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• Making body (box2d) a sprite (andengine) in Android

  - by Kadir

  I can't make body (box2d) a sprite (andengine) and at the same time apply MoveModifier to sprite which is body. If i can make just body, it works namely the sprites can collide. If I apply just MoveModifier to sprites, the sprites can move where i want. But I want to make body (they can collide) and apply MoveModifier (they can move where I want) at the same time. How can i do it? This my code just run MoveModifier not as body at the same time. circles[i] = new Sprite(startX, startY, textRegCircle[i]); body[i] = PhysicsFactory.createCircleBody(physicsWorld, circles[i], BodyType.DynamicBody, FIXTURE_DEF); physicsWorld.registerPhysicsConnector(new PhysicsConnector(circles[i], body[i], true, true)); circles[i].registerEntityModifier( (IEntityModifier) new SequenceEntityModifier ( new MoveModifier(10.0f, circles[i].getX(), circles[i].getX(), circles[i].getY(),CAMERA_HEIGHT+64.0f))); scene.getLastChild().attachChild(circles[i]); scene.registerUpdateHandler(physicsWorld);

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• Derive a algorithm to match best position

  - by Farooq Arshed

  I have pieces in my game which have stats and cost assigned to them and they can only be placed at a certain location. Lets say I have 50 pieces. e.g. Piece1 = 100 stats, 10 cost, Position A. Piece2 = 120 stats, 5 cost, Position B. Piece3 = 500 stats, 50 cost, Position C. Piece4 = 200 stats, 25 cost, Position A. and so on.. I have a board on which 12 pieces have to be allocated and have to remain inside the board cost. e.g. A board has A,B,C ... J,K,L positions and X Cost assigned to it. I have to figure out a way to place best possible piece in the correct position and should remain within the cost specified by the board. Any help would be appreciated.

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• as3 3D camera lookat

  - by Johannes Jensen

  I'm making a 3D camera scene in Flash, draw using drawTriangles() and rotated and translated using a Matrix3D. I've got the camera to look after a specific point, but only on the Y-axis, using the x and z coordinates, here is my code so far: var dx:Number = camera.x - lookAt.x; var dy:Number = camera.y - lookAt.y; var dz:Number = camera.z - lookAt.z; camera.rotationY = Math.atan2(dz, dx) * (180 / Math.PI) + 270; so no matter the x or z position, the point is always on the mid of the screen, IF and only if y matches with the camera. So what I need is to calculate the rotationX (which are measured in degrees not radians), and I was wondering how I would do this?

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• C# XNA: Effecient mesh building algorithm for voxel based terrain ("top" outside layer only, non-destructible)

  - by Tim Hatch

  To put this bluntly, for non-destructible/non-constructible voxel style terrain, are generated meshes handled much better than instancing? Is there another method to achieve millions of visible quad faces per scene with ease? If generated meshes per chunk is the way to go, what kind of algorithm might I want to use based on only EVER needing the outer layer rendered? I'm using 3D Perlin Noise for terrain generation (for overhangs/caves/etc). The layout is fantastic, but even for around 20k visible faces, it's quite slow using instancing (whether it's one big draw call or multiple smaller chunks). I've simplified it to the point of removing non-visible cubes and only having the top faces of my cube-like terrain be rendered, but with 20k quad instances, it's still pretty sluggish (30fps on my machine). My goal is for the world to be made using quite small cubes. Where multiple games (IE: Minecraft) have the player 1x1 cube in width/length and 2 high, I'm shooting for 6x6 width/length and 9 high. With a lot of advantages as far as gameplay goes, it also means I could quite easily have a single scene with millions of truly visible quads. So, I have been trying to look into changing my method from instancing to mesh generation on a chunk by chunk basis. Do video cards handle this type of processing better than separate quads/cubes through instancing? What kind of existing algorithms should I be looking into? I've seen references to marching cubes a few times now, but I haven't spent much time investigating it since I don't know if it's the better route for my situation or not. I'm also starting to doubt my need of using 3D Perlin noise for terrain generation since I won't want the kind of depth it would seem best at. I just like the idea of overhangs and occasional cave-like structures, but could find no better 'surface only' algorithms to cover that. If anyone has any better suggestions there, feel free to throw them at me too. Thanks, Mythics

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• How does this game loop actually work?

  - by Nicolai

  I read this playfulJS post, about ray-casting: http://www.playfuljs.com/a-first-person-engine-in-265-lines/ It looks really interested, so I decided to look at his javascript. I am no expert in javascript, so I quickly got lost. It's the game loop "object" that really gets me. I simply don't understand how it works. From the code: function GameLoop() { this.frame = this.frame.bind(this); this.lastTime = 0; this.callback = function() {}; } GameLoop.prototype.start = function(callback) { this.callback = callback; requestAnimationFrame(this.frame); }; GameLoop.prototype.frame = function(time) { var seconds = (time - this.lastTime) / 1000; this.lastTime = time; if (seconds < 0.2) this.callback(seconds); requestAnimationFrame(this.frame); }; var loop = new GameLoop(); loop.start(function frame(seconds) { map.update(seconds); player.update(controls.states, map, seconds); camera.render(player, map); }); Now, what really confuses me here, is this bind stuff and how this actually loops. I am guessing, that if less than 0.2 seconds have passed, since the last time the loop was run, it simply goes back to re-check the time. If more than 0.2 seconds have passed, it leaves the frame function, and executes the 3 lines in the loop. But, if this is true, then how does the loop.start() get called again? And what on earth is the meaning of this.frame = this.frame.bind(this);? I've looked up prototypes bind() but I really don't understand it.

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• Approaches to timed puzzle elements

  - by ndg

  I'm working on a side scrolling game that has a number of timed puzzle elements. As a simple example: I have a number of moving platforms that have been setup to transition in a pattern. Ideally I'd like to ensure that as the player first approaches them, they are in an ideal state -- whereby the player can witness the full transition and more experienced players (i.e: speedrunners) can complete the puzzle immediately without having to wait for the current transition to complete. The issue here, in a nutshell, is that because these platforms begin transitioning at the start of the level, it's impossible to correctly calculate when the player is likely to stumble upon them. I've done a fair bit of Googling but haven't managed to turn up any decent resources with regards to solving a problem like this. The obvious solution is to only begin updating the objects when the player (or more likely: the camera) first encounters them. But this becomes difficult when you consider more complicated situations. It seems like potentially the easiest way of handling this is to have an invisible trigger volume that will tell any puzzle elements located inside of it that the player has 'arrived' upon first colliding with the player. But this would mean I'd have to logically group puzzle elements, which could become fairly messy in a hurry. Take, for instance, a puzzle that appears to the right of the screen. It may take the player a number of seconds to reach it. It would look strange if the elements involved were to remain stationary. But by the time the player arrives, it's likely things will be 'out of sync'. I wanted to post here in the hopes that others know of, or have implemented, a decent solution to this problem?

