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  • XNA Rendering vertices that only appear within the cameras view

    - by user1157885
    I'm making a game in XNA and I recall hearing that professionally made games use a technique to only render the polygons that appear within the cameras projection. I've been trying to find something on this to do something similar in my game, could anyone point me in the right direction? Right now all I have is a plane/grid of vertices that you can set the X/Y on which is drawn using DrawUserIndexedPrimitives, but I plan to make a bunch of props as scenery items and I can imagine myself running into issues later on if I don't address this now. Thanks

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  • bump mapping with 2 normal maps

    - by DorkMonstuh
    I was wondering if its actually possible to do bump mapping with 2 normal maps... I have tried doing it this way however I get a function overload on max and dot. uniform sampler2D n_mapTex; uniform sampler2D n_mapTex2; uniform sampler2D refTex; varying mediump vec2 TexCoord; varying mediump float vTime; void main() { mediump vec4 wave = texture2D(n_mapTex, TexCoord - vTime); mediump vec4 wave2 = texture2D(n_mapTex2, TexCoord + vTime); mediump vec4 bump = mix(wave2, wave, 0.5); //this extracts the normals from the combined normal maps mediump vec4 normal = normalize(bump.xyzw * 2.0 - 1.0); //determines light position mediump vec3 lightPos = normalize(vec3(0.0, 1.0, 3.0)); mediump float diffuse = max(dot(normal, lightPos),0.0); gl_FragColor = mix(texture2D(refTex, TexCoord), bump, 0.5); }

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  • Multithreading in lwjgl getting rid of sleep.

    - by pangaea
    I'm trying to use multithreading in my game. However, I can't seem to get rid of the sleep. If I don't it's a blank screen, as there is no time for the computer to actually render the triangleMob as it can't access getArrayList(), in my main class I have a TriangleMob arraylist. If I delay it, then it can access the previousMob and it renders. If I don't, then it's blank screen. Can I get rid of the delay? Also, is this a bad way to multithread? Surely, this should be fast. I need multithreading so can you please not suggest not using it. public class TriangleMob extends Thread implements Runnable { private static int count=0; private int objectDisplayList; private static ArrayList<TriangleMob> previousMob = new ArrayList<TriangleMob>(); private static ArrayList<TriangleMob> currentMob = new ArrayList<TriangleMob>(); private static ArrayList<TriangleMob> laterMob = new ArrayList<TriangleMob>(); private Vector3f position = new Vector3f(0f,0f,0f); private Vector3f movement = new Vector3f(0f,0f,0f); public TriangleMob() { // Create the display list CreateDisplayList(); count++; } public TriangleMob(Vector3f position) { // Create the display list CreateDisplayList(); this.position = position; count++; } private void CreateDisplayList() { objectDisplayList = glGenLists(1); glNewList(objectDisplayList, GL_COMPILE); { double topPoint = 0.75; glBegin(GL_TRIANGLES); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -0.75, -4); glColor4f(0, 0, 1, 1f); glVertex3d(1, -.75, -4); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -4); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -6); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -6); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -.75, -6); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -0.75, -6); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -.75, -4); glEnd(); glColor4f(1, 1, 1, 1); } glEndList(); } public static int getCount() { return count; } public Vector3f getMovement() { return movement; } public Vector3f getPosition() { return position; } public synchronized int getObjectList() { return objectDisplayList; } public synchronized static ArrayList<TriangleMob> getArrayList(){ if(previousMob != null) { return previousMob; } previousMob.add(new TriangleMob()); return previousMob; } public synchronized void move(Vector3f movement) { // If you want to move in all 3 axis position.x += movement.x; position.y += movement.y; position.z += movement.z; } public synchronized void render() { glPushMatrix(); glTranslatef(-position.x, -position.y, -position.z); glCallList(objectDisplayList); glPopMatrix(); } public synchronized static void setTriangleMob(ArrayList<TriangleMob> triangleMobSet) { laterMob = triangleMobSet; } private synchronized void setPreTriangleMob(ArrayList<TriangleMob> currentMob2) { previousMob = currentMob2; } public void run(){ while(true) { if(laterMob == null) { currentMob = laterMob; System.out.println("Copying"); } for(int i=0; i<currentMob.size(); i++) { currentMob.get(i).move(new Vector3f(0.1f,0.01f,0.01f)); } setPreTriangleMob(currentMob); try { sleep(1L); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }

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  • What is the best way to exploit multicores when making multithread games?

