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  • Rotating wheel with touch adding velocity

    - by Lewis
    I have a wheel control in a game which is setup like so: - (void)ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [touches anyObject]; CGPoint location = [touch locationInView:[touch view]]; location = [[CCDirector sharedDirector] convertToGL:location]; if (CGRectContainsPoint(wheel.boundingBox, location)) { CGPoint firstLocation = [touch previousLocationInView:[touch view]]; CGPoint location = [touch locationInView:[touch view]]; CGPoint touchingPoint = [[CCDirector sharedDirector] convertToGL:location]; CGPoint firstTouchingPoint = [[CCDirector sharedDirector] convertToGL:firstLocation]; CGPoint firstVector = ccpSub(firstTouchingPoint, wheel.position); CGFloat firstRotateAngle = -ccpToAngle(firstVector); CGFloat previousTouch = CC_RADIANS_TO_DEGREES(firstRotateAngle); CGPoint vector = ccpSub(touchingPoint, wheel.position); CGFloat rotateAngle = -ccpToAngle(vector); CGFloat currentTouch = CC_RADIANS_TO_DEGREES(rotateAngle); wheelRotation += (currentTouch - previousTouch) * 0.6; //limit speed 0.6 } } I update the rotation of a the wheel in the update method by doing: wheel.rotation = wheelRotation; Now once the user lets go of the wheel I want it to rotate back to where it was before but not without taking into account the velocity of the swipe the user has done. This is the bit I really can't get my head around. So if the swipe generates a lot of velocity then the wheel will carry on moving slightly in that direction until the overall force which pulls the wheel back to the starting position kicks in. Any ideas/code snippets?

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  • Would someone please explain Octree Collisions to me?

    - by A-Type
    I've been reading everything I can find on the subject and I feel like the pieces are just about to fall into place, but I just can't quite get it. I'm making a space game, where collisions will occur between planets, ships, asteroids, and the sun. Each of these objects can be subdivided into 'chunks', which I have implemented to speed up rendering (the vertices can and will change often at runtime, so I've separated the buffers). These subdivisions also have bounding primitives to test for collision. All of these objects are made of blocks (yeah, it's that kind of game). Blocks can also be tested for rough collisions, though they do not have individual bounding primitives for memory reasons. I think the rough testing seems to be sufficient, though. So, collision needs to be fairly precise; at block resolution. Some functions rely on two blocks colliding. And, of course, attacking specific blocks is important. Now what I am struggling with is filtering my collision pairs. As I said, I've read a lot about Octrees, but I'm having trouble applying it to my situation as many tutorials are vague with very little code. My main issues are: Are Octrees recalculated each frame, or are they stored in memory and objects are shuffled into different divisions as they move? Despite all my reading I still am not clear on this... the vagueness of it all has been frustrating. How far do Octrees subdivide? Planets in my game are quite large, while asteroids are smaller. Do I subdivide to the size of the planet, or asteroid (where planet is in multiple divisions)? Or is the limit something else entirely, like number of elements in the division? Should I load objects into the octrees as 'chunks' or in the whole, then break into chunks later? This could be specific to my implementation, I suppose. I was going to ask about how big my root needed to be, but I did manage to find this question, and the second answer seems sufficient for me. I'm afraid I don't really get what he means by adding new nodes and doing subdivisions upon adding new objects, probably because I'm confused about whether the tree is maintained in memory or recalculated per-frame.

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  • Where to start learning OpenGL with C++?

    - by NERDcustard
    I'm 16 years old and my name is Norbert. I have learnt C++ and made some cool text based games and such but I would love to start graphic's programming. I'm a decent artiest (I will have some of my work bellow) I know the base of C++ but I really would like to get into OpenGL. I need someone to show me some good tutorials for OpenGl with C++ so I can really get into game dev. My goal is to be able to program a simple 2d game by the end of the year and I have lots of time to do so. I'm en-rolled in a game dev next year and really need some help with starting off. http://imgur.com/QZjKX http://imgur.com/3CZy7

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  • XNA Shader Texture Memory

    - by Alex
    I was wondering about texture optimization in XNA 4.0. Will the the contentmanager send the texturedata to the GPU directly when the texture gets loaded or do I send the texture data to the GPU when I declare a texture in my shader. If that's the case, what happens if I have 5 shaders all using the same texture, does that mean that I send 5 instances of that texture data to the gpu or am I simply telling the GPU what preloaded texture to use? Or does XNA do the heavy lifting in the background?

