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• Inputting cheat codes - hidden keyboard input

  - by Fibericon

  Okay, here's what I want to do - when the player is at the main menu, I want them to be able to type in cheat codes. That's the only place I want it to work. I don't want to give them a text box to type into. Rather, I want them to simply type in a word (let's say "cheat", just for simplicity sake) that activates the cheat code. I only need to capture keyboard input when the window is in focus. What can I do to accomplish this?

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• Should I use float, double, or decimal for stats, position, etc?

  - by Ryan Peschel

  The problem with float and double is that they are not exact. If you are to do something like store replays, the values would have to be exact. The problems with decimal is that they are approximately 16x slower (confirmed by searching and personal testing) than floats and doubles. Couldn't Vector2s be another problem because they use floats internally for all the components? How do other games solve this problem? I'm sure they must use floats and doubles but aren't they not deterministic across platforms and different architecture? The replay files for games like SC2 run in a linear fashion so you cannot skip ahead so how do they solve the determinism issue with floating point numbers?

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• Translate along local axis

  - by Aaron

  I have an object with a position matrix and a rotation matrix (derived from a quaternion, but I digress). I'm able to translate this object along world-relative vectors, but I'm trying to figure out how to translate it along local-relative vectors. So if the object is tilted 45 degrees around its Z-axis the vector (1, 0, 0) would make it move to the upper right. For world-space translations I simply turn the movement vector into a matrix and multiply it by the position matrix: position_mat = translation_mat * position_mat. For local-space translations I'd think I'd have to use the rotation matrix into that formula, but I see the object spin around instead when I apply a translation over time no matter where I multiply the rotation matrix.

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• Normalizing the direction to check if able to move

  - by spartan2417

  i have a a room with 4 walls along the x and z axis respectively. My player who is in first person (therefore the camera) should have collision detection with these walls. I'm relatively new to this so please bare with me. I believe the way to do this is to calculate the direction and distance to the wall from the camera and then normalize the directions. However i can only get this far before i dont know what to do. I think you should work out the angle and direction your facing? where _dx and _dz is the small buffer in front of the camera. float CalcDirection(float Cam_x, float Cam_z, float Wall_x, float Wall_z) { //Calculate direction and distance to obstacle. float ob_dirx = Cam_x + _dx - Wall_x; float ob_dirz = Cam_z + _dz - Wall_z; float ob_dist = sqrt(ob_dirx*ob_dirx + ob_dirz*ob_dirz); //Normalise directions float ob_norm = sqrt(ob_dirx*ob_dirx + ob_dirz*ob_dirz); ob_dirx = (ob_dirx)/ob_norm; ob_dirz = (ob_dirz)/ob_norm; can anyone explain in laymen's terms how i work out the angle?

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• GLSL per pixel lighting with custom light type

  - by Justin

  Ok, I am having a big problem here. I just got into GLSL yesterday, so the code will be terrible, I'm sure. Basically, I am attempting to make a light that can be passed into the fragment shader (for learning purposes). I have four input values: one for the position of the light, one for the color, one for the distance it can travel, and one for the intensity. I want to find the distance between the light and the fragment, then calculate the color from there. The code I have gives me a simply gorgeous ring of light that get's twisted and widened as the matrix is modified. I love the results, but it is not even close to what I am after. I want the light to be moved with all of the vertices, so it is always in the same place in relation to the objects. I can easily take it from there, but getting that to work seems to be impossible with my current structure. Can somebody give me a few pointers (pun not intended)? Vertex shader: attribute vec4 position; attribute vec4 color; attribute vec2 textureCoordinates; varying vec4 colorVarying; varying vec2 texturePosition; varying vec4 fposition; varying vec4 lightPosition; varying float lightDistance; varying float lightIntensity; varying vec4 lightColor; void main() { vec4 ECposition = gl_ModelViewMatrix * gl_Vertex; vec3 tnorm = normalize(vec3 (gl_NormalMatrix * gl_Normal)); fposition = ftransform(); gl_Position = fposition; gl_TexCoord[0] = gl_MultiTexCoord0; fposition = ECposition; lightPosition = vec4(0.0, 0.0, 5.0, 0.0) * gl_ModelViewMatrix * gl_Vertex; lightDistance = 5.0; lightIntensity = 1.0; lightColor = vec4(0.2, 0.2, 0.2, 1.0); } Fragment shader: varying vec4 colorVarying; varying vec2 texturePosition; varying vec4 fposition; varying vec4 lightPosition; varying float lightDistance; varying float lightIntensity; varying vec4 lightColor; uniform sampler2D texture; void main() { float l_distance = sqrt((gl_FragCoord.x * lightPosition.x) + (gl_FragCoord.y * lightPosition.y) + (gl_FragCoord.z * lightPosition.z)); float l_value = lightIntensity / (l_distance / lightDistance); vec4 l_color = vec4(l_value * lightColor.r, l_value * lightColor.g, l_value * lightColor.b, l_value * lightColor.a); vec4 color; color = texture2D(texture, gl_TexCoord[0].st); gl_FragColor = l_color * color; //gl_FragColor = fposition; }