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• UDK game Prisoners/Guards

  - by RR_1990

  For school I need to make a little game with UDK, the concept of the game is: The player is the headguard, he will have some other guard (bots) who will follow him. Between the other guards and the player are some prisoners who need to evade the other guards. It needs to look like this My idea was to let the guard bots follow the player at a certain distance and let the prisoners bots in the middle try to evade the guard bots. Now is the problem i'm new to Unreal Script and the school doesn't support me that well. Untill now I have only was able to make the guard bots follow me. I hope you guys can help me or make me something that will make this game work. Here is the class i'm using to let te bots follow me: class ChaseControllerAI extends AIController; var Pawn player; var float minimalDistance; var float speed; var float distanceToPlayer; var vector selfToPlayer; auto state Idle { function BeginState(Name PreviousStateName) { Super.BeginState(PreviousStateName); } event SeePlayer(Pawn p) { player = p; GotoState('Chase'); } Begin: player = none; self.Pawn.Velocity.x = 0.0; self.Pawn.Velocity.Y = 0.0; self.Pawn.Velocity.Z = 0.0; } state Chase { function BeginState(Name PreviousStateName) { Super.BeginState(PreviousStateName); } event PlayerOutOfReach() { `Log("ChaseControllerAI CHASE Player out of reach."); GotoState('Idle'); } // class ChaseController extends AIController; CONTINUED // State Chase (continued) event Tick(float deltaTime) { `Log("ChaseControllerAI in Event Tick."); selfToPlayer = self.player.Location - self.Pawn.Location; distanceToPlayer = Abs(VSize(selfToPlayer)); if (distanceToPlayer > minimalDistance) { PlayerOutOfReach(); } else { self.Pawn.Velocity = Normal(selfToPlayer) * speed; //self.Pawn.Acceleration = Normal(selfToPlayer) * speed; self.Pawn.SetRotation(rotator(selfToPlayer)); self.Pawn.Move(self.Pawn.Velocity*0.001); // or *deltaTime } } Begin: `Log("Current state Chase:Begin: " @GetStateName()@""); } defaultproperties { bAdjustFromWalls=true; bIsPlayer= true; minimalDistance = 1024; //org 1024 speed = 500; }

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• RenderTarget2D behavior in XNA

  - by Utkarsh Sinha

  I've been dabbling with XNA for a couple of days now. This chunk of code doesn't work as I expect. The goal is to render sprites individually and composite them on another rendertarget. P = RenderTarget2D(with RenderTargetUsage.PreserveContents) D = RenderTarget2D(with RenderTargetUsage.DiscardContents) for all sprites: graphicsDevice.SetRenderTarget(D); <draw sprite i> graphicsDevice.SetRenderTarget(P); <Draw D> graphicsDevice.SetRenderTarget(null); <Draw P> The result I get is - only the last sprite is visible. I'm sure I'm missing some piece of information about RenderTarget2D. Any hints on what that might be? Cross posted from - http://stackoverflow.com/questions/9970349/weird-rendertarget2d-behaviour

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• Why are my Unity procedural animations jerky?

  - by Phoenix Perry

  I'm working in Unity and getting some crazy weird motion behavior. I have a plane and I'm moving it. It's ever so slightly getting about 1 pixel bigger and smaller. It looks like the it's kind of getting squeezed sideways by a pixel. I'm moving a plane by cos and sin so it will spin on the x and z axes. If the planes are moving at Time.time, everything is fine. However, if I put in slower speed multiplier, I get an amazingly weird jerk in my animation. I get it with or without the lerp. How do I fix it? I want it to move very slowly. Is there some sort of invisible grid in unity? Some sort of minimum motion per frame? I put a visual sample of the behavior here. Here's the relevant code: public void spin() { for (int i = 0; i < numPlanes; i++ ) { GameObject g = planes[i] as GameObject; //alt method //currentRotation += speed * Time.deltaTime * 100; //rotation.eulerAngles = new Vector3(0, currentRotation, 0); //g.transform.position = rotation * rotationRadius; //sine method g.GetComponent<PlaneSetup>().pos.x = g.GetComponent<PlaneSetup>().radiusX * (Mathf.Cos((Time.time*speed) + g.GetComponent<PlaneSetup>().startAngle)); g.GetComponent<PlaneSetup>().pos.z = g.GetComponent<PlaneSetup>().radius * Mathf.Sin((Time.time*speed) + g.GetComponent<PlaneSetup>().startAngle); g.GetComponent<PlaneSetup>().pos.y = g.GetComponent<Transform>().position.y; ////offset g.GetComponent<PlaneSetup>().pos.z += 20; g.GetComponent<PlaneSetup>().posLerp.x = Mathf.Lerp(g.transform.position.x,g.GetComponent<PlaneSetup>().pos.x, .5f); g.GetComponent<PlaneSetup>().posLerp.z = Mathf.Lerp(g.transform.position.z, g.GetComponent<PlaneSetup>().pos.z, .5f); g.GetComponent<PlaneSetup>().posLerp.y = g.GetComponent<Transform>().position.y; g.transform.position = g.GetComponent<PlaneSetup>().posLerp; } Invoke("spin",0.0f); } The full code is on github. There is literally nothing else going on. I've turned off all other game objects so it's only the 40 planes with a texture2D shader. I removed it from Invoke and tried it in Update -- still happens. With a set frame rate or not, the same problem occurs. Tested it in Fixed Update. Same issue. The script on the individual plane doesn't even have an update function in it. The data on it could functionally live in a struct. I'm getting between 90 and 123 fps. Going to investigate and test further. I put this in an invoke function to see if I could get around it just occurring in update. There are no physics on these shapes. It's a straight procedural animation. Limited it to 1 plane - still happens. Thoughts? Removed the shader - still happening.

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• Vertex buffer acting strange? [on hold]