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  • HLSL How to flip geometry horizontally

    - by cubrman
    I want to flip my asymmetric 3d model horizontally in the vertex shader alongside an arbitrary plane parallel to the YZ plane. This should switch everything for the model from the left hand side to the right hand side (like flipping it in Photoshop). Doing it in pixel shader would be a huge computational cost (extra RT, more fullscreen samples...), so it must be done in the vertex shader. Once more: this is NOT reflection, i need to flip THE WHOLE MODEL. I thought I could simply do the following: Turn off culling. Run the following code in the vertex shader: input.Position = mul(input.Position, World); // World[3][0] holds x value of the model's pivot in the World. if (input.Position.x <= World[3][0]) input.Position.x += World[3][0] - input.Position.x; else input.Position.x -= input.Position.x - World[3][0]; ... The model is never drawn. Where am I wrong? I presume that messes up the index buffer. Can something be done about it? P.S. it's INSANELY HARD to format code here. Thanks to Panda I found my problem. SOLUTION: // Do thins before anything else in the vertex shader. Position.x *= -1; // To invert alongside the object's YZ plane.

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  • What sort of leaderboard for my game?

    - by Martin
    I recently published a word game for Windows Phone and I am really happy to have some players. The game is entirely offline and at the end of a game, the player's score is published to a server. I'm collecting the scores to build a leaderboard. Right now, I don't believe that the leaderboard I offer to my users is appropriate. I essentially accumulate the score of all the games of a user for a given day and that becomes their score. So if Player 1 plays 3 games and gets 100, 150 and 200 points, its score for the day is 450 points. I would like to get your ideas and opinion. How do I keep my game challenging and engaging with a good leaderboard? Should I continue accumulating the score for a day? Should I just keep the best score? Thanks!

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  • Detecting walls or floors in pygame

    - by Serial
    I am trying to make bullets bounce of walls, but I can't figure out how to correctly do the collision detection. What I am currently doing is iterating through all the solid blocks and if the bullet hits the bottom, top or sides, its vector is adjusted accordingly. However, sometimes when I shoot, the bullet doesn't bounce, I think it's when I shoot at a border between two blocks. Here is the update method for my Bullet class: def update(self, dt): if self.can_bounce: #if the bullet hasnt bounced find its vector using the mousclick pos and player pos speed = -10. range = 200 distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]] norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2) direction = [distance[0] / norm, distance[1 ] / norm] bullet_vector = [direction[0] * speed, direction[1] * speed] self.dx = bullet_vector[0] self.dy = bullet_vector[1] #check each block for collision for block in self.game.solid_blocks: last = self.rect.copy() if self.rect.colliderect(block): topcheck = self.rect.top < block.rect.bottom and self.rect.top > block.rect.top bottomcheck = self.rect.bottom > block.rect.top and self.rect.bottom < block.rect.bottom rightcheck = self.rect.right > block.rect.left and self.rect.right < block.rect.right leftcheck = self.rect.left < block.rect.right and self.rect.left > block.rect.left each test tests if it hit the top bottom left or right side of the block its colliding with if self.can_bounce: if topcheck: self.rect = last self.dy *= -1 self.can_bounce = False print "top" if bottomcheck: self.rect = last self.dy *= -1 #Bottom check self.can_bounce = False print "bottom" if rightcheck: self.rect = last self.dx *= -1 #right check self.can_bounce = False print "right" if leftcheck: self.rect = last self.dx *= -1 #left check self.can_bounce = False print "left" else: # if it has already bounced and colliding again kill it self.kill() for enemy in self.game.enemies_list: if self.rect.colliderect(enemy): self.kill() #update position self.rect.x -= self.dx self.rect.y -= self.dy This definitely isn't the best way to do it but I can't think of another way. If anyone has done this or can help that would be awesome!

