 7, 4, 3, // Other half of left face 3, 6, 2, // Half of bottom face 6, 7, 3, // Other half of bottom face }; const GLubyte cubeFaceColors[] = { 0, 255, 0, 255, 255, 125, 0, 255, 255, 0, 0, 255, 255, 255, 0, 255, 0, 0, 255, 255, 255, 0, 255, 255 }; glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, cubeVertices); int colorIndex = 0; for(int i = 0; i < cubeNumberOfIndices; i += 3) { glColor4ub(cubeFaceColors[colorIndex], cubeFaceColors[colorIndex+1], cubeFaceColors[colorIndex+2], cubeFaceColors[colorIndex+3]); int face = (i / 3.0); if (face%2 != 0.0) colorIndex+=4; glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, &cubeVertexFaces[i]); } glDisableClientState(GL_VERTEX_ARRAY); } //move this to a data model later! - (GLfixed)floatToFixed:(GLfloat)aValue; { return (GLfixed) (aValue * 65536.0f); } - (void)drawViewByRotatingAroundX:(float)xRotation rotatingAroundY:(float)yRotation scaling:(float)scaleFactor translationInX:(float)xTranslation translationInY:(float)yTranslation view:(GLView*)view; { glMatrixMode(GL_MODELVIEW); GLfixed currentModelViewMatrix[16] = { 45146, 47441, 2485, 0, -25149, 26775,-54274, 0, -40303, 36435, 36650, 0, 0, 0, 0, 65536 }; /* GLfixed currentModelViewMatrix[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 65536 }; */ //glLoadIdentity(); //glOrthof(-1.0f, 1.0f, -1.5f, 1.5f, -10.0f, 4.0f); // Reset rotation system if (isFirstDrawing) { //glLoadIdentity(); glMultMatrixx(currentModelViewMatrix); [self configureLighting]; isFirstDrawing = NO; } // Scale the view to fit current multitouch scaling GLfixed fixedPointScaleFactor = [self floatToFixed:scaleFactor]; glScalex(fixedPointScaleFactor, fixedPointScaleFactor, fixedPointScaleFactor); // Perform incremental rotation based on current angles in X and Y glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix); GLfloat totalRotation = sqrt(xRotation*xRotation + yRotation*yRotation); glRotatex([self floatToFixed:totalRotation], (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[1] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[0]), (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[5] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[4]), (GLfixed)((xRotation/totalRotation) * (GLfloat)currentModelViewMatrix[9] + (yRotation/totalRotation) * (GLfloat)currentModelViewMatrix[8]) ); // Translate the model by the accumulated amount glGetFixedv(GL_MODELVIEW_MATRIX, currentModelViewMatrix); float currentScaleFactor = sqrt(pow((GLfloat)currentModelViewMatrix[0] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[1] / 65536.0f, 2.0f) + pow((GLfloat)currentModelViewMatrix[2] / 65536.0f, 2.0f)); xTranslation = xTranslation / (currentScaleFactor * currentScaleFactor); yTranslation = yTranslation / (currentScaleFactor * currentScaleFactor); // Grab the current model matrix, and use the (0,4,8) components to figure the eye's X axis in the model coordinate system, translate along that glTranslatef(xTranslation * (GLfloat)currentModelViewMatrix[0] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[4] / 65536.0f, xTranslation * (GLfloat)currentModelViewMatrix[8] / 65536.0f); // Grab the current model matrix, and use the (1,5,9) components to figure the eye's Y axis in the model coordinate system, translate along that glTranslatef(yTranslation * (GLfloat)currentModelViewMatrix[1] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[5] / 65536.0f, yTranslation * (GLfloat)currentModelViewMatrix[9] / 65536.0f); // Black background, with depth buffer enabled glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); [self drawBox]; } - (void)configureLighting; { const GLfixed lightAmbient[] = {13107, 13107, 13107, 65535}; const GLfixed lightDiffuse[] = {65535, 65535, 65535, 65535}; const GLfixed matAmbient[] = {65535, 65535, 65535, 65535}; const GLfixed matDiffuse[] = {65535, 65535, 65535, 65535}; const GLfixed lightPosition[] = {30535, -30535, 0, 0}; const GLfixed lightShininess = 20; glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_COLOR_MATERIAL); glMaterialxv(GL_FRONT_AND_BACK, GL_AMBIENT, matAmbient); glMaterialxv(GL_FRONT_AND_BACK, GL_DIFFUSE, matDiffuse); glMaterialx(GL_FRONT_AND_BACK, GL_SHININESS, lightShininess); glLightxv(GL_LIGHT0, GL_AMBIENT, lightAmbient); glLightxv(GL_LIGHT0, GL_DIFFUSE, lightDiffuse); glLightxv(GL_LIGHT0, GL_POSITION, lightPosition); glEnable(GL_DEPTH_TEST); glShadeModel(GL_SMOOTH); glEnable(GL_NORMALIZE); } -(void)setupView:(GLView*)view { const GLfloat zNear = 0.1, zFar = 1000.0, fieldOfView = 60.0; GLfloat size; glMatrixMode(GL_PROJECTION); glEnable(GL_DEPTH_TEST); size = zNear * tanf(DEGREES_TO_RADIANS(fieldOfView) / 2.0); CGRect rect = view.bounds; glFrustumf(-size, size, -size / (rect.size.width / rect.size.height), size / (rect.size.width / rect.size.height), zNear, zFar); glViewport(0, 0, rect.size.width, rect.size.height); glScissor(0, 0, rect.size.width, rect.size.height); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glClearColor(0.0f, 0.0f, 0.0f, 1.0f); glTranslatef(0.0f, 0.0f, -6.0f); isFirstDrawing = YES; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; } - (void)dealloc { [super dealloc]; } @end