  - by Ryan Capote

  I'm having a strange problem, and I don't know what could be causing it. My current code is identical to how I've done this before. I'm trying to render a rectangle using VBO and orthographic projection.   My results:     What I expect: 3x3 rectangle in the top left corner   #include <stdio.h> #include <GL\glew.h> #include <GLFW\glfw3.h> #include "lodepng.h"   static const int FALSE = 0; static const int TRUE = 1;   static const char* VERT_SHADER =     "#version 330\n"       "layout(location=0) in vec4 VertexPosition; "     "layout(location=1) in vec2 UV;"     "uniform mat4 uProjectionMatrix;"     /*"out vec2 TexCoords;"*/       "void main(void) {"     "    gl_Position = uProjectionMatrix*VertexPosition;"     /*"    TexCoords = UV;"*/     "}";   static const char* FRAG_SHADER =     "#version 330\n"       /*"uniform sampler2D uDiffuseTexture;"     "uniform vec4 uColor;"     "in vec2 TexCoords;"*/     "out vec4 FragColor;"       "void main(void) {"    /* "    vec4 texel = texture2D(uDiffuseTexture, TexCoords);"     "    if(texel.a <= 0) {"     "         discard;"     "    }"     "    FragColor = texel;"*/     "    FragColor = vec4(1.f);"     "}";   static int g_running; static GLFWwindow *gl_window; static float gl_projectionMatrix[16];   /*     Structures */ typedef struct _Vertex {     float x, y, z, w;     float u, v; } Vertex;   typedef struct _Position {     float x, y; } Position;   typedef struct _Bitmap {     unsigned char *pixels;     unsigned int width, height; } Bitmap;   typedef struct _Texture {     GLuint id;     unsigned int width, height; } Texture;   typedef struct _VertexBuffer {     GLuint bufferObj, vertexArray; } VertexBuffer;   typedef struct _ShaderProgram {     GLuint vertexShader, fragmentShader, program; } ShaderProgram;   /*   http://en.wikipedia.org/wiki/Orthographic_projection */ void createOrthoProjection(float *projection, float width, float height, float far, float near)  {       const float left = 0;     const float right = width;     const float top = 0;     const float bottom = height;          projection[0] = 2.f / (right - left);     projection[1] = 0.f;     projection[2] = 0.f;     projection[3] = -(right+left) / (right-left);     projection[4] = 0.f;     projection[5] = 2.f / (top - bottom);     projection[6] = 0.f;     projection[7] = -(top + bottom) / (top - bottom);     projection[8] = 0.f;     projection[9] = 0.f;     projection[10] = -2.f / (far-near);     projection[11] = (far+near)/(far-near);     projection[12] = 0.f;     projection[13] = 0.f;     projection[14] = 0.f;     projection[15] = 1.f; }   /*     Textures */ void loadBitmap(const char *filename, Bitmap *bitmap, int *success) {     int error = lodepng_decode32_file(&bitmap->pixels, &bitmap->width, &bitmap->height, filename);       if (error != 0) {         printf("Failed to load bitmap. ");         printf(lodepng_error_text(error));         success = FALSE;         return;     } }   void destroyBitmap(Bitmap *bitmap) {     free(bitmap->pixels); }   void createTexture(Texture *texture, const Bitmap *bitmap) {     texture->id = 0;     glGenTextures(1, &texture->id);     glBindTexture(GL_TEXTURE_2D, texture);       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bitmap->width, bitmap->height, 0,              GL_RGBA, GL_UNSIGNED_BYTE, bitmap->pixels);       glBindTexture(GL_TEXTURE_2D, 0); }   void destroyTexture(Texture *texture) {     glDeleteTextures(1, &texture->id);     texture->id = 0; }   /*     Vertex Buffer */ void createVertexBuffer(VertexBuffer *vertexBuffer, Vertex *vertices) {     glGenBuffers(1, &vertexBuffer->bufferObj);     glGenVertexArrays(1, &vertexBuffer->vertexArray);     glBindVertexArray(vertexBuffer->vertexArray);       glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj);     glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 6, (const GLvoid*)vertices, GL_STATIC_DRAW);       const unsigned int uvOffset = sizeof(float) * 4;       glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);     glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)uvOffset);       glEnableVertexAttribArray(0);     glEnableVertexAttribArray(1);       glBindBuffer(GL_ARRAY_BUFFER, 0);     glBindVertexArray(0); }   void destroyVertexBuffer(VertexBuffer *vertexBuffer) {     glDeleteBuffers(1, &vertexBuffer->bufferObj);     glDeleteVertexArrays(1, &vertexBuffer->vertexArray); }   void bindVertexBuffer(VertexBuffer *vertexBuffer) {     glBindVertexArray(vertexBuffer->vertexArray);     glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); }   void drawVertexBufferMode(GLenum mode) {     glDrawArrays(mode, 0, 6); }   void drawVertexBuffer() {     drawVertexBufferMode(GL_TRIANGLES); }   void unbindVertexBuffer() {     glBindVertexArray(0);     glBindBuffer(GL_ARRAY_BUFFER, 0); }   /*     Shaders */ void compileShader(ShaderProgram *shaderProgram, const char *vertexSrc, const char *fragSrc) {     GLenum err;     shaderProgram->vertexShader = glCreateShader(GL_VERTEX_SHADER);     shaderProgram->fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);       if (shaderProgram->vertexShader == 0) {         printf("Failed to create vertex shader.");         return;     }       if (shaderProgram->fragmentShader == 0) {         printf("Failed to create fragment shader.");         return;     }       glShaderSource(shaderProgram->vertexShader, 1, &vertexSrc, NULL);     glCompileShader(shaderProgram->vertexShader);     glGetShaderiv(shaderProgram->vertexShader, GL_COMPILE_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to compile vertex shader.");         return;     }       glShaderSource(shaderProgram->fragmentShader, 1, &fragSrc, NULL);     glCompileShader(shaderProgram->fragmentShader);     glGetShaderiv(shaderProgram->fragmentShader, GL_COMPILE_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to compile fragment shader.");         return;     }       shaderProgram->program = glCreateProgram();     glAttachShader(shaderProgram->program, shaderProgram->vertexShader);     glAttachShader(shaderProgram->program, shaderProgram->fragmentShader);     glLinkProgram(shaderProgram->program);          glGetProgramiv(shaderProgram->program, GL_LINK_STATUS, &err);       if (err != GL_TRUE) {         printf("Failed to link shader.");         return;     } }   void destroyShader(ShaderProgram *shaderProgram) {     glDetachShader(shaderProgram->program, shaderProgram->vertexShader);     glDetachShader(shaderProgram->program, shaderProgram->fragmentShader);       glDeleteShader(shaderProgram->vertexShader);     glDeleteShader(shaderProgram->fragmentShader);       glDeleteProgram(shaderProgram->program); }   GLuint getUniformLocation(const char *name, ShaderProgram *program) {     GLuint result = 0;     result = glGetUniformLocation(program->program, name);       return result; }   void setUniformMatrix(float *matrix, const char *name, ShaderProgram *program) {     GLuint loc = getUniformLocation(name, program);       if (loc == -1) {         printf("Failed to get uniform location in setUniformMatrix.\n");         return;     }       glUniformMatrix4fv(loc, 1, GL_FALSE, matrix); }   /*     General functions */ static int isRunning() {     return g_running && !glfwWindowShouldClose(gl_window); }   static void initializeGLFW(GLFWwindow **window, int width, int height, int *success) {     if (!glfwInit()) {         printf("Failed it inialize GLFW.");         *success = FALSE;        return;     }          glfwWindowHint(GLFW_RESIZABLE, 0);     *window = glfwCreateWindow(width, height, "Alignments", NULL, NULL);          if (!*window) {         printf("Failed to create window.");         glfwTerminate();         *success = FALSE;         return;     }          glfwMakeContextCurrent(*window);       GLenum glewErr = glewInit();     if (glewErr != GLEW_OK) {         printf("Failed to initialize GLEW.");         printf(glewGetErrorString(glewErr));         *success = FALSE;         return;     }       glClearColor(0.f, 0.f, 0.f, 1.f);     glViewport(0, 0, width, height);     *success = TRUE; }   int main(int argc, char **argv) {          int err = FALSE;     initializeGLFW(&gl_window, 480, 320, &err);     glDisable(GL_DEPTH_TEST);     if (err == FALSE) {         return 1;     }          createOrthoProjection(gl_projectionMatrix, 480.f, 320.f, 0.f, 1.f);          g_running = TRUE;          ShaderProgram shader;     compileShader(&shader, VERT_SHADER, FRAG_SHADER);     glUseProgram(shader.program);     setUniformMatrix(&gl_projectionMatrix, "uProjectionMatrix", &shader);       Vertex rectangle[6];     VertexBuffer vbo;     rectangle[0] = (Vertex){0.f, 0.f, 0.f, 1.f, 0.f, 0.f}; // Top left     rectangle[1] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top right     rectangle[2] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left     rectangle[3] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top left     rectangle[4] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left     rectangle[5] = (Vertex){3.f, 3.f, 0.f, 1.f, 1.f, 1.f}; // Bottom right       createVertexBuffer(&vbo, &rectangle);            bindVertexBuffer(&vbo);          while (isRunning()) {         glClear(GL_COLOR_BUFFER_BIT);         glfwPollEvents();                    drawVertexBuffer();                    glfwSwapBuffers(gl_window);     }          unbindVertexBuffer(&vbo);       glUseProgram(0);     destroyShader(&shader);     destroyVertexBuffer(&vbo);     glfwTerminate();     return 0; }

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• Implementing camera for 2d side scroller game ?