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• LWJGL GL_QUADS texture artifact

  - by Dajgoro Labinac

  I managed to get working lwjgl in Java, and i loaded a test image(tv test card), but i keep getting weird artifacts outside the image. Image link: http://tinypic.com/r/vhv9g/6 Code: glBegin(GL_QUADS); glTexCoord2f(0, 0); glVertex2i(10, 10); glTexCoord2f(1, 0); glVertex2i(500, 10); glTexCoord2f(1, 1); glVertex2i(500, 500); glTexCoord2f(0, 1); glVertex2i(10, 500); glEnd(); What could be the cause?

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• Pseudo-magnet implementation with chipmunk

  - by Eimantas

  How should I go about implementing "natural" magnet on a certain body in chipmunk space? Context is of simple bodies lying in the space (think chessboard). When one of the figures is activated as a magnet - others should start moving towards it. Currently I'm applying force (cpBodyApplyForce)to the other figures with vector calculated towards the activated figure. However this doesn't really feel "natural". Are there any known algorithms for imitating magnets?

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• Recreating Doodle Jump in Canvas - Platforms spawning out of reach

  - by kushsolitary

  I have started to recreate Doodle Jump in HTML using Canvas. Here's my current progress. As you can see, if you play it for a few seconds, some platforms will be out of the player's reach. I don't know why is this happening. Here's the code which is responsible for the re-spawning of platforms. //Movement of player affected by gravity if(player.y > (height / 2) - (player.height / 2)) { player.y += player.vy; player.vy += gravity; } else { for(var i = 0; i < platforms.length; i++) { var p = platforms[i]; if(player.vy < 0) { p.y -= player.vy; player.vy += 0.08; } if(p.y > height) { position = 0; var h = p.y; platforms[i] = new Platform(); } if(player.vy >= 0) { player.y += player.vy; player.vy += gravity; } } } Also, here's the platform class. //Platform class function Platform(y) { this.image = new Image(); this.image.src = platformImg; this.width = 105; this.height = 25; this.x = Math.random() * (width - this.width); this.y = y || position; position += height / platformCount; //Function to draw it this.draw = function() { try { ctx.drawImage(this.image, this.x, this.y, this.width, this.height); } catch(e) {} }; } You can also see the whole code on the link I provided. Also, when a platform goes out of the view port, the jump animation becomes quirky. I am still trying to find out what's causing this but can't find any solution.

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• Problem with sprite direction and rotation