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• Laptop authentication/logon via accelometer tilt, flip, and twist

  - by wonsungi

  Looking for another application/technology: A number of years ago, I read about a novel way to authenticate and log on to a laptop. The user simply had to hold the laptop in the air and execute a simple series of tilts and flips to the laptop. By logging accelerometer data, this creates a unique signature for the user. Even if an attacker watched and repeated the exact same motions, the attacker could not replicate the user's movements closely enough. I am looking for information about this technology again, but I can't find anything. It may have been an actual feature on a laptop, or it may have just been a research project. I think I read about it in a magazine like Wired. Does anyone have more information about authentication via unique accelerometer signatures? Here are the closest articles I have been able to find: Knock-based commands for your Linux laptop Shake Well Before Use: Authentication Based on Accelerometer Data[PDF] Inferring Identity using Accelerometers in Television Remote Controls User Evaluation of Lightweight User Authentication with a Single Tri-Axis Accelerometer Identifying Users of Portable Devices from Gait Pattern with Accelerometers[PDF] 3D Signature Biometrics Using Curvature Moments[PDF] MoViSign: A novel authentication mechanism using mobile virtual signatures

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• Easily Plotting Multiple Data Series in Excel

  - by John

  I really need help figuring out how to speed up graphing multiple series on a graph. I have seperate devices that give monthly readings for several variables like pressure, temperature, and salinity. Each of these variables is going to be its own graph with devices being the series. My x-axis is going to be the dates that these values were taken. The problem is that it takes ages to do this for each spreadsheet since I have monthly dates from 1950 up to the present and I have about 50 devices in each spreadsheet. I also have graphs for calculated values that are in columns next to them. Each of these devices is going to become a data series in the graph. E.g. In one of my graphs I have all the pressures from the devices and each of the data series' names is the name of the device. I want a fast way to do this. Doing this manually is taking a very long time. Please help! Is there any easier way to do this? It is consistent and the dates all line up. I am just repeating the same clicks over and over again Thank you!

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• Using R to Analyze G1GC Log Files