  - by Mr.Gando

  Hello, I'm implementing a 2D side scroller for iOS (using C/C++ with OpenGL) (beat'em up style like double dragon/final fight ). My scenes are composed of one cyclical background image ( the end of the image connects perfectly with the beginning ). This is to produce a cyclical scroll effect. I was wondering how could I implement a camera that follows my player movement ? ( Resources / Links are greatly appreciated with explanations :) )

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• Clientside anticheating in multiplayer game 1vs1

  - by garnav

  I'm developing a simple card game, where there will be a matchmaking system that will put you against another human player. This will be the only game mode available, a 1vs1 against another human, no AI. I want to prevent cheating as much as possible. I have already read a lot of similar questions here and I already know that I cannot trust the client and I have to make all verifications server side. I intend to have a server (need one for the matchmaking anyway) and I intend to make some verifications server side but if I want to check everything server side this makes my server to be able to keep track of the state of all current games and check every action, and I don't have the money/infrastructure to support that server. My idea is to make clients check and verify some of the actions made by their opponent* and if they find some illegal action notify the possible cheating to the server and make the server verify it. This will still require my server to keep track of all current games, but it will save resources only checking some things that cannot be checked at client side(like card order in the deck) and only checking other things when they are actually wrong. *(only those they can check with out allowing themselves cheating! for example:they can't check if the played card was in hand cos that will need them to know all cards in hand) Summing up, my questions are: is this a viable approach? will I actually save resources doing this or the extra complexity in the server and client for exchanging this messages is not worth it? do you know any game that has successfully or unsuccessfully tried a similar approach? Thanks all for reading and answering

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• Normal maps red in OpenGL?

  - by KaiserJohaan

  I am using Assimp to import 3d models, and FreeImage to parse textures. The problem I am having is that the normal maps are actually red rather than blue when I try to render them as normal diffuse textures. http://i42.tinypic.com/289ing3.png When I open the images in a image-viewing program they do indeed show up as blue. Heres when I create the texture; OpenGLTexture::OpenGLTexture(const std::vector<uint8_t>& textureData, uint32_t textureWidth, uint32_t textureHeight, TextureType textureType, Logger& logger) : mLogger(logger), mTextureID(gNextTextureID++), mTextureType(textureType) { glGenTextures(1, &mTexture); CHECK_GL_ERROR(mLogger); glBindTexture(GL_TEXTURE_2D, mTexture); CHECK_GL_ERROR(mLogger); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, textureWidth, textureHeight, 0, glTextureFormat, GL_UNSIGNED_BYTE, &textureData[0]); CHECK_GL_ERROR(mLogger); glGenerateMipmap(GL_TEXTURE_2D); CHECK_GL_ERROR(mLogger); glBindTexture(GL_TEXTURE_2D, 0); CHECK_GL_ERROR(mLogger); } Here is my fragment shader. You can see I just commented out the normal-map parsing and treated the normal map texture as the diffuse texture to display it and illustrate the problem. As for the rest of the code it interacts as expected with the diffuse textures so I dont see a obvious problem there. "#version 330 \n \ \n \ layout(std140) uniform; \n \ \n \ const int MAX_LIGHTS = 8; \n \ \n \ struct Light \n \ { \n \ vec4 mLightColor; \n \ vec4 mLightPosition; \n \ vec4 mLightDirection; \n \ \n \ int mLightType; \n \ float mLightIntensity; \n \ float mLightRadius; \n \ float mMaxDistance; \n \ }; \n \ \n \ uniform UnifLighting \n \ { \n \ vec4 mGamma; \n \ vec3 mViewDirection; \n \ int mNumLights; \n \ \n \ Light mLights[MAX_LIGHTS]; \n \ } Lighting; \n \ \n \ uniform UnifMaterial \n \ { \n \ vec4 mDiffuseColor; \n \ vec4 mAmbientColor; \n \ vec4 mSpecularColor; \n \ vec4 mEmissiveColor; \n \ \n \ bool mHasDiffuseTexture; \n \ bool mHasNormalTexture; \n \ bool mLightingEnabled; \n \ float mSpecularShininess; \n \ } Material; \n \ \n \ uniform sampler2D unifDiffuseTexture; \n \ uniform sampler2D unifNormalTexture; \n \ \n \ in vec3 frag_position; \n \ in vec3 frag_normal; \n \ in vec2 frag_texcoord; \n \ in vec3 frag_tangent; \n \ in vec3 frag_bitangent; \n \ \n \ out vec4 finalColor; " " \n \ \n \ void CalcGaussianSpecular(in vec3 dirToLight, in vec3 normal, out float gaussianTerm) \n \ { \n \ vec3 viewDirection = normalize(Lighting.mViewDirection); \n \ vec3 halfAngle = normalize(dirToLight + viewDirection); \n \ \n \ float angleNormalHalf = acos(dot(halfAngle, normalize(normal))); \n \ float exponent = angleNormalHalf / Material.mSpecularShininess; \n \ exponent = -(exponent * exponent); \n \ \n \ gaussianTerm = exp(exponent); \n \ } \n \ \n \ vec4 CalculateLighting(in Light light, in vec4 diffuseTexture, in vec3 normal) \n \ { \n \ if (light.mLightType == 1) // point light \n \ { \n \ vec3 positionDiff = light.mLightPosition.xyz - frag_position; \n \ float dist = max(length(positionDiff) - light.mLightRadius, 0); \n \ \n \ float attenuation = 1 / ((dist/light.mLightRadius + 1) * (dist/light.mLightRadius + 1)); \n \ attenuation = max((attenuation - light.mMaxDistance) / (1 - light.mMaxDistance), 0); \n \ \n \ vec3 dirToLight = normalize(positionDiff); \n \ float angleNormal = clamp(dot(normalize(normal), dirToLight), 0, 1); \n \ \n \ float gaussianTerm = 0.0; \n \ if (angleNormal > 0.0) \n \ CalcGaussianSpecular(dirToLight, normal, gaussianTerm); \n \ \n \ return diffuseTexture * (attenuation * angleNormal * Material.mDiffuseColor * light.mLightIntensity * light.mLightColor) + \n \ (attenuation * gaussianTerm * Material.mSpecularColor * light.mLightIntensity * light.mLightColor); \n \ } \n \ else if (light.mLightType == 2) // directional light \n \ { \n \ vec3 dirToLight = normalize(light.mLightDirection.xyz); \n \ float angleNormal = clamp(dot(normalize(normal), dirToLight), 0, 1); \n \ \n \ float gaussianTerm = 0.0; \n \ if (angleNormal > 0.0) \n \ CalcGaussianSpecular(dirToLight, normal, gaussianTerm); \n \ \n \ return diffuseTexture * (angleNormal * Material.mDiffuseColor * light.mLightIntensity * light.mLightColor) + \n \ (gaussianTerm * Material.mSpecularColor * light.mLightIntensity * light.mLightColor); \n \ } \n \ else if (light.mLightType == 4) // ambient light \n \ return diffuseTexture * Material.mAmbientColor * light.mLightIntensity * light.mLightColor; \n \ else \n \ return vec4(0.0); \n \ } \n \ \n \ void main() \n \ { \n \ vec4 diffuseTexture = vec4(1.0); \n \ if (Material.mHasDiffuseTexture) \n \ diffuseTexture = texture(unifDiffuseTexture, frag_texcoord); \n \ \n \ vec3 normal = frag_normal; \n \ if (Material.mHasNormalTexture) \n \ { \n \ diffuseTexture = vec4(normalize(texture(unifNormalTexture, frag_texcoord).xyz * 2.0 - 1.0), 1.0); \n \ // vec3 normalTangentSpace = normalize(texture(unifNormalTexture, frag_texcoord).xyz * 2.0 - 1.0); \n \ //mat3 tangentToWorldSpace = mat3(normalize(frag_tangent), normalize(frag_bitangent), normalize(frag_normal)); \n \ \n \ // normal = tangentToWorldSpace * normalTangentSpace; \n \ } \n \ \n \ if (Material.mLightingEnabled) \n \ { \n \ vec4 accumLighting = vec4(0.0); \n \ \n \ for (int lightIndex = 0; lightIndex < Lighting.mNumLights; lightIndex++) \n \ accumLighting += Material.mEmissiveColor * diffuseTexture + \n \ CalculateLighting(Lighting.mLights[lightIndex], diffuseTexture, normal); \n \ \n \ finalColor = pow(accumLighting, Lighting.mGamma); \n \ } \n \ else { \n \ finalColor = pow(diffuseTexture, Lighting.mGamma); \n \ } \n \ } \n"; Why is this? does normal-map textures need some sort of special treatment in opengl?