    - by Keeper
    Many people suggest to write a program, and then start optimizing it. But I think that when it's coming to multithreading with multicore, a little think ahead is required. I've read about using threads, and experienced it myself during some courses at the university (still a student). The big question is simple, but a bit abstract: What thread related steps in game design do I need to take, before implementation? Now trying to be more specific. Let's say, as an example, that I'm making a small board game (like Monopoly) that I want to be multithreaded. My goal Is that this multithreaded game will exploit the best of the multicore system, lets say 4-6 cores (like in i7 processors). My answer to this question at the moment is, one thread for each of these four basic components: GUI User Input / Output AI (computer rival) Other game related calculations (like shortest path from A to B, or level up status change) I'm not an expert (yet!), and I'm sure there are better answers out there. Any suggestion, answer, different approach will be helpful. Some thoughts: Maybe splitting the main database is a good way.. (or total disaster.. )

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  • Best system for creating a 2d racing track

    - by tesselode
    I am working a 2D racing game and I'm trying to figure out what is the best way to define the track. At the very least, I need to be able to create a closed circuit with any amount of turns at any angle, and I need vehicles to collide with the edges of the track. I also want the following things to be true if possible (but they are optional): The code is simple and free of funky workarounds and extras I can define all of the parts of the track (such as turns) relative to the previous parts I can predict the exact position of the road at a certain point (that way I can easily and cleanly make closed circuits) Here are my options: Use a set of points. This is my current system. I have a set of turns and width changes that the track is supposed to make over time. I have a point which I transform according to these instructions, and I place a point every 5 steps or so, depending on how precise I want the track to be. These points make up the track. The main problem with this is the discrepancy between the collisions and the way the track is drawn. I won't get into too much detail, but the picture below shows what is happening (although it is exaggerated a bit). The blue lines are what is drawn, the red lines are what the vehicle collides with. I could work around this, but I'd rather avoid funky workaround code. Beizer curves. These seem cool, but my first impression of them is that they'll be a little daunting to learn and are probably too complicated for my needs. Some other kind of curve? I have heard of some other kinds of curves; maybe those are more applicable. Use Box2D or another physics engine. Instead of defining the center of the track, I could use a physics engine to define shapes that make up the road. The downside to this, however, is that I have to put in a little more work to place the checkpoints. Something completely different. Basically, what is the simplest system for generating a race track that would allow me to create closed circuits cleanly, handle collisions, and not have a ton of weird code?

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  • Nice function for "rolling score up"?

    - by bobobobo
    I'm adding to the player's score, and I'm using a per-frame formula like: int score, displayedScore ;// score is ACTUAL score player has, // displayedScore is what is shown this frame to the player // (the creeping/"rolling" number) float disparity = score - displayedScore ; int d = disparity * .1f ; // add 1/10 of the difference, if( !d ) d = signum( disparity ) ; // last 10 go by 1's score += d ; Where inline int signum( float val ){ if( val > 0 ) return 1 ; else if( val < 0 ) return -1 ; else return 0 ; } So, it kind of works where it makes big changes rapidly, then it creeps in the last few one at a time. But I'm looking for better (or possibly well known?) score-creeping functions. Any one?

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  • What tools should I consider if my aim is to make a game available to as many platforms as possible?