  - by user12620111

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  Using R to Analyze G1GC Log Files   Using R to Analyze G1GC Log Files Introduction Working in Oracle Platform Integration gives an engineer opportunities to work on a wide array of technologies. My team’s goal is to make Oracle applications run best on the Solaris/SPARC platform. When looking for bottlenecks in a modern applications, one needs to be aware of not only how the CPUs and operating system are executing, but also network, storage, and in some cases, the Java Virtual Machine. I was recently presented with about 1.5 GB of Java Garbage First Garbage Collector log file data. If you’re not familiar with the subject, you might want to review Garbage First Garbage Collector Tuning by Monica Beckwith. The customer had been running Java HotSpot 1.6.0_31 to host a web application server. I was told that the Solaris/SPARC server was running a Java process launched using a commmand line that included the following flags: -d64 -Xms9g -Xmx9g -XX:+UseG1GC -XX:MaxGCPauseMillis=200 -XX:InitiatingHeapOccupancyPercent=80 -XX:PermSize=256m -XX:MaxPermSize=256m -XX:+PrintGC -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGC -XX:+PrintGCDateStamps -XX:+PrintFlagsFinal -XX:+DisableExplicitGC -XX:+UnlockExperimentalVMOptions -XX:ParallelGCThreads=8 Several sources on the internet indicate that if I were to print out the 1.5 GB of log files, it would require enough paper to fill the bed of a pick up truck. Of course, it would be fruitless to try to scan the log files by hand. Tools will be required to summarize the contents of the log files. Others have encountered large Java garbage collection log files. There are existing tools to analyze the log files: IBM’s GC toolkit The chewiebug GCViewer gchisto HPjmeter Instead of using one of the other tools listed, I decide to parse the log files with standard Unix tools, and analyze the data with R. Data Cleansing The log files arrived in two different formats. I guess that the difference is that one set of log files was generated using a more verbose option, maybe -XX:+PrintHeapAtGC, and the other set of log files was generated without that option. Format 1 In some of the log files, the log files with the less verbose format, a single trace, i.e. the report of a singe garbage collection event, looks like this: {Heap before GC invocations=12280 (full 61): garbage-first heap total 9437184K, used 7499918K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 1 young (4096K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. 2014-05-14T07:24:00.988-0700: 60586.353: [GC pause (young) 7324M->7320M(9216M), 0.1567265 secs] Heap after GC invocations=12281 (full 61): garbage-first heap total 9437184K, used 7496533K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) region size 4096K, 0 young (0K), 0 survivors (0K) compacting perm gen total 262144K, used 144077K [0xffffffff40000000, 0xffffffff50000000, 0xffffffff50000000) the space 262144K, 54% used [0xffffffff40000000, 0xffffffff48cb3758, 0xffffffff48cb3800, 0xffffffff50000000) No shared spaces configured. } A simple grep can be used to extract a summary: $ grep "\[ GC pause (young" g1gc.log 2014-05-13T13:24:35.091-0700: 3.109: [GC pause (young) 20M->5029K(9216M), 0.0146328 secs] 2014-05-13T13:24:35.440-0700: 3.459: [GC pause (young) 9125K->6077K(9216M), 0.0086723 secs] 2014-05-13T13:24:37.581-0700: 5.599: [GC pause (young) 25M->8470K(9216M), 0.0203820 secs] 2014-05-13T13:24:42.686-0700: 10.704: [GC pause (young) 44M->15M(9216M), 0.0288848 secs] 2014-05-13T13:24:48.941-0700: 16.958: [GC pause (young) 51M->20M(9216M), 0.0491244 secs] 2014-05-13T13:24:56.049-0700: 24.066: [GC pause (young) 92M->26M(9216M), 0.0525368 secs] 2014-05-13T13:25:34.368-0700: 62.383: [GC pause (young) 602M->68M(9216M), 0.1721173 secs] But that format wasn't easily read into R, so I needed to be a bit more tricky. I used the following Unix command to create a summary file that was easy for R to read. $ echo "SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime" $ grep "\[GC pause (young" g1gc.log | grep -v mark | sed -e 's/[A-SU-z\(\),]/ /g' -e 's/->/ /' -e 's/: / /g' | more SecondsSinceLaunch BeforeSize AfterSize TotalSize RealTime 2014-05-13T13:24:35.091-0700 3.109 20 5029 9216 0.0146328 2014-05-13T13:24:35.440-0700 3.459 9125 6077 9216 0.0086723 2014-05-13T13:24:37.581-0700 5.599 25 8470 9216 0.0203820 2014-05-13T13:24:42.686-0700 10.704 44 15 9216 0.0288848 2014-05-13T13:24:48.941-0700 16.958 51 20 9216 0.0491244 2014-05-13T13:24:56.049-0700 24.066 92 26 9216 0.0525368 2014-05-13T13:25:34.368-0700 62.383 602 68 9216 0.1721173 Format 2 In some of the log files, the log files with the more verbose format, a single trace, i.e. the report of a singe garbage collection event, was more complicated than Format 1. Here is a text file with an example of a single G1GC trace in the second format. As you can see, it is quite complicated. It is nice that there is so much information available, but the level of detail can be overwhelming. I wrote this awk script (download) to summarize each trace on a single line. #!/usr/bin/env awk -f BEGIN { printf("SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize\n") } ###################### # Save count data from lines that are at the start of each G1GC trace. # Each trace starts out like this: # {Heap before GC invocations=14 (full 0): # garbage-first heap total 9437184K, used 325496K [0xfffffffd00000000, 0xffffffff40000000, 0xffffffff40000000) ###################### /{Heap.