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• How to slow down a sprite that updates every frame?

  - by xiaohouzi79

  I am going through a Allegro 5 tutorial which has a game loop. There is also a variable "active" which determines if a key is being held down. Thus if the left key is being held down active is on and it begins looping through the row on the sprite sheet that corresponds to moving left. The problem is that this logic is checked everytime the loop is performed thus at approximately 60 fps the three images that are used to do the left walking animation cycle round super fast which means my character looks like it is in a rush. Total beginner question: so what is the correct way to slow down the transition between sprites so that the walking looks like it is done at a moderate pace. Here is the code used to transition across the sprite between the three different phases of the person walking: if (active) { sourceX += al_get_bitmap_width(player) / 3; } else { sourceX = 32; } if (sourceX >= al_get_bitmap_width(player)) { sourceX = 0; } I can kind of guess what it should be in plain English: update sourceX only every certain part of a second but I can't think of how to put this into code.

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• 2D Selective Gaussian Blur

  - by Joshua Thomas

  I am attempting to use Gaussian blur on a 2D platform game, selectively blurring specific types of platforms with different amounts. I am currently just messing around with simple test code, trying to get it to work correctly. What I need to eventually do is create three separate render targets, leave one normal, blur one slightly, and blur the last heavily, then recombine on the screen. Where I am now is I have successfully drawn into a new render target and performed the gaussian blur on it, but when I draw it back to the screen everything is purple aside from the platforms I drew to the target. This is my .fx file: #define RADIUS 7 #define KERNEL_SIZE (RADIUS * 2 + 1) //----------------------------------------------------------------------------- // Globals. //----------------------------------------------------------------------------- float weights[KERNEL_SIZE]; float2 offsets[KERNEL_SIZE]; //----------------------------------------------------------------------------- // Textures. //----------------------------------------------------------------------------- texture colorMapTexture; sampler2D colorMap = sampler_state { Texture = <colorMapTexture>; MipFilter = Linear; MinFilter = Linear; MagFilter = Linear; }; //----------------------------------------------------------------------------- // Pixel Shaders. //----------------------------------------------------------------------------- float4 PS_GaussianBlur(float2 texCoord : TEXCOORD) : COLOR0 { float4 color = float4(0.0f, 0.0f, 0.0f, 0.0f); for (int i = 0; i < KERNEL_SIZE; ++i) color += tex2D(colorMap, texCoord + offsets[i]) * weights[i]; return color; } //----------------------------------------------------------------------------- // Techniques. //----------------------------------------------------------------------------- technique GaussianBlur { pass { PixelShader = compile ps_2_0 PS_GaussianBlur(); } } This is the code I'm using for the gaussian blur: public Texture2D PerformGaussianBlur(Texture2D srcTexture, RenderTarget2D renderTarget1, RenderTarget2D renderTarget2, SpriteBatch spriteBatch) { if (effect == null) throw new InvalidOperationException("GaussianBlur.fx effect not loaded."); Texture2D outputTexture = null; Rectangle srcRect = new Rectangle(0, 0, srcTexture.Width, srcTexture.Height); Rectangle destRect1 = new Rectangle(0, 0, renderTarget1.Width, renderTarget1.Height); Rectangle destRect2 = new Rectangle(0, 0, renderTarget2.Width, renderTarget2.Height); // Perform horizontal Gaussian blur. game.GraphicsDevice.SetRenderTarget(renderTarget1); effect.CurrentTechnique = effect.Techniques["GaussianBlur"]; effect.Parameters["weights"].SetValue(kernel); effect.Parameters["colorMapTexture"].SetValue(srcTexture); effect.Parameters["offsets"].SetValue(offsetsHoriz); spriteBatch.Begin(0, BlendState.Opaque, null, null, null, effect); spriteBatch.Draw(srcTexture, destRect1, Color.White); spriteBatch.End(); // Perform vertical Gaussian blur. game.GraphicsDevice.SetRenderTarget(renderTarget2); outputTexture = (Texture2D)renderTarget1; effect.Parameters["colorMapTexture"].SetValue(outputTexture); effect.Parameters["offsets"].SetValue(offsetsVert); spriteBatch.Begin(0, BlendState.Opaque, null, null, null, effect); spriteBatch.Draw(outputTexture, destRect2, Color.White); spriteBatch.End(); // Return the Gaussian blurred texture. game.GraphicsDevice.SetRenderTarget(null); outputTexture = (Texture2D)renderTarget2; return outputTexture; } And this is the draw method affected: public void Draw(SpriteBatch spriteBatch) { device.SetRenderTarget(maxBlur); spriteBatch.Begin(); foreach (Brick brick in blueBricks) brick.Draw(spriteBatch); spriteBatch.End(); blue = gBlur.PerformGaussianBlur((Texture2D) maxBlur, helperTarget, maxBlur, spriteBatch); spriteBatch.Begin(); device.SetRenderTarget(null); foreach (Brick brick in redBricks) brick.Draw(spriteBatch); foreach (Brick brick in greenBricks) brick.Draw(spriteBatch); spriteBatch.Draw(blue, new Rectangle(0, 0, blue.Width, blue.Height), Color.White); foreach (Brick brick in purpleBricks) brick.Draw(spriteBatch); spriteBatch.End(); } I'm sorry about the massive brick of text and images(or not....new user, I tried, it said no), but I wanted to get my problem across clearly as I have been searching for an answer to this for quite a while now. As a side note, I have seen the bloom sample. Very well commented, but overly complicated since it deals in 3D; I was unable to take what I needed to learn form it. Thanks for any and all help.