  - by user2236165

  I have a sprite called Tool that moves with a speed represented as a float and in a direction represented as a Vector2. When I click the mouse on the screen the sprite change its direction and starts to move towards the mouseclick. In addition to that I rotate the sprite so that it is facing in the direction it is heading. However, when I add a camera that is suppose to follow the sprite so that the sprite is always centered on the screen, the sprite won't move in the given direction and the rotation isn't accurate anymore. This only happens when I add the Camera.View in the spriteBatch.Begin(). I was hoping anyone could maybe shed a light on what I am missing in my code, that would be highly appreciated. Here is the camera class i use: public class Camera { private const float zoomUpperLimit = 1.5f; private const float zoomLowerLimit = 0.1f; private float _zoom; private Vector2 _pos; private int ViewportWidth, ViewportHeight; #region Properties public float Zoom { get { return _zoom; } set { _zoom = value; if (_zoom < zoomLowerLimit) _zoom = zoomLowerLimit; if (_zoom > zoomUpperLimit) _zoom = zoomUpperLimit; } } public Rectangle Viewport { get { int width = (int)((ViewportWidth / _zoom)); int height = (int)((ViewportHeight / _zoom)); return new Rectangle((int)(_pos.X - width / 2), (int)(_pos.Y - height / 2), width, height); } } public void Move(Vector2 amount) { _pos += amount; } public Vector2 Position { get { return _pos; } set { _pos = value; } } public Matrix View { get { return Matrix.CreateTranslation(new Vector3(-_pos.X, -_pos.Y, 0)) * Matrix.CreateScale(new Vector3(Zoom, Zoom, 1)) * Matrix.CreateTranslation(new Vector3(ViewportWidth * 0.5f, ViewportHeight * 0.5f, 0)); } } #endregion public Camera(Viewport viewport, float initialZoom) { _zoom = initialZoom; _pos = Vector2.Zero; ViewportWidth = viewport.Width; ViewportHeight = viewport.Height; } } And here is my Update and Draw-method: protected override void Update (GameTime gameTime) { float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; TouchCollection touchCollection = TouchPanel.GetState (); foreach (TouchLocation tl in touchCollection) { if (tl.State == TouchLocationState.Pressed || tl.State == TouchLocationState.Moved) { //direction the tool shall move towards direction = touchCollection [0].Position - toolPos; if (direction != Vector2.Zero) { direction.Normalize (); } //change the direction the tool is moving and find the rotationangle the texture must rotate to point in given direction toolPos += (direction * speed * elapsed); RotationAngle = (float)Math.Atan2 (direction.Y, direction.X); } } if (direction != Vector2.Zero) { direction.Normalize (); } //move tool in given direction toolPos += (direction * speed * elapsed); //change cameracentre to the tools position Camera.Position = toolPos; base.Update (gameTime); } protected override void Draw (GameTime gameTime) { graphics.GraphicsDevice.Clear (Color.Blue); spriteBatch.Begin (SpriteSortMode.BackToFront, BlendState.AlphaBlend, null, null, null, null, Camera.View); spriteBatch.Draw (tool, new Vector2 (toolPos.X, toolPos.Y), null, Color.White, RotationAngle, originOfToolTexture, 1, SpriteEffects.None, 1); spriteBatch.End (); base.Draw (gameTime); }

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• Setting uniform value of a vertex shader for different sprites in a SpriteBatch

  - by midasmax

  I'm using libGDX and currently have a simple shader that does a passthrough, except for randomly shifting the vertex positions. This shift is a vec2 uniform that I set within my code's render() loop. It's declared in my vertex shader as uniform vec2 u_random. I have two different kind of Sprites -- let's called them SpriteA and SpriteB. Both are drawn within the same SpriteBatch's begin()/end() calls. Prior to drawing each sprite in my scene, I check the type of the sprite. If sprite instance of SpriteA: I set the uniform u_random value to Vector2.Zero, meaning that I don't want any vertex changes for it. If sprite instance of SpriteB, I set the uniform u_random to Vector2(MathUtils.random(), MathUtils.random(). The expected behavior was that all the SpriteA objects in my scene won't experience any jittering, while all SpriteB objects would be jittering about their positions. However, what I'm experiencing is that both SpriteA and SpriteB are jittering, leading me to believe that the u_random uniform is not actually being set per Sprite, and being applied to all sprites. What is the reason for this? And how can I fix this such that the vertex shader correctly accepts the uniform value set to affect each sprite individually? passthrough.vsh attribute vec4 a_color; attribute vec3 a_position; attribute vec2 a_texCoord0; uniform mat4 u_projTrans; uniform vec2 u_random; varying vec4 v_color; varying vec2 v_texCoord; void main() { v_color = a_color; v_texCoord = a_texCoord0; vec3 temp_position = vec3( a_position.x + u_random.x, a_position.y + u_random.y, a_position.z); gl_Position = u_projTrans * vec4(temp_position, 1.0); } Java Code this.batch.begin(); this.batch.setShader(shader); for (Sprite sprite : sprites) { Vector2 v = Vector2.Zero; if (sprite instanceof SpriteB) { v.x = MathUtils.random(-1, 1); v.y = MathUtils.random(-1, 1); } shader.setUniformf("u_random", v); sprite.draw(this.batch); } this.batch.end();

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• Speed up content loading

  - by user1806687

  I am using WinForms Sample downloaded from microsoft website. The problem is, that the model loading time is quite long, using: contentBuilder.Add(ModelPath, ModelName, null, "ModelProcessor"); contentManager.Load<Model>(ModelName); even a simple model, such as a cube with no textures, takes 4+ seconds to load. Now, I am no expert on this, but is there anyway to decrease loading time? EDIT: I've gone thru the code and found out that calling contentBuilder.Build(); ,which comes right after contentBuilder.Add() method takes up most of the time.