*full/{ gsub ( "\\)" , "" ); nf=split($0,a,"="); split(a[2],b," "); getline; if ( match($0, "first") ) { G1GC=1; IncrementalCount=b[1]; FullCount=substr( b[3], 1, length(b[3])-1 ); } else { G1GC=0; } } ###################### # Pull out time stamps that are in lines with this format: # 2014-05-12T14:02:06.025-0700: 94.312: [GC pause (young), 0.08870154 secs] ###################### /GC pause/ { DateTime=$1; SecondsSinceLaunch=substr($2, 1, length($2)-1); } ###################### # Heap sizes are in lines that look like this: # [ 4842M->4838M(9216M)] ###################### /\[ .*]$/ { gsub ( "\\[" , "" ); gsub ( "\ \]" , "" ); gsub ( "->" , " " ); gsub ( "\\( " , " " ); gsub ( "\ \)" , " " ); split($0,a," "); if ( split(a[1],b,"M") > 1 ) {BeforeSize=b[1]*1024;} if ( split(a[1],b,"K") > 1 ) {BeforeSize=b[1];} if ( split(a[2],b,"M") > 1 ) {AfterSize=b[1]*1024;} if ( split(a[2],b,"K") > 1 ) {AfterSize=b[1];} if ( split(a[3],b,"M") > 1 ) {TotalSize=b[1]*1024;} if ( split(a[3],b,"K") > 1 ) {TotalSize=b[1];} } ###################### # Emit an output line when you find input that looks like this: # [Times: user=1.41 sys=0.08, real=0.24 secs] ###################### /\[Times/ { if (G1GC==1) { gsub ( "," , "" ); split($2,a,"="); UserTime=a[2]; split($3,a,"="); SysTime=a[2]; split($4,a,"="); RealTime=a[2]; print DateTime,SecondsSinceLaunch,IncrementalCount,FullCount,UserTime,SysTime,RealTime,BeforeSize,AfterSize,TotalSize; G1GC=0; } } The resulting summary is about 25X smaller that the original file, but still difficult for a human to digest. SecondsSinceLaunch IncrementalCount FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ... 2014-05-12T18:36:34.669-0700: 3985.744 561 0 0.57 0.06 0.16 1724416 1720320 9437184 2014-05-12T18:36:34.839-0700: 3985.914 562 0 0.51 0.06 0.19 1724416 1720320 9437184 2014-05-12T18:36:35.069-0700: 3986.144 563 0 0.60 0.04 0.27 1724416 1721344 9437184 2014-05-12T18:36:35.354-0700: 3986.429 564 0 0.33 0.04 0.09 1725440 1722368 9437184 2014-05-12T18:36:35.545-0700: 3986.620 565 0 0.58 0.04 0.17 1726464 1722368 9437184 2014-05-12T18:36:35.726-0700: 3986.801 566 0 0.43 0.05 0.12 1726464 1722368 9437184 2014-05-12T18:36:35.856-0700: 3986.930 567 0 0.30 0.04 0.07 1726464 1723392 9437184 2014-05-12T18:36:35.947-0700: 3987.023 568 0 0.61 0.04 0.26 1727488 1723392 9437184 2014-05-12T18:36:36.228-0700: 3987.302 569 0 0.46 0.04 0.16 1731584 1724416 9437184 Reading the Data into R Once the GC log data had been cleansed, either by processing the first format with the shell script, or by processing the second format with the awk script, it was easy to read the data into R. g1gc.df = read.csv("summary.txt", row.names = NULL, stringsAsFactors=FALSE,sep="") str(g1gc.df) ## 'data.frame': 8307 obs. of 10 variables: ## $ row.names : chr "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ... ## $ SecondsSinceLaunch: num 1.16 1.47 1.97 3.83 6.1 ... ## $ IncrementalCount : int 0 1 2 3 4 5 6 7 8 9 ... ## $ FullCount : int 0 0 0 0 0 0 0 0 0 0 ... ## $ UserTime : num 0.11 0.05 0.04 0.21 0.08 0.26 0.31 0.33 0.34 0.56 ... ## $ SysTime : num 0.04 0.01 0.01 0.05 0.01 0.06 0.07 0.06 0.07 0.09 ... ## $ RealTime : num 0.02 0.02 0.01 0.04 0.02 0.04 0.05 0.04 0.04 0.06 ... ## $ BeforeSize : int 8192 5496 5768 22528 24576 43008 34816 53248 55296 93184 ... ## $ AfterSize : int 1400 1672 2557 4907 7072 14336 16384 18432 19456 21504 ... ## $ TotalSize : int 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 9437184 ... head(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount ## 1 2014-05-12T14:00:32.868-0700: 1.161 0 ## 2 2014-05-12T14:00:33.179-0700: 1.472 1 ## 3 2014-05-12T14:00:33.677-0700: 1.969 2 ## 4 2014-05-12T14:00:35.538-0700: 3.830 3 ## 5 2014-05-12T14:00:37.811-0700: 6.103 4 ## 6 2014-05-12T14:00:41.428-0700: 9.720 5 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 1 0 0.11 0.04 0.02 8192 1400 9437184 ## 2 0 0.05 0.01 0.02 5496 1672 9437184 ## 3 0 0.04 0.01 0.01 5768 2557 9437184 ## 4 0 0.21 0.05 0.04 22528 4907 9437184 ## 5 0 0.08 0.01 0.02 24576 7072 9437184 ## 6 0 0.26 0.06 0.04 43008 14336 9437184 Basic Statistics Once the data has been read into R, simple statistics are very easy to generate. All of the numbers from high school statistics are available via simple commands. For example, generate a summary of every column: summary(g1gc.df) ## row.names SecondsSinceLaunch IncrementalCount FullCount ## Length:8307 Min. : 1 Min. : 0 Min. : 0.0 ## Class :character 1st Qu.: 9977 1st Qu.:2048 1st Qu.: 0.0 ## Mode :character Median :12855 Median :4136 Median : 12.0 ## Mean :12527 Mean :4156 Mean : 31.6 ## 3rd Qu.:15758 3rd Qu.:6262 3rd Qu.: 61.0 ## Max. :55484 Max. :8391 Max. :113.0 ## UserTime SysTime RealTime BeforeSize ## Min. :0.040 Min. :0.0000 Min. : 0.0 Min. : 5476 ## 1st Qu.:0.470 1st Qu.:0.0300 1st Qu.: 0.1 1st Qu.:5137920 ## Median :0.620 Median :0.0300 Median : 0.1 Median :6574080 ## Mean :0.751 Mean :0.0355 Mean : 0.3 Mean :5841855 ## 3rd Qu.:0.920 3rd Qu.:0.0400 3rd Qu.: 0.2 3rd Qu.:7084032 ## Max. :3.370 Max. :1.5600 Max. :488.1 Max. :8696832 ## AfterSize TotalSize ## Min. : 1380 Min. :9437184 ## 1st Qu.:5002752 1st Qu.:9437184 ## Median :6559744 Median :9437184 ## Mean :5785454 Mean :9437184 ## 3rd Qu.:7054336 3rd Qu.:9437184 ## Max. :8482816 Max. :9437184 Q: What is the total amount of User CPU time spent in garbage collection? sum(g1gc.df$UserTime) ## [1] 6236 As you can see, less than two hours of CPU time was spent in garbage collection. Is that too much? To find the percentage of time spent in garbage collection, divide the number above by total_elapsed_time*CPU_count. In this case, there are a lot of CPU’s and it turns out the the overall amount of CPU time spent in garbage collection isn’t a problem when viewed in isolation. When calculating rates, i.e. events per unit time, you need to ask yourself if the rate is homogenous across the time period in the log file. Does the log file include spikes of high activity that should be separately analyzed? Averaging in data from nights and weekends with data from business hours may alias problems. If you have a reason to suspect that the garbage collection rates include peaks and valleys that need independent analysis, see the “Time Series” section, below. Q: How much garbage is collected on each pass? The amount of heap space that is recovered per GC pass is surprisingly low: At least one collection didn’t recover any data. (“Min.=0”) 25% of the passes recovered 3MB or less. (“1st Qu.=3072”) Half of the GC passes recovered 4MB or less. (“Median=4096”) The average amount recovered was 56MB. (“Mean=56390”) 75% of the passes recovered 36MB or less. (“3rd Qu.=36860”) At least one pass recovered 2GB. (“Max.=2121000”) g1gc.df$Delta = g1gc.df$BeforeSize - g1gc.df$AfterSize summary(g1gc.df$Delta) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0 3070 4100 56400 36900 2120000 Q: What is the maximum User CPU time for a single collection? The worst garbage collection (“Max.”) is many standard deviations away from the mean. The data appears to be right skewed. summary(g1gc.df$UserTime) ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 0.040 0.470 0.620 0.751 0.920 3.370 sd(g1gc.df$UserTime) ## [1] 0.3966 Basic Graphics Once the data is in R, it is trivial to plot the data with formats including dot plots, line charts, bar charts (simple, stacked, grouped), pie charts, boxplots, scatter plots histograms, and kernel density plots. Histogram of User CPU Time per Collection I don't think that this graph requires any explanation. hist(g1gc.df$UserTime, main="User CPU Time per Collection", xlab="Seconds", ylab="Frequency") Box plot to identify outliers When the initial data is viewed with a box plot, you can see the one crazy outlier in the real time per GC. Save this data point for future analysis and drop the outlier so that it’s not throwing off our statistics. Now the box plot shows many outliers, which will be examined later, using times series analysis. Notice that the scale of the x-axis changes drastically once the crazy outlier is removed. par(mfrow=c(2,1)) boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(dominated by a crazy outlier)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") crazy.outlier.df=g1gc.df[g1gc.df$RealTime > 400,] g1gc.df=g1gc.df[g1gc.df$RealTime < 400,] boxplot(g1gc.df$UserTime,g1gc.df$SysTime,g1gc.df$RealTime, main="Box Plot of Time per GC\n(crazy outlier excluded)", names=c("usr","sys","elapsed"), xlab="Seconds per GC", ylab="Time (Seconds)", horizontal = TRUE, outcol="red") box(which = "outer", lty = "solid") Here is the crazy outlier for future analysis: crazy.outlier.df ## row.names SecondsSinceLaunch IncrementalCount ## 8233 2014-05-12T23:15:43.903-0700: 20741 8316 ## FullCount UserTime SysTime RealTime BeforeSize AfterSize TotalSize ## 8233 112 0.55 0.42 488.1 8381440 8235008 9437184 ## Delta ## 8233 146432 R Time Series Data To analyze the garbage collection as a time series, I’ll use Z’s Ordered Observations (zoo). “zoo is the creator for an S3 class of indexed totally ordered observations which includes irregular time series.” require(zoo) ## Loading required package: zoo ## ## Attaching package: 'zoo' ## ## The following objects are masked from 'package:base': ## ## as.Date, as.Date.numeric head(g1gc.df[,1]) ## [1] "2014-05-12T14:00:32.868-0700:" "2014-05-12T14:00:33.179-0700:" ## [3] "2014-05-12T14:00:33.677-0700:" "2014-05-12T14:00:35.538-0700:" ## [5] "2014-05-12T14:00:37.811-0700:" "2014-05-12T14:00:41.428-0700:" options("digits.secs"=3) times=as.POSIXct( g1gc.df[,1], format="%Y-%m-%dT%H:%M:%OS%z:") g1gc.z = zoo(g1gc.df[,-c(1)], order.by=times) head(g1gc.z) ## SecondsSinceLaunch IncrementalCount FullCount ## 2014-05-12 17:00:32.868 1.161 0 0 ## 2014-05-12 17:00:33.178 1.472 1 0 ## 2014-05-12 17:00:33.677 1.969 2 0 ## 2014-05-12 17:00:35.538 3.830 3 0 ## 2014-05-12 17:00:37.811 6.103 4 0 ## 2014-05-12 17:00:41.427 9.720 5 0 ## UserTime SysTime RealTime BeforeSize AfterSize ## 2014-05-12 17:00:32.868 0.11 0.04 0.02 8192 1400 ## 2014-05-12 17:00:33.178 0.05 0.01 0.02 5496 1672 ## 2014-05-12 17:00:33.677 0.04 0.01 0.01 5768 2557 ## 2014-05-12 17:00:35.538 0.21 0.05 0.04 22528 4907 ## 2014-05-12 17:00:37.811 0.08 0.01 0.02 24576 7072 ## 2014-05-12 17:00:41.427 0.26 0.06 0.04 43008 14336 ## TotalSize Delta ## 2014-05-12 17:00:32.868 9437184 6792 ## 2014-05-12 17:00:33.178 9437184 3824 ## 2014-05-12 17:00:33.677 9437184 3211 ## 2014-05-12 17:00:35.538 9437184 17621 ## 2014-05-12 