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• Out of Memory when building an application

  - by Jacob Neal

  I have quite a major problem with my Multimedia Fusion 2 game. I finished it months ago, however, the only thing keeping me from finally compiling the game into an executable file is this error message that pops up every time I try to, simply saying, "Out of Memory". Its highly frustrating to be halted at this point by this message, and I tried everything I could come up with to fix it including compressing the runtime and sounds and increasing the proity of MMF2 all the way to realtime in the task manager. Im begging someone to toss me a bone on this problem, and any advice at all would be much appreciated.

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• cocos2d: syncing CCAnimation frames with Box2d Shape manipulations

  - by Hezi Cohen

  hi everybody! my cocos2d game currently has a ccsprite attached to a box2d body. during the game i apply different CCAnimations on my sprite, i would like to perform certain manipulations to the box2d body according to the frame currently displayed by the sprite (change rotation of the body, etc.) my current idea on implementing this is to subclass ccsprite and change the setDisplayFrame implementation but i thought somebody here probably did the same and already has a solution, so any suggestions on how to implement this? thanks!

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• Optimizing graphics for an iOS flash game

  - by 1GR3

  A friend of mine and myself are working on a flash developed iOS (and later Android) puzzle board game. He's a developer and I'm a designer/developer so (no surprise) we have different points of view. His method: make small tiles (100x100px) in Photoshop join them into the board and then in flash apply effects to the board to avoid repetition (80's not in the good way). My method: precompose the whole board (960x640px+bleed) in Photoshop and than mask active and inactive areas in flash. What do you think?

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• SlimDX and Parsing .X Files

  - by P. Avery

  I'm trying to parse a .x file using SlimDX. I can create the XFile object and register templates but I'm having problems with the enumeration object. The enumeration object has a child count of 0 for a file I know to have valid data. Here is code to create file, enumeration, and data objects: public void Parse(string filename, string templates, ref Frame aParam) { XFile xfile = null; XFileEnumerationObject enumObj = null; XFileData dataObj = null; // create file object xfile = new XFile(); // register templates if (xfile.RegisterTemplates(XFile.DefaultTemplates).IsFailure) { Console.WriteLine(Result.Last); xfile.Dispose(); return; } // create enumeration object enumObj = xfile.CreateEnumerationObject(filename, System.Runtime.InteropServices.CharSet.Auto); if (enumObj == null) { xfile.Dispose(); return; } // get child count( returns 0 here ) long ncElements = enumObj.ChildCount; for (int i = 0; i < ncElements; ++i) { // never reached... dataObj = enumObj.GetChild(i); if (dataObj.IsReference) continue; try { Parse(dataObj, ref aParam); } catch (Exception e) { e.Write(); } finally { dataObj.Dispose(); } } enumObj.Dispose(); xfile.Dispose(); } ...There are no exceptions thrown by this function...the child count is 0 so the conditional loop breaks right away, the file objects are disposed of and the function returns... Here is .x file...a simple cube: xof 0303txt 0032 Frame Root { FrameTransformMatrix { 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000;; } Frame Cube { FrameTransformMatrix { 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000;; } Mesh Cube{ //Cube Mesh 36; -1.000000; 1.000000; 1.000000;, -1.000000;-1.000000; 1.000000;, 0.999999;-1.000001; 1.000000;, -1.000000;-1.000000;-1.000000;, 1.000000;-1.000000;-1.000000;, 0.999999;-1.000001; 1.000000;, 1.000000; 0.999999; 1.000000;, -1.000000; 1.000000; 1.000000;, 0.999999;-1.000001; 1.000000;, -1.000000; 1.000000;-1.000000;, -1.000000;-1.000000;-1.000000;, -1.000000; 1.000000; 1.000000;, -1.000000; 1.000000; 1.000000;, 1.000000; 0.999999; 1.000000;, 1.000000; 1.000000;-1.000000;, 1.000000; 0.999999; 1.000000;, 0.999999;-1.000001; 1.000000;, 1.000000;-1.000000;-1.000000;, -1.000000;-1.000000;-1.000000;, -1.000000;-1.000000; 1.000000;, -1.000000; 1.000000; 1.000000;, 1.000000; 1.000000;-1.000000;, 1.000000;-1.000000;-1.000000;, -1.000000; 1.000000;-1.000000;, 1.000000; 1.000000;-1.000000;, 1.000000; 0.999999; 1.000000;, 1.000000;-1.000000;-1.000000;, -1.000000; 1.000000;-1.000000;, -1.000000; 1.000000; 1.000000;, 1.000000; 1.000000;-1.000000;, -1.000000;-1.000000; 1.000000;, -1.000000;-1.000000;-1.000000;, 0.999999;-1.000001; 1.000000;, 1.000000;-1.000000;-1.000000;, -1.000000;-1.000000;-1.000000;, -1.000000; 1.000000;-1.000000;; 12; 3;0;1;2;, 3;3;4;5;, 3;6;7;8;, 3;9;10;11;, 3;12;13;14;, 3;15;16;17;, 3;18;19;20;, 3;21;22;23;, 3;24;25;26;, 3;27;28;29;, 3;30;31;32;, 3;33;34;35;; MeshNormals { //Mesh Normals 36; 0.000000;-0.000000; 1.000000;, 0.000000;-0.000000; 1.000000;, 0.000000;-0.000000; 1.000000;, -0.000000;-1.000000;-0.000000;, -0.000000;-1.000000;-0.000000;, -0.000000;-1.000000;-0.000000;, -0.000000;-0.000000; 1.000000;, -0.000000;-0.000000; 1.000000;, -0.000000;-0.000000; 1.000000;, -1.000000; 0.000000;-0.000000;, -1.000000; 0.000000;-0.000000;, -1.000000; 0.000000;-0.000000;, 0.000000; 1.000000; 0.000000;, 0.000000; 1.000000; 0.000000;, 0.000000; 1.000000; 0.000000;, 1.000000;-0.000001; 0.000000;, 1.000000;-0.000001; 0.000000;, 1.000000;-0.000001; 0.000000;, -1.000000; 0.000000;-0.000000;, -1.000000; 0.000000;-0.000000;, -1.000000; 0.000000;-0.000000;, 0.000000; 0.000000;-1.000000;, 0.000000; 0.000000;-1.000000;, 0.000000; 0.000000;-1.000000;, 1.000000; 0.000000;-0.000000;, 1.000000; 0.000000;-0.000000;, 1.000000; 0.000000;-0.000000;, 0.000000; 1.000000; 0.000000;, 0.000000; 1.000000; 0.000000;, 0.000000; 1.000000; 0.000000;, -0.000000;-1.000000; 0.000000;, -0.000000;-1.000000; 0.000000;, -0.000000;-1.000000; 0.000000;, 0.000000;-0.000000;-1.000000;, 0.000000;-0.000000;-1.000000;, 0.000000;-0.000000;-1.000000;; 12; 3;0;1;2;, 3;3;4;5;, 3;6;7;8;, 3;9;10;11;, 3;12;13;14;, 3;15;16;17;, 3;18;19;20;, 3;21;22;23;, 3;24;25;26;, 3;27;28;29;, 3;30;31;32;, 3;33;34;35;; } //End of Mesh Normals MeshMaterialList { //Mesh Material List 1; 12; 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0;; Material Material { 0.640000; 0.640000; 0.640000; 1.000000;; 96.078431; 0.500000; 0.500000; 0.500000;; 0.000000; 0.000000; 0.000000;; TextureFilename {"Yellow.jpg";} } } //End of Mesh Material List MeshTextureCoords UVMap{ //Mesh UV Coordinates 36; 0.000000; 1.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 1.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 0.000000;, 0.000000; 1.000000;, 1.000000; 1.000000;, 1.000000; 0.000000;; } //End of Mesh UV Coordinates } //End of Mesh Mesh } //End of Cube } //End of Root Frame