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• Wall avoidance steering

  - by Vodemki

  I making a small steering simulator using the reynolds boid algorythm. Now I want to add a wall avoidance feature. My walls are in 3D and defined using two points like that: ---------. P2 | | P1 .--------- My agents have a velocity, a position, etc... Could you tell me how to make avoidance with my agents ? Vector2D ReynoldsSteeringModel::repulsionFromWalls() { Vector2D force; vector<Wall *> wallsList = walls(); Point2D pos = self()->position(); Vector2D velocity = self()->velocity(); for (unsigned i=0; i<wallsList.size(); i++) { //TODO } return force; } Then I use all the forces returned by my boid functions and I apply it to my agent. I just need to know how to do that with my walls ? Thanks for your help.

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• Information about rendering, batches, the graphical card, performance etc. + XNA?

  - by Aidiakapi

  I know the title is a bit vague but it's hard to describe what I'm really looking for, but here goes. When it comes to CPU rendering, performance is mostly easy to estimate and straightforward, but when it comes to the GPU due to my lack of technical background information, I'm clueless. I'm using XNA so it'd be nice if theory could be related to that. So what I actually wanna know is, what happens when and where (CPU/GPU) when you do specific draw actions? What is a batch? What influence do effects, projections etc have? Is data persisted on the graphics card or is it transferred over every step? When there's talk about bandwidth, are you talking about a graphics card internal bandwidth, or the pipeline from CPU to GPU? Note: I'm not actually looking for information on how the drawing process happens, that's the GPU's business, I'm interested on all the overhead that precedes that. I'd like to understand what's going on when I do action X, to adapt my architectures and practices to that. Any articles (possibly with code examples), information, links, tutorials that give more insight in how to write better games are very much appreciated. Thanks :)

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• specifying an object type at runtime

  - by lapin

  I've written a Vbo template class to work with opengl. I'd like to set the type from a config file at runtime. e.g. <vbo type="bump_vt" ... /> Vbo* pVbo = new Vbo(bump_vt, ...); Is there some way I can do this without a large if else block e.g. if( sType.compareTo("bump_vt") == 0 ) Vbo* pVbo = new Vbo(bump_vt, ...); else if ... I'm writing for multiple platforms in c++. thanks

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• Direct3D - Zooming into Mouse Position

  - by roohan

  I'm trying to implement my camera class for a simulation. But I cant figure out how to zoom into my world based on the mouse position. I mean the object under the mouse cursor should remain at the same screen position. My zooming looks like this: VOID ZoomIn(D3DXMATRIX& WorldMatrix, FLOAT const& MouseX, FLOAT const& MouseY) { this->Position.z = this->Position.z * 0.9f; D3DXMatrixLookAtLH(&this->ViewMatrix, &this->Position, &this->Target, &this->UpDirection); } I passed the world matrix to the function because I had the idea to move my drawing origin according to the mouse position. But I cant find out how to calculate the offset in to move my drawing origin. Anyone got an idea how to calculate this? Thanks in advance. SOLVED Ok I solved my problem. Here is the code if anyone is interested: VOID CAMERA2D::ZoomIn(FLOAT const& MouseX, FLOAT const& MouseY) { // Get the setting of the current view port. D3DVIEWPORT9 ViewPort; this->Direct3DDevice->GetViewport(&ViewPort); // Convert the screen coordinates of the mouse to world space coordinates. D3DXVECTOR3 VectorOne; D3DXVECTOR3 VectorTwo; D3DXVec3Unproject(&VectorOne, &D3DXVECTOR3(MouseX, MouseY, 0.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); D3DXVec3Unproject(&VectorTwo, &D3DXVECTOR3(MouseX, MouseY, 1.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); // Calculate the resulting vector components. float WorldZ = 0.0f; float WorldX = ((WorldZ - VectorOne.z) * (VectorTwo.x - VectorOne.x)) / (VectorTwo.z - VectorOne.z) + VectorOne.x; float WorldY = ((WorldZ - VectorOne.z) * (VectorTwo.y - VectorOne.y)) / (VectorTwo.z - VectorOne.z) + VectorOne.y; // Move the camera into the screen. this->Position.z = this->Position.z * 0.9f; D3DXMatrixLookAtLH(&this->ViewMatrix, &this->Position, &this->Target, &this->UpDirection); // Calculate the world space vector again based on the new view matrix, D3DXVec3Unproject(&VectorOne, &D3DXVECTOR3(MouseX, MouseY, 0.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); D3DXVec3Unproject(&VectorTwo, &D3DXVECTOR3(MouseX, MouseY, 1.0f), &ViewPort, &this->ProjectionMatrix, &this->ViewMatrix, &WorldMatrix); // Calculate the resulting vector components. float WorldZ2 = 0.0f; float WorldX2 = ((WorldZ2 - VectorOne.z) * (VectorTwo.x - VectorOne.x)) / (VectorTwo.z - VectorOne.z) + VectorOne.x; float WorldY2 = ((WorldZ2 - VectorOne.z) * (VectorTwo.y - VectorOne.y)) / (VectorTwo.z - VectorOne.z) + VectorOne.y; // Create a temporary translation matrix for calculating the origin offset. D3DXMATRIX TranslationMatrix; D3DXMatrixIdentity(&TranslationMatrix); // Calculate the origin offset. D3DXMatrixTranslation(&TranslationMatrix, WorldX2 - WorldX, WorldY2 - WorldY, 0.0f); // At the offset to the cameras world matrix. this->WorldMatrix = this->WorldMatrix * TranslationMatrix; } Maybe someone has even a better solution than mine.