17:00:37.811 9437184 17504 ## 2014-05-12 17:00:41.427 9437184 28672 Example of Two Benchmark Runs in One Log File The data in the following graph is from a different log file, not the one of primary interest to this article. I’m including this image because it is an example of idle periods followed by busy periods. It would be uninteresting to average the rate of garbage collection over the entire log file period. More interesting would be the rate of garbage collect in the two busy periods. Are they the same or different? Your production data may be similar, for example, bursts when employees return from lunch and idle times on weekend evenings, etc. Once the data is in an R Time Series, you can analyze isolated time windows. Clipping the Time Series data Flashing back to our test case… Viewing the data as a time series is interesting. You can see that the work intensive time period is between 9:00 PM and 3:00 AM. Lets clip the data to the interesting period:     par(mfrow=c(2,1)) plot(g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Complete Log File", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") clipped.g1gc.z=window(g1gc.z, start=as.POSIXct("2014-05-12 21:00:00"), end=as.POSIXct("2014-05-13 03:00:00")) plot(clipped.g1gc.z$UserTime, type="h", main="User Time per GC\nTime: Limited to Benchmark Execution", xlab="Time of Day", ylab="CPU Seconds per GC", col="#1b9e77") box(which = "outer", lty = "solid") Cumulative Incremental and Full GC count Here is the cumulative incremental and full GC count. When the line is very steep, it indicates that the GCs are repeating very quickly. Notice that the scale on the Y axis is different for full vs. incremental. plot(clipped.g1gc.z[,c(2:3)], main="Cumulative Incremental and Full GC count", xlab="Time of Day", col="#1b9e77") GC Analysis of Benchmark Execution using Time Series data In the following series of 3 graphs: The “After Size” show the amount of heap space in use after each garbage collection. Many Java objects are still referenced, i.e. alive, during each garbage collection. This may indicate that the application has a memory leak, or may indicate that the application has a very large memory footprint. Typically, an application's memory footprint plateau's in the early stage of execution. One would expect this graph to have a flat top. The steep decline in the heap space may indicate that the application crashed after 2:00. The second graph shows that the outliers in real execution time, discussed above, occur near 2:00. when the Java heap seems to be quite full. The third graph shows that Full GCs are infrequent during the first few hours of execution. The rate of Full GC's, (the slope of the cummulative Full GC line), changes near midnight.   plot(clipped.g1gc.z[,c("AfterSize","RealTime","FullCount")], xlab="Time of Day", col=c("#1b9e77","red","#1b9e77")) GC Analysis of heap recovered Each GC trace includes the amount of heap space in use before and after the individual GC event. During garbage coolection, unreferenced objects are identified, the space holding the unreferenced objects is freed, and thus, the difference in before and after usage indicates how much space has been freed. The following box plot and bar chart both demonstrate the same point - the amount of heap space freed per garbage colloection is surprisingly low. par(mfrow=c(2,1)) boxplot(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", horizontal = TRUE, col="red") hist(as.vector(clipped.g1gc.z$Delta), main="Amount of Heap Recovered per GC Pass", xlab="Size in KB", breaks=100, col="red") box(which = "outer", lty = "solid") This graph is the most interesting. The dark blue area shows how much heap is occupied by referenced Java objects. This represents memory that holds live data. The red fringe at the top shows how much data was recovered after each garbage collection. barplot(clipped.g1gc.z[,c("AfterSize","Delta")], col=c("#7570b3","#e7298a"), xlab="Time of Day", border=NA) legend("topleft", c("Live Objects","Heap Recovered on GC"), fill=c("#7570b3","#e7298a")) box(which = "outer", lty = "solid") When I discuss the data in the log files with the customer, I will ask for an explaination for the large amount of referenced data resident in the Java heap. There are two are posibilities: There is a memory leak and the amount of space required to hold referenced objects will continue to grow, limited only by the maximum heap size. After the maximum heap size is reached, the JVM will throw an “Out of Memory” exception every time that the application tries to allocate a new object. If this is the case, the aplication needs to be debugged to identify why old objects are referenced when they are no longer needed. The application has a legitimate requirement to keep a large amount of data in memory. The customer may want to further increase the maximum heap size. Another possible solution would be to partition the application across multiple cluster nodes, where each node has responsibility for managing a unique subset of the data. Conclusion In conclusion, R is a very powerful tool for the analysis of Java garbage collection log files. The primary difficulty is data cleansing so that information can be read into an R data frame. Once the data has been read into R, a rich set of tools may be used for thorough evaluation.