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  • Saving an interface instance into a Bundle

    - by user22241
    All I've have an interface that allows me to switch between different scenes in my Android game. When the home key is pressed, I am saving all of my states (score, sprite positions etc) into a Bundle. When re-launching, I am restoring all my states and all is OK - however, I can't figure out how to save my 'Scene', thus when I return, it always starts at the default screen which is the 'Main Menu'. How would I go about saving my 'Scene' (into a Bundle)? Code import android.view.MotionEvent; public interface Scene{ void render(); void updateLogic(); boolean onTouchEvent(MotionEvent event); } I assume the interface is the relevant piece of code which is why I've posted that snippet. I set my scene like so: ('options' is an object of my Options class which extends MainMenu (Another custom class) which, in turn implements the interface 'Scene') SceneManager.getInstance().setCurrentScene(options); //Current scene is optionscreen

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  • SDL2 with OpenGL -- weird results, what's wrong?

    - by ber4444
    I'm porting an app to iOS, and therefore need to upgrade it to SDL2 from SDL1.2 (so far I'm testing it as an on OS X desktop app only). However, when running the code with SDL2, I'm getting weird results as shown on the second image below (the first image is how it looks with SDL, correctly). The single changeset that causes this is this one, do you see something obviously wrong there, or does SDL2 have some OpenGL nuances I'm unaware of? My SDL is based on changeset dd7e57847ea9 from HG (since then there is one "Allow specifying of OpenGL 3.2 Core Profile on Mac OS X" commit, not sure if that would help).

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  • Move a 2D square on y axis on android GLES2

    - by Dan
    I am trying to create a simple game for android, to start i am trying to make the square move down the y axis but the way i am doing it dosent move the square at all and i cant find any tutorials for GLES20 The on draw frame function in the render class updates the users position based on accleration dew to gravity, gets the transform matrix from the user class which is used to move the square down, then the program draws it. All that happens is that the square is drawn, no motion happens public void onDrawFrame(GL10 gl) { user.update(0.0, phy.AccelerationDewToGravity); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // Re draws black background GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 12, user.SquareVB);//triangleVB); GLES20.glEnableVertexAttribArray(maPositionHandle); GLES20.glUniformMatrix4fv(maPositionHandle, 1, false, user.getTransformMatrix(), 0); GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4); } The update function in the player class is public void update(double vh, double vv) { Vh += vh; // Increase horrzontal Velosity Vv += vv; // Increase vertical velosity //Matrix.translateM(mMMatrix, 0, (int)Vh, (int)Vv, 0); Matrix.translateM(mMMatrix, 0, mMMatrix, 0, (float)Vh, (float)Vv, 0); }

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  • How do I create a curved line or filled circle or generally a circle using C++/SDL?

    - by NoobScratcher
    Hello I've been trying for ages to make a pixel circle using the putpixel function provided by SDL main website here is that function : void putpixel(int x,int y , int color , SDL_Surface* surface) { unsigned int *ptr = static_cast <unsigned int *> (surface->pixels); int offset = y * (surface->pitch/sizeof(unsigned int)); ptr[offset + x] = color; } and my question is how do I curve a line or create an circle arc of pixels or any other curved shape then a rectangle or singular pixel or line. for example here are some pictures filled pixel circle below enter link description here now my idea was too change the x and y value of the pixel position using + and - to create the curves but in practice didn't provide the correct results what my results are in this is to be able to create a circle that is made out of pixels only nothing else. thank you for anyone who takes the time to read this question thanks! :D

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  • What different ways are there to model restitution in a physics engine?