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• What is the recommended way to output values to FBO targets? (OpenGL 3.3 + GLSL 330)

  - by datSilencer

  I'll begin by apologizing for any dumb assumptions you might find in the code below since I'm still pretty much green when it comes to OpenGL programming. I'm currently trying to implement deferred shading by using FBO's and their associated targets (textures in my case). I have a simple (I think :P) geometry+fragment shader program and I'd like to write its Fragment Shader stage output to three different render targets (previously bound by a call to glDrawBuffers()), like so: #version 330 in vec3 WorldPos0; in vec2 TexCoord0; in vec3 Normal0; in vec3 Tangent0; layout(location = 0) out vec3 WorldPos; layout(location = 1) out vec3 Diffuse; layout(location = 2) out vec3 Normal; uniform sampler2D gColorMap; uniform sampler2D gNormalMap; vec3 CalcBumpedNormal() { vec3 Normal = normalize(Normal0); vec3 Tangent = normalize(Tangent0); Tangent = normalize(Tangent - dot(Tangent, Normal) * Normal); vec3 Bitangent = cross(Tangent, Normal); vec3 BumpMapNormal = texture(gNormalMap, TexCoord0).xyz; BumpMapNormal = 2 * BumpMapNormal - vec3(1.0, 1.0, -1.0); vec3 NewNormal; mat3 TBN = mat3(Tangent, Bitangent, Normal); NewNormal = TBN * BumpMapNormal; NewNormal = normalize(NewNormal); return NewNormal; } void main() { WorldPos = WorldPos0; Diffuse = texture(gColorMap, TexCoord0).xyz; Normal = CalcBumpedNormal(); } If my render target textures are configured as: RT1:(GL_RGB32F, GL_RGB, GL_FLOAT, GL_TEXTURE0, GL_COLOR_ATTACHMENT0) RT2:(GL_RGB32F, GL_RGB, GL_FLOAT, GL_TEXTURE1, GL_COLOR_ATTACHMENT1) RT3:(GL_RGB32F, GL_RGB, GL_FLOAT, GL_TEXTURE2, GL_COLOR_ATTACHMENT2) And assuming that each texture has an internal format capable of contaning the incoming data, will the fragment shader write the corresponding values to the expected texture targets? On a related note, do the textures need to be bound to the OpenGL context when they are Multiple Render Targets? From some Googling, I think there are two other ways to output to MRTs: 1: Output each component to gl_FragData[n]. Some forum posts say this method is deprecated. However, looking at the latest OpenGL 3.3 and 4.0 specifications at opengl.org, the core profiles still mention this approach. 2: Use a typed output array variable for the expected type. In this case, I think it would be something like this: out vec3 [3] output; void main() { output[0] = WorldPos0; output[1] = texture(gColorMap, TexCoord0).xyz; output[2] = CalcBumpedNormal(); } So which is then the recommended approach? Is there a recommended approach at all if I plan to code on top of OpenGL 3.3? Thanks for your time and help!