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• Triangle Line-Segment Intersection - detecting near misses

  - by Will

  A ray is a very poor approximation of a player! I think approximating a player with a sphere traveling a straight line each game tick will solve my problems of the player intersecting edges of scenery because their line segment missed it yet their own model is not infinitely thin... I have a 3D triangle and a line segment. I have the normal triangle-line-segment intersection code which I admit I have only a woolly grasp of. To model movement and compute collisions of the player I have to determine if a line passes within sphere-radius of a triangle. But I can find no convenient line near-miss intersection code! Here's the classic triangle intersection ### commented ### code with my starting assumptions: function triangle_ray_intersection(a,b,c,ray_origin,ray_dir,ray_radius) { // http://softsurfer.com/Archive/algorithm_0105/algorithm_0105.htm#intersect_RayTriangle%28%29 // get triangle edge vectors and plane normal var u = vec3_sub(b,a); var v = vec3_sub(c,a); var n = vec3_cross(u,v); if(n[0]==0 && n[1]==0 && n[2]==0) return null; // triangle is degenerate var w0 = vec3_sub(ray_origin,a); var j = vec3_dot(n,ray_dir); if(Math.abs(j) < 0.00000001) { //### if parallel, might still pass within ray_radius of it return null; // parallel, disjoint or on plane } var i = -vec3_dot(n,w0); // get intersect point of ray with triangle plane var k = i / j; if(k < 0.0) return null; // ray goes away from triangle //### as its a line segment, k > 1+ray_radius means no intersect var hit = vec3_add(ray_origin,vec3_scale(ray_dir,k)); // intersect point of ray and plane // is I inside T? //### here I'm a bit lost; this is presumably computing barycentric coordinates? var uu = vec3_dot(u,u); var uv = vec3_dot(u,v); var vv = vec3_dot(v,v); var w = vec3_sub(hit,a); var wu = vec3_dot(w,u); var wv = vec3_dot(w,v); var D = uv * uv - uu * vv; var s = (uv * wv - vv * wu) / D; //### therefore, compute if its within ray_radius scaled to the 0..1 of barycentric coordinates? if(s<0.0 || s>1.0) return null; // I is outside T var t = (uv * wu - uu * wv) / D; if(t<0.0 || (s+t)>1.0) return null; // I is outside T //### finally, if it passses a barycentric test it might still be too far //### to a point; must check that its distance from a corner is within ray_radius too if more than one barycentric coord is >1 //### so we have rounded corners... return [hit,n]; // I is in T } Given the distance between the point of plane intersection and each corner, I ought to be able to determine distance at world scale of how far beyond the edge - beyond 1.0 in barycentric coordinates for each axis - that point is... At this point my head explodes! Is this the right track? What's the actual code? UPDATE: you can earn 100 pts on SO if you answer this question there...! How can you determine if a line segment passes within some distance of a triangle?

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• In GLSL is it possible to offset vertices based on height map colour?