    - by Mikael Högström
    In my physics engine I give a body a value for restitution between 0 and 1. When two bodies collide there seems to be different views on how the restitution of the collision should be calculated. To me the most intuitive seems to be to take the average of the two but some seem to take only the largest one. Are there other ways to do it? Also, could the closing velocity or some other parameter come into effect?

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  • Water Simulation in LIBGDX [on hold]

    - by Noah Huppert
    I am doing some R&D for a game and am now tackling the topic of water. The goal Make water that can flow. Aka you can have an origin point that water shoots out from or a downhill slope. Make it so water splashes, so when an object hits the water there is a splash. Aka: Actual physics water sim. The current way I know how to do it I know how to create a shader that makes an object look like its water by making waves. Combined with that you can check to see if an object is colliding and apply an upwards force to simulate buoyancy. What is wrong with that way The water does not flow No splashes Possible solutions Have particles that are fairly large that interact with each other to simulate water Possible drawbacks Performance. Question: Is there a better way to do water or is using particles as described the only way?

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  • Make pygame's frame rate faster

    - by Smashery
    By profiling my game, I see that the vast majority of the execution time of my hobby game is between the blit and the flip calls. Currently, it's only running at around 13fps. My video card is fairly decent, so my guess is that pygame is not using it. Does anyone know of any graphics/display options I need to set in pygame to make this faster? Or is this just something that I have to live with since I've chosen pygame?

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  • Cocos2d Tiled Dynamic Object Layer

    - by Rodrigo Camargo
    I'm trying to develop a cocos2d tiled based game using a sort of 'dynamic' object layer. What I want to do is after the tiled map is loaded, the user can drag something into the map and that will become an event when the 'hero' pass over it. I know how to build an object layer in tiled but it seems that is for fixed positions and what I want is a dynamic action position based on what the user can select. For instance, the user can drag a rock into a tile and when the character hit that rock he may die, or something. I'm a little lost about how to make it work. Do you have any idea of what should I use or what should I look for? Thanks in advance!

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  • Find meeting point of 2 objects in 2D, knowing (constant) speed and slope

    - by Axonn
    I have a gun which fires a projectile which has to hit an enemy. The problem is that the gun has to be automatic, i.e. - choose the angle in which it has to shoot so that the projectile hits the enemy dead in the center. It's been a looooong time since school, and my physics skills are a bit rusty, but they're there. I've been thinking to somehow apply the v = d/t formula to find the time needed for the projectile or enemy to reach a certain point. But the problem is that I can't find the common point for both the projectile and enemy. Yes, I can find a certain point for the projectile, and another for the enemy, but I would need lots of tries to find where the point coincides, which is stupid. There has to be a way to link them together but I can't figure it out. I prepared some drawings and samples: A simple version of my Flash game, dumbed down to the basics, just some shapes: http://axonnsd.org/W/P001/MathSandBox.swf - click the mouse anywhere to fire a projectile. Or, here is an image which describes my problem: So... who has any ideas about how to find x3/y3 - thus leading me to find the angle in which the weapon has to tilt in order to fire a projectile to meet the enemy? EDIT I think it would be clearer if I also mention that I know: the speed of both Enemy and Projectile and the Enemy travels on a straight vertical line.

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  • Loading levels from .txt or .XML for XNA

    - by Dave Voyles
    I'm attemptin to add multiple levels to my pong game. I'd like to simply exchange a few elements with each level, nothing crazy. Just the background texture, the color of the AI paddle (the one on the right side), and the music. It seems that the best way to go about this is by utilizing the StreamReader to read and write the files from XML. If there is a better, or more efficient alternative way then I'm all for it. In looking over the XNA Starter Platformer Kit provided by MS it seems that they've done it in this manner as well. I'm perplexed by a few things, however, namely parts within the Level class which aren't commented. /// <summary> /// Iterates over every tile in the structure file and loads its /// appearance and behavior. This method also validates that the /// file is well-formed with a player start point, exit, etc. /// </summary> /// <param name="fileStream"> /// A stream containing the tile data. /// </param> private void LoadTiles(Stream fileStream) { // Load the level and ensure all of the lines are the same length. int width; List<string> lines = new List<string>(); using (StreamReader reader = new StreamReader(fileStream)) { string line = reader.ReadLine(); width = line.Length; while (line != null) { lines.Add(line); if (line.Length != width) throw new Exception(String.Format("The length of line {0} is different from all preceeding lines.", lines.Count)); line = reader.ReadLine(); } } What does width = line.Length mean exactly? I mean I know how it reads the line, but what difference does it make if one line is longer than any of the others? Finally, their levels are simply text files that look like this: .................... .................... .................... .................... .................... .................... .................... .........GGG........ .........###........ .................... ....GGG.......GGG... ....###.......###... .................... .1................X. #################### It can't be that easy..... Can it?