    - by Kensai
    We're planning on developing a 2D, grid-based puzzle game, and although it's still very early in the planning stages, we'd like to make our decisions well from the beginning. Our strategy will be to make the game available to as many platforms as possible, for example PCs (Windows, Mac and/or Linux), mobile phones (iPhone and/or Android based phones), game consoles (XBLA and/or PSN) PC will have an emphasis, but I believe that's the most flexible platform so that shouldn't be a problem. So, what programming language, game engine, frameworks and all around tools would be best suited for our goal? P.S.: I'm betting a set of tools won't cover ALL of them, and that there will still be some kind of "translating" effort for some platforms, but we'd like to know what the most far reaching are.

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  • How to implement behavior in a component-based game architecture?

    - by ghostonline
    I am starting to implement player and enemy AI in a game, but I am confused about how to best implement this in a component-based game architecture. Say I have a following player character that can be stationary, running and swinging a sword. A player can transit to the swing sword state from both the stationary and running state, but then the swing must be completed before the player can resume standing or running around. During the swing, the player cannot walk around. As I see it, I have two implementation approaches: Create a single AI-component containing all player logic (either decoupled from the actual component or embedded as a PlayerAIComponent). I can easily how to enforce the state restrictions without creating coupling between individual components making up the player entity. However, the AI-component cannot be broken up. If I have, for example, an enemy that can only stand and walk around or only walks around and occasionally swing a sword, I have to create new AI-components. Break the behavior up in components, each identifying a specific state. I then get a StandComponent, WalkComponent and SwingComponent. To enforce the transition rules, I have to couple each component. SwingComponent must disable StandComponent and WalkComponent for the duration of the swing. When I have an enemy that only stands around, swinging a sword occasionally, I have to make sure SwingComponent only disables WalkComponent if it is present. Although this allows for better mix-and-matching components, it can lead to a maintainability nightmare as each time a dependency is added, the existing components must be updated to play nicely with the new requirements the dependency places on the character. The ideal situation would be that a designer can build new enemies/players by dragging components into a container, without having to touch a single line of engine or script code. Although I am not sure script coding can be avoided, I want to keep it as simple as possible. Summing it all up: Should I lob all AI logic into one component or break up each logic state into separate components to create entity variants more easily?

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  • Zooming to point of interest

    - by user1010005
    I have the following variables: Point of interest which is the position(x,y) in pixels of the place to focus. Screen width,height which are the dimensions of the window. Zoom level which sets the zoom level of the camera. And this is the code I have so far. void Zoom(int pointOfInterestX,int pointOfInterstY,int screenWidth, int screenHeight,int zoomLevel) { glTranslatef( (pointOfInterestX/2 - screenWidth/2), (pointOfInterestY/2 - screenHeight/2),0); glScalef(zoomLevel,zoomLevel,zoomLevel); } And I want to do zoom in/out but keep the point of interest in the middle of the screen. but so far all of my attempts have failed and I would like to ask for some help.

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  • Finding inspiration / help for making up (weapon) names

    - by Rookie
    I'm really bad with words, especially with English words. Currently I'm struggling to make a good weapon names for my game, it needs to display the weapon functionality (weak/strong/fast/ballistic etc) correctly as well. For example the best weapon in a (futuristic) game cannot be called just with the name "Laser", it's just too boring, right? Are there any tools, websites or anything that helps me finding good names for weapons? (or anything else similar). I was thinking to use scientific names, but noticed that they are really hard to write, and they get very long, and I also lack information about science, I only know I could use the atomic sub-particles names in the weapons for example. How do I get started with becoming good with making up names? (this could apply in generally to any naming problems).

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  • Box2D Difference Between WorldCenter and Position