  - by Rob

  I am attempting to generate some terrain based upon a heightmap. I have generated a 32 x 32 grid and a corresponding height map - In my vertex shader I am trying to offset the position of the Y axis based upon the colour of the heightmap, white vertices being higher than black ones. //Vertex Shader Code #version 330 uniform mat4 modelMatrix; uniform mat4 viewMatrix; uniform mat4 projectionMatrix; uniform sampler2D heightmap; layout (location=0) in vec4 vertexPos; layout (location=1) in vec4 vertexColour; layout (location=3) in vec2 vertexTextureCoord; layout (location=4) in float offset; out vec4 fragCol; out vec4 fragPos; out vec2 fragTex; void main() { // Retreive the current pixel's colour vec4 hmColour = texture(heightmap,vertexTextureCoord); // Offset the y position by the value of current texel's colour value ? vec4 offset = vec4(vertexPos.x , vertexPos.y + hmColour.r, vertexPos.z , 1.0); // Final Position gl_Position = projectionMatrix * viewMatrix * modelMatrix * offset; // Data sent to Fragment Shader. fragCol = vertexColour; fragPos = vertexPos; fragTex = vertexTextureCoord; } However the code I have produced only creates a grid with none of the y vertices higher than any others. This is the C++ code that generates the grid and texture co-orientates which I believe to be correct as the texture is mapped to the grid, hence the white blob in the middle. The grid-lines are generated in the fragment shader, sorry for any confusion. I have tried multiplying the r value of hmColour by 1000 unfortunately that had no effect. The only other problem it could be is that the texture coordinate data is incorrect ? for (int z = 0; z < MAP_Z ; z++) { for(int x = 0; x < MAP_X ; x++) { //Generate Vertex Buffer vertexData[iVertex++] = float (x) * MAP_X; vertexData[iVertex++] = 0; vertexData[iVertex++] = -(float) (z) * MAP_Z; //Colour Buffer NOT NEEDED colourData[iColour++] = 255.0f; // R colourData[iColour++] = 1.0f; // G colourData[iColour++] = 0.0f; // B //Texture Buffer textureData[iTexture++] = (float ) x * (1.0f / MAP_X); textureData[iTexture++] = (float ) z * (1.0f / MAP_Z); } } The heightmap texture I am trying to use appears like so (without grid-lines). This is the corresponding fragment shader // Fragment Shader Code #version 330 uniform sampler2D hmTexture; layout (location=0) out vec4 fragColour; in vec2 fragTex; in vec4 pos; void main(void) { vec2 line = fragTex * 32; // Without Gridlines fragColour = texture(hmTexture,fragTex); // With grid lines // + mix(vec4(0.0, 0.0, 1.0, 0.0), vec4(1.0, 1.0, 1.0, 1.0), // smoothstep(0.05,fract(line.y), 0.99) * smoothstep(0.05,fract(line.x),0.99)); }

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• OpenGL/GLSL: Render to cube map?

  - by BobDole

  I'm trying to figure out how to render my scene to a cube map. I've been stuck on this for a bit and figured I would ask you guys for some help. I'm new to OpenGL and this is the first time I'm using a FBO. I currently have a working example of using a cubemap bmp file, and the samplerCube sample type in the fragment shader is attached to GL_TEXTURE1. I'm not changing the shader code at all. I'm just changing the fact that I wont be calling the function that was loading the cubemap bmp file and trying to use the below code to render to a cubemap. You can see below that I'm also attaching the texture again to GL_TEXTURE1. This is so when I set the uniform: glUniform1i(getUniLoc(myProg, "Cubemap"), 1); it can access it in my fragment shader via uniform samplerCube Cubemap. I'm calling the below function like so: cubeMapTexture = renderToCubeMap(150, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE); Now, I realize in the draw loop below that I'm not changing the view direction to look down the +x, -x, +y, -y, +z, -z axis. I really was just wanting to see something working first before implemented that. I figured I should at least see something on my object the way the code is now. I'm not seeing anything, just straight black. I've made my background white still the object is black. I've removed lighting, and coloring to just sample the cubemap texture and still black. I'm thinking the problem might be the format types when setting my texture which is GL_RGB8, GL_RGBA but I've also tried: GL_RGBA, GL_RGBA GL_RGB, GL_RGB I thought this would be standard since we are rendering to a texture attached to a framebuffer, but I've seen different examples that use different enum values. I've also tried binding the cube map texture in every draw call that I'm wanting to use the cube map: glBindTexture(GL_TEXTURE_CUBE_MAP, cubeMapTexture); Also, I'm not creating a depth buffer for the FBO which I saw in most examples, because I'm only wanting the color buffer for my cube map. I actually added one to see if that was the problem and still got the same results. I could of fudged that up when I tried. Any help that can point me in the right direction would be appreciated. GLuint renderToCubeMap(int size, GLenum InternalFormat, GLenum Format, GLenum Type) { // color cube map GLuint textureObject; int face; GLenum status; //glEnable(GL_TEXTURE_2D); glActiveTexture(GL_TEXTURE1); glGenTextures(1, &textureObject); glBindTexture(GL_TEXTURE_CUBE_MAP, textureObject); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); for (face = 0; face < 6; face++) { glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, InternalFormat, size, size, 0, Format, Type, NULL); } // framebuffer object glGenFramebuffers(1, &fbo); glBindFramebuffer(GL_FRAMEBUFFER, fbo); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X, textureObject, 0); status = glCheckFramebufferStatus(GL_FRAMEBUFFER); printf("%d\"\n", status); printf("%d\n", GL_FRAMEBUFFER_COMPLETE); glViewport(0,0,size, size); for (face = 1; face < 6; face++) { drawSpheres(); glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,GL_TEXTURE_CUBE_MAP_POSITIVE_X + face, textureObject, 0); } //Bind 0, which means render to back buffer, as a result, fb is unbound glBindFramebuffer(GL_FRAMEBUFFER, 0); return textureObject; }

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