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  • Complete Guide/Tutorials on LWJGL?

    - by user43353
    Dont get me wrong, I finished these tutorials on http://lwjgl.org/wiki/index.php?title=Main_Page. I finished The Basics section, OpenGL 3.2 and newer section, and I looked at the Example Code section. They were great tutorials, and I have looked at the external tutorials as well. I don't know where to go from here, and OpenGL is not my strong point. Some one suggested Learning Modern 3D Graphics Programming, and I didnt learn much. I looked at the port to LWJGL, but the book was on C and I couldn't really understand what the OpenGL meant. I am trying to learn 2D gaming, not 3D. Maybe later. Is there any tutorials that aren't C/C++ heavy and teach you 2D OpenGL?

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  • How do you pack resources in a game when you have too many of them?

    - by ThePlan
    I've recently made a basic space invaders clone in C++ using the Allegro 5 framework. It took me a long time, but after I finished, I realized I had about 10 sprites, and 13MB worth of DLLs (Some of the people didn't even have the mingW dlls) which were making people who played the game very confused. How can I "pack" all my resources in a way that I can easily add-remove data to my game, and to reduce the size taken by the resource, basically placing them in 1 spot? I'm using codeblocks.

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  • How to move a line of sprites in a sine wave?

    - by electroflame
    So, I'm spawning a horizontal line of enemies that I would like to have move in a nice wave. Currently I tried: Enemy.position.X += Enemy.velocity.X; Enemy.position.Y += -(float)Math.Cos(Enemy.position.X / 200) * 5; This...kind of works. But the wave is not a true wave. The top and bottom of one pass are not the same (e.g. 5 for the top, and -5 for the bottom (I don't mean literal points, I just meant that it's not symmetrical)). Is there a better way to do this? I would like the whole line to move in a wave, so it looks fluid. By that, I mean that it should look like each enemy is "following" the one in front of it. The code I posted does have this fluidity to it, but like I said, it's not a perfect wave. Any ideas? Thanks in advance.

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  • 2D basic map system

    - by Cyril
    i'm currently coding a 2D game in Java, and I would like to have some clues on how-to build this system : the screen is moving on a grander map, for instance, the screen represent 800*600 units on a 100K*100K map. When you command your unit to go to another position, the screen move on this map AND when you move your mouse on a side or another of the screen, you move the screen on the map. Not sure that i'm clear, but we can retrieve this system in most RTS games (warcraft/starcraft for example). I'm currently using Slick 2D. Any idea ? Thanks.

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  • Stop a rotating object at a specified angle?

    - by Krummelz
    I'm working in JavaScript with HTML5 and the canvas. I have an object which is rotating at a certain speed, and I need the object's rotation to slow down gradually and the front of the object to stop at a specified angle. (I'm using radians, not degrees.) I have a variable to keep track of the angle which the object is facing, as it rotates. How would I go about getting the object to come to rest, facing the direction I want it to?