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• Thread safe double buffering

  - by kdavis8

  I am trying to implement a draw map method that will draw the tiled image across the surface of the component. I'm having issue with this code. The double buffering does not seem to be working, because the sprite flickers like crazy; my source code: package myPackage; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; public class GameView extends JFrame implements Runnable { public BufferedImage backbuffer; public Graphics2D g2d; public Image img; Thread gameloop; Scene scene; public GameView() { super("Game View"); setSize(600, 600); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); backbuffer = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); Toolkit tk = Toolkit.getDefaultToolkit(); img = tk.getImage(this.getClass().getResource("cage.png")); scene = new Scene(g2d, this); gameloop = new Thread(this); gameloop.start(); } public static void main(String args[]) { new GameView(); } public void paint(Graphics g) { g.drawImage(backbuffer, 0, 0, this); repaint(); } @Override public void run() { // TODO Auto-generated method stub Thread t = Thread.currentThread(); while (t == gameloop) { scene.getScene("dirtmap"); g2d.drawImage(img, 80, 80,this![enter image description here][1]); } } private void drawScene(String string) { // TODO Auto-generated method stub // g2d.setColor(Color.white); // g2d.fillRect(0, 0, getWidth(), getHeight()); scene.getScene(string); } } package myPackage; import java.awt.Color; import java.awt.Component; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; public class Scene { Graphics g2d; Component c; boolean loaded = false; public Scene(Graphics2D gr, Component co) { g2d = gr; c = co; } public void getScene(String mapName) { Toolkit tk = Toolkit.getDefaultToolkit(); Image tile = tk.getImage(this.getClass().getResource("dirt.png")); // g2d.setColor(Color.red); for (int y = 0; y <= 18; y++) { for (int x = 0; x <= 18; x += 1) { g2d.drawImage(tile, x * 32, y * 32, c); } } loaded = true; } }

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• Using virtual functions

  - by Tucker Morgan

  I am starting to use virtual functions, and i am programming a simple text game, my question is this, if i have a virtual function called spec_abil with in a Super class called rpg_class. If you allow the player to class what class they want to play, say a mage class, a archer class, and a warrior class, which all have their own spec_abil function. How do you write it so that the program knows which one to use depending on the chosen class.

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• Collision Detection Game Design and Architecture

  - by Chompas

  I've reading some articles about collision detection. My question here is about ideas on the design for it. Baically I have a C++ game that has a main loop with entities with an update method. Based on keyboard input, these characters updates their positions. My question is not about how to detect collisions, it's about getting ideas in which is the best way to implement this. The game has a main character but also enemies that have to collide between them, so I'm not sure where to make all the iterations for checking collisions and if the right way is to check everything against everything. Thanks in advance.

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• Calculate the Intersection of Two Volumes

  - by igrad

  If you've ever played The Swapper, you'll have a good idea of what I'm asking about. I need to check for, and isolate, areas of a rectangle that may intersect with either a circle or another rectangle. These selected areas will receive special properties, and the areas will be non-static, since the intersecting shapes themselves will also be dynamic. My first thought was to use raycasting detection, though I've only seen that in use with circles, or even ellipses. I'm curious if there's a method of using raycasting with a more rectangular approach, or if there's a totally different method already in use to accomplish this task. I would like something more exact than checking in large chunks, and since I'm using SDL2 with a logical renderer size of 1920x1080, checking if each pixel is intersecting is out of the question, as it would slow things down past a playable speed. I already have a multi-shape collision function-template in place, and I could use that, though it only checks if sides or corners are intersecting; it does not compute the overlapping area, or even find the circle's secant line, though I can't imagine it would be overly complex to implement. TL;DR: I need to find and isolate areas of a rectangle that may intersect with a circle or another rectangle without checking every single pixel on-screen.

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• JOGL hardware based shadow mapping - computing the texture matrix

  - by axel22

  I am implementing hardware shadow mapping as described here. I've rendered the scene successfully from the light POV, and loaded the depth buffer of the scene into a texture. This texture has correctly been loaded - I check this by rendering a small thumbnail, as you can see in the screenshot below, upper left corner. The depth of the scene appears to be correct - objects further away are darker, and that are closer to the light are lighter. However, I run into trouble while rendering the scene from the camera's point of view using the depth texture - the texture on the polygons in the scene is rendered in a weird, nondeterministic fashion, as shown in the screenshot. I believe I am making an error while computing the texture transformation matrix, but I am unsure where exactly. Since I have no matrix utilities in JOGL other then the gl[Load|Mult]Matrix procedures, I multiply the matrices using them, like this: void calcTextureMatrix() { glPushMatrix(); glLoadIdentity(); glLoadMatrixf(biasmatrix, 0); glMultMatrixf(lightprojmatrix, 0); glMultMatrixf(lightviewmatrix, 0); glGetFloatv(GL_MODELVIEW_MATRIX, shadowtexmatrix, 0); glPopMatrix(); } I obtained these matrices by using the glOrtho and gluLookAt procedures: glLoadIdentity() val wdt = width / 45 val hgt = height / 45 glOrtho(wdt, -wdt, -hgt, hgt, -45.0, 45.0) glGetFloatv(GL_MODELVIEW_MATRIX, lightprojmatrix, 0) glLoadIdentity() glu.gluLookAt( xlook + lightpos._1, ylook + lightpos._2, lightpos._3, xlook, ylook, 0.0f, 0.f, 0.f, 1.0f) glGetFloatv(GL_MODELVIEW_MATRIX, lightviewmatrix, 0) My bias matrix is: float[] biasmatrix = new float[16] { 0.5f, 0.f, 0.f, 0.f, 0.f, 0.5f, 0.f, 0.f, 0.f, 0.f, 0.5f, 0.f, 0.5f, 0.5f, 0.5f, 1.f } After applying the camera projection and view matrices, I do: glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR) glTexGenfv(GL_S, GL_EYE_PLANE, shadowtexmatrix, 0) glEnable(GL_TEXTURE_GEN_S) for each component. Does anybody know why the texture is not being rendered correctly? Thank you.