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• Do I need the 'w' component in my Vector class?

  - by bobobobo

  Assume you're writing matrix code that handles rotation, translation etc for 3d space. Now the transformation matrices have to be 4x4 to fit the translation component in. However, you don't actually need to store a w component in the vector do you? Even in perspective division, you can simply compute and store w outside of the vector, and perspective divide before returning from the method. For example: // post multiply vec2=matrix*vector Vector operator*( const Matrix & a, const Vector& v ) { Vector r ; // do matrix mult r.x = a._11*v.x + a._12*v.y ... real w = a._41*v.x + a._42*v.y ... // perspective divide r /= w ; return r ; } Is there a point in storing w in the Vector class?

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• XNA- Texturing problem, exporting model

  - by user1806687

  How,can I disable coloring when texture is applied, because right now the texture is being colored over. foreach (BasicEffect effect in mesh.Effects) { effect.TextureEnabled = textureApplied; if(textureApplied) effect.Texture = Texture2D.FromStream(GraphicsDevice,System.IO.File.OpenRead(texturePath)); else { effect.DiffuseColor = ti.DiffuseColor; effect.EmissiveColor = ti.EmissiveColor; } ... } mesh.Draw(); Also, is there any easy way for xna to export models? Or do I have to write my own?

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• Random enemy placement on a 2d grid

  - by Robb

  I want to place my items and enemies randomly (or as randomly as possible). At the moment I use XNA's Random class to generate a number between 800 for X and 600 for Y. It feels like enemies spawn more towards the top of the map than in the middle or bottom. I do not seed the generator, maybe that is something to consider. Are there other techniques described that can improve random enemy placement on a 2d grid?

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• Ad Service That Lets You Choose Your Ad, and Then Some [on hold]

  - by user3634450

  I'm trying to build an app for both Android and/or iOS where part of the gameplay actually involves ads as a texture. I need to be able to choose which ads I would like to use. I need to be able to be able to identify the ads (which if I can choose which ads show up in the app shouldn't be that hard). I need to be able to swap in and out new ads on what could possibly be a daily basis (and don't want to have to update the app to do it). And as if that wasn't too needy a list, I need to be able to load 50 ads from the pool of ads I deem fit, all to each and every user of the app at least every couple of days. I don't care if the ads pay, I'm not looking for clicks, but I don't want to have to make 50 fake ads every couple of days, from an "artistic" level I don't want the content to feel phony or fake, and I don't really have a way to load content to each user via some internet source (if anyone could name one that would be great). I'm not sure what kind of ad provider would like or even approve of this, in fact just what I've described might be against Google Play's or iTunes' content developer policies, but if anyone could give me any advice to steer me in the right direction it would be greatly appreciated, thank you.

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• Point in Polygon, Ray Method: ending infinite line

  - by user2878528

  Having a bit of trouble with point in polygon collision detection using the ray method i.e. http://en.wikipedia.org/wiki/Point_in_polygon My problem is I need to give an end to the infinite line created. As with this infinite line I always get an even number of intersections and hence an invalid result. i.e. ignore or intersection to the right of the point being checked what I have what I want My current code based of Mecki awesome response for (int side = 0; side < vertices.Length; side++) { // Test if current side intersects with ray. // create infinite line // See: http://en.wikipedia.org/wiki/Linear_equation a = end_point.Y - start_point.Y; b = start_point.X - end_point.X; c = end_point.X * start_point.Y - start_point.X * end_point.Y; //insert points of vector d2 = a * vertices[side].Position.X + b * vertices[side].Position.Y + c; if (side - 1 < 0) d1 = a * vertices[vertices.Length - 1].Position.X + b * vertices[vertices.Length - 1].Position.Y + c; else d1 = a * vertices[side-1].Position.X + b * vertices[side-1].Position.Y + c; // If points have opposite sides, intersections++; if (d1 > 0 && d2 < 0 ) intersections++; if (d1 < 0 && d2 > 0 ) intersections++; } //if intersections odd inside = true if ((intersections % 2) == 1) inside = true; else inside = false;

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• In 3D camera math, calculate what Z depth is pixel unity for a given FOV