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  • Texture displays on Android emulator but not on device

    - by Rob
    I have written a simple UI which takes an image (256x256) and maps it to a rectangle. This works perfectly on the emulator however on the phone the texture does not show, I see only a white rectangle. This is my code: public void onSurfaceCreated(GL10 gl, EGLConfig config) { byteBuffer = ByteBuffer.allocateDirect(shape.length * 4); byteBuffer.order(ByteOrder.nativeOrder()); vertexBuffer = byteBuffer.asFloatBuffer(); vertexBuffer.put(cardshape); vertexBuffer.position(0); byteBuffer = ByteBuffer.allocateDirect(shape.length * 4); byteBuffer.order(ByteOrder.nativeOrder()); textureBuffer = byteBuffer.asFloatBuffer(); textureBuffer.put(textureshape); textureBuffer.position(0); // Set the background color to black ( rgba ). gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Enable Smooth Shading, default not really needed. gl.glShadeModel(GL10.GL_SMOOTH); // Depth buffer setup. gl.glClearDepthf(1.0f); // Enables depth testing. gl.glEnable(GL10.GL_DEPTH_TEST); // The type of depth testing to do. gl.glDepthFunc(GL10.GL_LEQUAL); // Really nice perspective calculations. gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); gl.glEnable(GL10.GL_TEXTURE_2D); loadGLTexture(gl); } public void onDrawFrame(GL10 gl) { gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); gl.glDisable(GL10.GL_DEPTH_TEST); gl.glMatrixMode(GL10.GL_PROJECTION); // Select Projection gl.glPushMatrix(); // Push The Matrix gl.glLoadIdentity(); // Reset The Matrix gl.glOrthof(0f, 480f, 0f, 800f, -1f, 1f); gl.glMatrixMode(GL10.GL_MODELVIEW); // Select Modelview Matrix gl.glPushMatrix(); // Push The Matrix gl.glLoadIdentity(); // Reset The Matrix gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); gl.glLoadIdentity(); gl.glTranslatef(card.x, card.y, 0.0f); gl.glBindTexture(GL10.GL_TEXTURE_2D, texture[0]); //activates texture to be used now gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vertexBuffer); gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer); gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4); gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); } public void onSurfaceChanged(GL10 gl, int width, int height) { // Sets the current view port to the new size. gl.glViewport(0, 0, width, height); // Select the projection matrix gl.glMatrixMode(GL10.GL_PROJECTION); // Reset the projection matrix gl.glLoadIdentity(); // Calculate the aspect ratio of the window GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f, 100.0f); // Select the modelview matrix gl.glMatrixMode(GL10.GL_MODELVIEW); // Reset the modelview matrix gl.glLoadIdentity(); } public int[] texture = new int[1]; public void loadGLTexture(GL10 gl) { // loading texture Bitmap bitmap; bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.image); // generate one texture pointer gl.glGenTextures(0, texture, 0); //adds texture id to texture array // ...and bind it to our array gl.glBindTexture(GL10.GL_TEXTURE_2D, texture[0]); //activates texture to be used now // create nearest filtered texture gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST); gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR); // Use Android GLUtils to specify a two-dimensional texture image from our bitmap GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); // Clean up bitmap.recycle(); } As per many other similar issues and resolutions on the web i have tried setting the minsdkversion is 3, loading the bitmap via an input stream bitmap = BitmapFactory.decodeStream(is), setting BitmapFactory.Options.inScaled to false, putting the images in the nodpi folder and putting them in the raw folder.. all of which didn't help. I'm not really sure what else to try..

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  • Particle System in XNA - cannot draw particle