    - by Free Lancer
    So this problem has been brothering for a couple of days now. First off, what is the difference between say Body.getWorldCenter() and Body.getPosition(). I heard that WorldCenter might have to do with the center of gravity or something. Second, When I create a Box2D Body for a sprite the Body is always at the lower left corner. I check it by printing a Rectangle of 1 pixel around the box.getWorldCenter(). From what I understand the Body should be in the center of the Sprite and its bounding box should wrap around the Sprite, correct? Here's an image of what I mean (The Sprite is Red, Body Blue): Here's some code: Body Creator: public static Body createBoxBody( final World pPhysicsWorld, final BodyType pBodyType, final FixtureDef pFixtureDef, Sprite pSprite ) { float pRotation = 0; float pCenterX = pSprite.getX() + pSprite.getWidth() / 2; float pCenterY = pSprite.getY() + pSprite.getHeight() / 2; float pWidth = pSprite.getWidth(); float pHeight = pSprite.getHeight(); final BodyDef boxBodyDef = new BodyDef(); boxBodyDef.type = pBodyType; //boxBodyDef.position.x = pCenterX / Constants.PIXEL_METER_RATIO; //boxBodyDef.position.y = pCenterY / Constants.PIXEL_METER_RATIO; boxBodyDef.position.x = pSprite.getX() / Constants.PIXEL_METER_RATIO; boxBodyDef.position.y = pSprite.getY() / Constants.PIXEL_METER_RATIO; Vector2 v = new Vector2( boxBodyDef.position.x * Constants.PIXEL_METER_RATIO, boxBodyDef.position.y * Constants.PIXEL_METER_RATIO ); Gdx.app.log("@Physics", "createBoxBody():: Box Position: " + v); // Temporary Box shape of the Body final PolygonShape boxPoly = new PolygonShape(); final float halfWidth = pWidth * 0.5f / Constants.PIXEL_METER_RATIO; final float halfHeight = pHeight * 0.5f / Constants.PIXEL_METER_RATIO; boxPoly.setAsBox( halfWidth, halfHeight ); // set the anchor point to be the center of the sprite pFixtureDef.shape = boxPoly; final Body boxBody = pPhysicsWorld.createBody(boxBodyDef); Gdx.app.log("@Physics", "createBoxBody():: Box Center: " + boxBody.getPosition().mul(Constants.PIXEL_METER_RATIO)); boxBody.createFixture(pFixtureDef); boxBody.setTransform( boxBody.getWorldCenter(), MathUtils.degreesToRadians * pRotation ); boxPoly.dispose(); return boxBody; } Making the Sprite: public Car( Texture texture, float pX, float pY, World world ) { super( "Car" ); mSprite = new Sprite( texture ); mSprite.setSize( mSprite.getWidth() / 6, mSprite.getHeight() / 6 ); mSprite.setPosition( pX, pY ); mSprite.setOrigin( mSprite.getWidth()/2, mSprite.getHeight()/2); FixtureDef carFixtureDef = new FixtureDef(); // Set the Fixture's properties, like friction, using the car's shape carFixtureDef.restitution = 1f; carFixtureDef.friction = 1f; carFixtureDef.density = 1f; // needed to rotate body using applyTorque mBody = Physics.createBoxBody( world, BodyDef.BodyType.DynamicBody, carFixtureDef, mSprite ); }

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  • Bukkit inventory saving: crashing somewhere

    - by HcgRandon
    I'm working on a command for a bukkit plugin that lets you transfer worlds. In the section about saving the player's inventory, I'm getting a runtime error. My question is: Why is the error happening, and how can I prevent it? The plugin code public void savePlayerInv(Player p, World w){ File playerInvConfigFile = new File(plugin.getDataFolder() + File.separator + "players" + File.separator + p.getName(), "inventory.yml"); FileConfiguration pInv = YamlConfiguration.loadConfiguration(playerInvConfigFile); PlayerInventory inv = p.getInventory(); int i = 0; for (ItemStack stack : inv.getContents()) { //increment integer i++; String startInventory = w.getName() + ".inv." + Integer.toString(i); //save inv pInv.set(startInventory + ".amount", stack.getAmount()); pInv.set(startInventory + ".durability", Short.toString(stack.getDurability())); pInv.set(startInventory + ".type", stack.getTypeId()); //pInv.set(startInventory + ".enchantment", stack.getEnchantments()); //TODO add enchant saveing } i = 0; for (ItemStack armor : inv.getArmorContents()){ i++; String startArmor = w.getName() + ".armor." + Integer.toString(i); //save armor pInv.set(startArmor + ".amount", armor.getAmount()); pInv.set(startArmor + ".durability", armor.getDurability()); pInv.set(startArmor + ".type", armor.getTypeId()); //pInv.set(startArmor + ".enchantment", armor.getEnchantments()); } //save exp if (p.getExp() != 0) { pInv.set(w.getName() + ".exp", p.getExp()); } } The offending line The stack trace complains about line 130, which is this line. pInv.set(startInventory + ".amount", stack.getAmount()); The stack trace 2012-03-21 13:23:25 [SEVERE] null org.bukkit.command.CommandException: Unhandled exception executing command 'wtp' in plugin Needs v1.0 at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42) at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:166) at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:461) at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:818) at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:778) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:761) at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33) at net.minecraft.server.NetworkManager.b(NetworkManager.java:229) at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:112) at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78) at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:554) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:452) at net.minecraft.server.ThreadServerApplication.run(SourceFile:490) Caused by: java.lang.NullPointerException at com.devoverflow.improved.needs.commands.CommandWorldtp.savePlayerInv(CommandWorldtp.java:130) at com.devoverflow.improved.needs.commands.CommandWorldtp.onCommand(CommandWorldtp.java:60) at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40) ... 12 more