  - by badweasel

  I am working in iOS and OpenGL ES 2.0. Through trial and error I've figured out a frustum to where at a specific z depth pixels drawn are 1 to 1 with my source textures. So 1 pixel in my texture is 1 pixel on the screen. For 2d games this is good. Of course it means that I also factor in things like the size of the quad and the size of the texture. For example if my sprite is a quad 32x32 pixels. The quad size is 3.2 units wide and tall. And the texcoords are 32 / the size of the texture wide and tall. Then the frustum is: matrixFrustum(-(float)backingWidth/frustumScale,(float)backingWidth/frustumScale, -(float)backingHeight/frustumScale, (float)backingHeight/frustumScale, 40, 1000, mProjection); Where frustumScale is 800 for a retina screen. Then at a distance of 800 from camera the sprite is pixel for pixel the same as photoshop. For 3d games sometimes I still want to be able to do this. But depending on the scene I sometimes need the FOV to be different things. I'm looking for a way to figure out what Z depth will achieve this same pixel unity for a given FOV. For this my mProjection is set using: matrixPerspective(cameraFOV, near, far, (float)backingWidth / (float)backingHeight, mProjection); With testing I found that at an FOV of 45.0 a Z of 38.5 is very close to pixel unity. And at an FOV of 30.0 a Z of 59.5 is about right. But how can I calculate a value that is spot on? Here's my matrixPerspecitve code: void matrixPerspective(float angle, float near, float far, float aspect, mat4 m) { //float size = near * tanf(angle / 360.0 * M_PI); float size = near * tanf(degreesToRadians(angle) / 2.0); float left = -size, right = size, bottom = -size / aspect, top = size / aspect; // Unused values in perspective formula. m[1] = m[2] = m[3] = m[4] = 0; m[6] = m[7] = m[12] = m[13] = m[15] = 0; // Perspective formula. m[0] = 2 * near / (right - left); m[5] = 2 * near / (top - bottom); m[8] = (right + left) / (right - left); m[9] = (top + bottom) / (top - bottom); m[10] = -(far + near) / (far - near); m[11] = -1; m[14] = -(2 * far * near) / (far - near); } And my mView is set using: lookAtMatrix(cameraPos, camLookAt, camUpVector, mView); * UPDATE * I'm going to leave this here in case anyone has a different solution, can explain how they do it, or why this works. This is what I figured out. In my system I use a 10th scale unit to pixels on non-retina displays and a 20th scale on retina displays. The iPhone is 640 pixels wide on retina and 320 pixels wide on non-retina (obsolete). So if I want something to be the full screen width I divide by 20 to get the OpenGL unit width. Then divide that by 2 to get the left and right unit position. Something 32 units wide centered on the screen goes from -16 to +16. Believe it or not I have an excel spreadsheet do all this math for me and output all the vertex data for my sprite sheet. It's an arbitrary thing I made up to do .1 units = 1 non-retina pixel or 2 retina pixels. I could have made it .01 units = 2 pixels and someday I might switch to that. But for now it's the other. So the width of the screen in units is 32.0, and that means the left most pixel is at -16.0 and the right most is at 16.0. After messing a bit I figured out that if I take the [0] value of an identity modelViewProjection matrix and multiply it by 16 I get the depth required to get 1:1 pixels. I don't know why. I don't know if the 16 is related to the screen size or just a lucky guess. But I did a test where I placed a sprite at that calculated depth and varied the FOV through all the valid values and the object stays steady on screen with 1:1 pixels. So now I'm just calculating the unityDepth that way. If someone gives me a better answer I'll checkmark it.

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• libGDX using Stage and Actor produces different camera angles on desktop and Android Phone