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• Sliding collision response

  - by dbostream

  I have been reading plenty of tutorials about sliding collision responses yet I am not able to implement it properly in my project. What I want to do is make a puck slide along the rounded corner boards of a hockey rink. In my latest attempt the puck does slide along the boards but there are some strange velocity behaviors. First of all the puck slows down a lot pretty much right away and then it slides for awhile and stops before exiting the corner. Even if I double the speed I get a similar behavior and the puck does not make it out of the corner. I used some ideas from this document http://www.peroxide.dk/papers/collision/collision.pdf. This is what I have: Update method called from the game loop when it is time to update the puck (I removed some irrelevant parts). I use two states (current, previous) which are used to interpolate the position during rendering. public override void Update(double fixedTimeStep) { /* Acceleration is set to 0 for now. */ Acceleration.Zero(); PreviousState = CurrentState; _collisionRecursionDepth = 0; CurrentState.Position = SlidingCollision(CurrentState.Position, CurrentState.Velocity * fixedTimeStep + 0.5 * Acceleration * fixedTimeStep * fixedTimeStep); /* Should not this be affected by a sliding collision? and not only the position. */ CurrentState.Velocity = CurrentState.Velocity + Acceleration * fixedTimeStep; Heading = Vector2.NormalizeRet(CurrentState.Velocity); } private Vector2 SlidingCollision(Vector2 position, Vector2 velocity) { if(_collisionRecursionDepth > 5) return position; bool collisionFound = false; Vector2 futurePosition = position + velocity; Vector2 intersectionPoint = new Vector2(); Vector2 intersectionPointNormal = new Vector2(); /* I did not include the collision detection code, if a collision is detected the intersection point and normal in that point is returned. */ if(!collisionFound) return futurePosition; /* If no collision was detected it is safe to move to the future position. */ /* It is not exactly the intersection point, but slightly before. */ Vector2 newPosition = intersectionPoint; /* oldVelocity is set to the distance from the newPosition(intersection point) to the position it had moved to had it not collided. */ Vector2 oldVelocity = futurePosition - newPosition; /* Project the distance left to move along the intersection normal. */ Vector2 newVelocity = oldVelocity - intersectionPointNormal * oldVelocity.DotProduct(intersectionPointNormal); if(newVelocity.LengthSq() < 0.001) return newPosition; /* If almost no speed, no need to continue. */ _collisionRecursionDepth++; return SlidingCollision(newPosition, newVelocity); } What am I doing wrong with the velocity? I have been staring at this for very long so I have gone blind. I have tried different values of recursion depth but it does not seem to make it better. Let me know if you need more information. I appreciate any help. EDIT: A combination of Patrick Hughes' and teodron's answers solved the velocity problem (I think), thanks a lot! This is the new code: I decided to use a separate recursion method now too since I don't want to recalculate the acceleration in each recursion. public override void Update(double fixedTimeStep) { Acceleration.Zero();// = CalculateAcceleration(fixedTimeStep); PreviousState = new MovingEntityState(CurrentState.Position, CurrentState.Velocity); CurrentState = SlidingCollision(CurrentState, fixedTimeStep); Heading = Vector2.NormalizeRet(CurrentState.Velocity); } private MovingEntityState SlidingCollision(MovingEntityState state, double timeStep) { bool collisionFound = false; /* Calculate the next position given no detected collision. */ Vector2 futurePosition = state.Position + state.Velocity * timeStep; Vector2 intersectionPoint = new Vector2(); Vector2 intersectionPointNormal = new Vector2(); /* I did not include the collision detection code, if a collision is detected the intersection point and normal in that point is returned. */ /* If no collision was detected it is safe to move to the future position. */ if (!collisionFound) return new MovingEntityState(futurePosition, state.Velocity); /* Set new position to the intersection point (slightly before). */ Vector2 newPosition = intersectionPoint; /* Project the new velocity along the intersection normal. */ Vector2 newVelocity = state.Velocity - 1.90 * intersectionPointNormal * state.Velocity.DotProduct(intersectionPointNormal); /* Calculate the time of collision. */ double timeOfCollision = Math.Sqrt((newPosition - state.Position).LengthSq() / (futurePosition - state.Position).LengthSq()); /* Calculate new time step, remaining time of full step after the collision * current time step. */ double newTimeStep = timeStep * (1 - timeOfCollision); return SlidingCollision(new MovingEntityState(newPosition, newVelocity), newTimeStep); } Even though the code above seems to slide the puck correctly please have a look at it. I have a few questions, if I don't multiply by 1.90 in the newVelocity calculation it doesn't work (I get a stack overflow when the puck enters the corner because the timeStep decreases very slowly - a collision is found early in every recursion), why is that? what does 1.90 really do and why 1.90? Also I have a new problem, the puck does not move parallell to the short side after exiting the curve; to be more exact it moves outside the rink (I am not checking for any collisions with the short side at the moment). When I perform the collision detection I first check that the puck is in the correct quadrant. For example bottom-right corner is quadrant four i.e. circleCenter.X < puck.X && circleCenter.Y puck.Y is this a problem? or should the short side of the rink be the one to make the puck go parallell to it and not the last collision in the corner? EDIT2: This is the code I use for collision detection, maybe it has something to do with the fact that I can't make the puck slide (-1.0) but only reflect (-2.0): /* Point is the current position (not the predicted one) and quadrant is 4 for the bottom-right corner for example. */ if (GeometryHelper.PointInCircleQuadrant(circleCenter, circleRadius, state.Position, quadrant)) { /* The line is: from = state.Position, to = futurePosition. So a collision is detected when from is inside the circle and to is outside. */ if (GeometryHelper.LineCircleIntersection2d(state.Position, futurePosition, circleCenter, circleRadius, intersectionPoint, quadrant)) { collisionFound = true; /* Set the intersection point to slightly before the real intersection point (I read somewhere this was good to do because of floting point precision, not sure exactly how much though). */ intersectionPoint = intersectionPoint - Vector2.NormalizeRet(state.Velocity) * 0.001; /* Normal at the intersection point. */ intersectionPointNormal = Vector2.NormalizeRet(circleCenter - intersectionPoint) } } When I set the intersection point, if I for example use 0.1 instead of 0.001 the puck travels further before it gets stuck, but for all values I have tried (including 0 - the real intersection point) it gets stuck somewhere (but I necessarily not get a stack overflow). Can something in this part be the cause of my problem? I can see why I get the stack overflow when using -1.0 when calculating the new velocity vector; but not how to solve it. I traced the time steps used in the recursion (initial time step is always 1/60 ~ 0.01666): Recursion depth Time step next recursive call [Start recursion, time step ~ 0.016666] 0 0,000985806527246773 [No collision, stop recursion] [Start recursion, time step ~ 0.016666] 0 0,0149596704364629 1 0,0144883449376379 2 0,0143155612984837 3 0,014224925727213 4 0,0141673917461608 5 0,0141265435314026 6 0,0140953966184117 7 0,0140704653746625 ...and so on. As you can see the collision is detected early in every recursive call which means the next time step decreases very slowly thus the recursion depth gets very big - stack overflow.

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