    - by Dave Voyles
    I'm trying to implement a simple particle system in my XNA project. I'm going by RB Whitaker's tutorial, and it seems simple enough. I'm trying to draw particles within my menu screen. Below I've included the code which I think is applicable. I'm coming up with one error in my build, and it is stating that I need to create a new instance of the EmitterLocation from the particleEngine. When I hover over particleEngine.EmitterLocation = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); it states that particleEngine is returning a null value. What could be causing this? /// <summary> /// Base class for screens that contain a menu of options. The user can /// move up and down to select an entry, or cancel to back out of the screen. /// </summary> abstract class MenuScreen : GameScreen ParticleEngine particleEngine; public void LoadContent(ContentManager content) { if (content == null) { content = new ContentManager(ScreenManager.Game.Services, "Content"); } base.LoadContent(); List<Texture2D> textures = new List<Texture2D>(); textures.Add(content.Load<Texture2D>(@"gfx/circle")); textures.Add(content.Load<Texture2D>(@"gfx/star")); textures.Add(content.Load<Texture2D>(@"gfx/diamond")); particleEngine = new ParticleEngine(textures, new Vector2(400, 240)); } public override void Update(GameTime gameTime, bool otherScreenHasFocus, bool coveredByOtherScreen) { base.Update(gameTime, otherScreenHasFocus, coveredByOtherScreen); // Update each nested MenuEntry object. for (int i = 0; i < menuEntries.Count; i++) { bool isSelected = IsActive && (i == selectedEntry); menuEntries[i].Update(this, isSelected, gameTime); } particleEngine.EmitterLocation = new Vector2(Mouse.GetState().X, Mouse.GetState().Y); particleEngine.Update(); } public override void Draw(GameTime gameTime) { // make sure our entries are in the right place before we draw them UpdateMenuEntryLocations(); GraphicsDevice graphics = ScreenManager.GraphicsDevice; SpriteBatch spriteBatch = ScreenManager.SpriteBatch; SpriteFont font = ScreenManager.Font; spriteBatch.Begin(); // Draw stuff logic spriteBatch.End(); particleEngine.Draw(spriteBatch); }

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  • Viewport / Camera Calculation in 2D Game

    - by Dave
    we have a 2D game with some sprites and tiles and some kind of camera/viewport, that "moves" around the scene. so far so good, if we wouldn't had some special behaviour for your camera/viewport translation. normally you could stick the camera to your player figure and center it, resulting in a very cheap, undergraduate, translation equation, like : vec_translation -/+= speed (depending in what keys are pressed. WASD as default.) buuuuuuuuuut, we want our player figure be able to actually reach the bounds, when the viewport/camera has reached a maximum translation. we came up with the following solution (only keys a and d are the shown here, the rest is just adaption of calculation or maybe YOUR super-cool and elegant solution :) ): if(keys[A]) { playerX -= speed; if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } else if(playerScreenX <= width / 2 && (tx) >= 0) { playerScreenX -= speed; tx = 0; if(playerScreenX < 0) playerScreenX = 0; } else if(playerScreenX >= width / 2 && (tx) < 0) { playerScreenX -= speed; } } if(keys[D]) { playerX += speed; if(playerScreenX >= width / 2 && (-tx + width) < sceneWidth) { playerScreenX = width / 2; tx -= speed; } if(playerScreenX >= width / 2 && (-tx + width) >= sceneWidth) { playerScreenX += speed; tx = -(sceneWidth - width); if(playerScreenX >= width - player.width) playerScreenX = width - player.width; } if(playerScreenX <= width / 2 && (-tx + width) < sceneWidth) { playerScreenX += speed; } } i think the code is rather self explaining: keys is a flag container for currently active keys, playerX/-Y is the position of the player according to world origin, tx/ty are the translation components vital to background / npc / item offset calculation, playerOnScreenX/-Y is the actual position of the player figure (sprite) on screen and width/height are the dimensions of the camera/viewport. this all looks quite nice and works well, but there is a very small and nasty calculation error, which in turn sums up to some visible effect. let's consider following piece of code: if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } it can be translated into plain english as : if the x position of your player figure on screen is less or equal the half of your display / camera / viewport size AND there is enough space left LEFT of your viewport/camera then set players x position on screen to width half, increase translation (because we subtract the translation from something we want to move). easy, right?! doing this will create a small delta between playerX and playerScreenX. after so much talking, my question appears now here at the bottom of this document: how do I stick the calculation of my player-on-screen to the actual position of the player AND having a viewport that is not always centered aroung the players figure? here is a small test-case in processing: http://pastebin.com/bFaTauaa thank you for reading until now and thank you in advance for probably answering my question.

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