  - by Brandon

  libGDX using Stage and Actor produces different camera angles on desktop and Android Phone. Here are pictures demonstrating the problem: http://brandonyuh.minus.com/mFpdTSgN17VUq On the desktop version, the image takes up most all the screen. On the Android phone it only takes up a bit of the screen. Here's the code (not my actual project but I isolated the problem): package com.me.mygdxgame2; import com.badlogic.gdx.*; import com.badlogic.gdx.graphics.*; import com.badlogic.gdx.graphics.Texture.TextureFilter; import com.badlogic.gdx.graphics.g2d.*; import com.badlogic.gdx.scenes.scene2d.*; public class MyGdxGame2 implements ApplicationListener { private Stage stage; public void create() { stage = new Stage(); stage.addActor(new ActorHi()); } public void render() { Gdx.gl.glClearColor(0, 1, 0, 1); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); stage.draw(); } public void dispose() {} public void resize(int width, int height) {} public void pause() {} public void resume() {} public class ActorHi extends Actor { private Sprite sprite; public ActorHi() { Texture texture = new Texture(Gdx.files.internal("data/hi.png")); texture.setFilter(TextureFilter.Linear, TextureFilter.Linear); sprite = new Sprite(new TextureRegion(texture, 0, 0, 128, 128)); sprite.setBounds(0, 0, 300.0f, 300.0f); } public void draw(SpriteBatch batch, float parentAlpha) { sprite.draw(batch); } } } hi.png is included in the above link Thank you very much for answering my question. I've spent 3 days trying to figure it out.

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• Why isnt my data persisting with nskeyedarchiver?

  - by aking63

  Im just working on what should be the "finishing touches" of my first iPhone game. For some reason, when I save with NSKeyedArchiver/Unarchiver, the data seems to load once and then gets lost or something. Here's what I've been able to deduce: When I save in this viewController, pop to the previous one, and then push back into this one, the data is saved and prints as I want it to. But when I save in this viewController, then push a new one and pop back into this one, the data is lost. Any idea why this might be happening? Do I have this set up all wrong? I copied it from a book months ago. Here's the methods I use to save and load. - (void) saveGameData { NSLog(@"LS:saveGameData"); // SAVE DATA IMMEDIATELY NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *gameStatePath = [documentsDirectory stringByAppendingPathComponent:@"gameState.dat"]; NSMutableData *gameSave= [NSMutableData data]; NSKeyedArchiver *encoder = [[NSKeyedArchiver alloc] initForWritingWithMutableData:gameSave]; [encoder encodeObject:categoryLockStateArray forKey:kCategoryLockStateArray]; [encoder encodeObject:self.levelsPlist forKey:@"levelsPlist"]; [encoder finishEncoding]; [gameSave writeToFile:gameStatePath atomically:YES]; NSLog(@"encoded catLockState:%@",categoryLockStateArray); } - (void) loadGameData { NSLog(@"loadGameData"); // If there is a saved file, perform the load NSMutableData *gameData = [NSData dataWithContentsOfFile:[[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:@"gameState.dat"]]; // LOAD GAME DATA if (gameData) { NSLog(@"-Loaded Game Data-"); NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:gameData]; self.levelsPlist = [unarchiver decodeObjectForKey:@"levelsPlist"]; categoryLockStateArray = [unarchiver decodeObjectForKey:kCategoryLockStateArray]; NSLog(@"decoded catLockState:%@",categoryLockStateArray); } // CREATE GAME DATA else { NSLog(@"-Created Game Data-"); self.levelsPlist = [[NSMutableDictionary alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:kLevelsPlist ofType:@"plist"]]; } if (!categoryLockStateArray) { NSLog(@"-Created categoryLockStateArray-"); categoryLockStateArray = [[NSMutableArray alloc] initWithCapacity:[[self.levelsPlist allKeys] count]]; for (int i=0; i<[[self.levelsPlist allKeys] count]; i++) { [categoryLockStateArray insertObject:[NSNumber numberWithBool:FALSE] atIndex:i]; } } // set the properties of the categories self.categoryNames = [self.levelsPlist allKeys]; NUM_CATEGORIES = [self.categoryNames count]; thisCatCopy = [[NSMutableDictionary alloc] initWithDictionary:[[levelsPlist objectForKey:[self.categoryNames objectAtIndex:pageControl.currentPage]] mutableCopy]]; NUM_FINISHED = [[thisCatCopy objectForKey:kNumLevelsBeatenInCategory] intValue]; }

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• infer half vector length in BRDF

  - by cician

  it's my first question on stack. Is it possible to infer length of the half angle vector for specular lighting from N·L and N·V without the whole view and light vectors? I may be completely off-track, but I have this gut feeling it's possible... Why? I'm working on a skin shader and I'm already doing one texture lookup with N·L+N·E and one texture lookup for specular with N·H+N·V. The latter one can be transformed into N·L+N·E lookup if only I had the half vector length. Doing so could simplify the shader a bit and move some operations into the pre-computed lookup texture. It would make a huge difference since I'm trying to squeeze as much functionality as possible to a single pass mobile version so instruction count matters. Thanks.

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