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  • How can I render a semi transparent model with OpenGL correctly?

    - by phobitor
    I'm using OpenGL ES 2 and I want to render a simple model with some level of transparency. I'm just starting out with shaders, and I wrote a simple diffuse shader for the model without any issues but I don't know how to add transparency to it. I tried to set my fragment shader's output (gl_FragColor) to a non opaque alpha value but the results weren't too great. It sort of works, but it looks like certain model triangles are only rendered based on the camera position... It's really hard to describe what's wrong so please watch this short video I recorded: http://www.youtube.com/watch?v=s0JqA0rZabE I thought this was a depth testing issue so I tried playing around with enabling/disabling depth testing and back face culling. Enabling back face culling changes the output slightly but the problem in the video is still there. Enabling/disabling depth testing doesn't seem to do anything. Could anyone explain what I'm seeing and how I can add some simple transparency to my model with the shader? I'm not looking for advanced order independent transparency implementations. edit: Vertex Shader: // color varying for fragment shader varying mediump vec3 LightIntensity; varying highp vec3 VertexInModelSpace; void main() { // vec4 LightPosition = vec4(0.0, 0.0, 0.0, 1.0); vec3 LightColor = vec3(1.0, 1.0, 1.0); vec3 DiffuseColor = vec3(1.0, 0.25, 0.0); // find the vector from the given vertex to the light source vec4 vertexInWorldSpace = gl_ModelViewMatrix * vec4(gl_Vertex); vec3 normalInWorldSpace = normalize(gl_NormalMatrix * gl_Normal); vec3 lightDirn = normalize(vec3(LightPosition-vertexInWorldSpace)); // save vertexInWorldSpace VertexInModelSpace = vec3(gl_Vertex); // calculate light intensity LightIntensity = LightColor * DiffuseColor * max(dot(lightDirn,normalInWorldSpace),0.0); // calculate projected vertex position gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } Fragment Shader: // varying to define color varying vec3 LightIntensity; varying vec3 VertexInModelSpace; void main() { gl_FragColor = vec4(LightIntensity,0.5); }

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  • SpriteBatch.Begin() making my model not render correctly

    - by manning18
    I was trying to output some debug information using DrawString when I noticed my model suddenly was being rendered like it was inside-out (like the culling had been disabled or something) and the texture maps weren't applied I commented out the DrawString method until I only had SpriteBatch.Begin() and .End() and that was enough to cause the model rendering corruption - when I commented those calls out the model rendered correctly What could this be a symptom of? I've stripped it down to the barest of code to isolate the problem and this is what I noticed. Draw code below (as stripped down as possible) GraphicsDevice.Clear(Color.LightGray); foreach (ModelMesh mesh in TIEAdvanced.Meshes) { foreach (Effect effect in mesh.Effects) { if (effect is BasicEffect) ((BasicEffect)effect).EnableDefaultLighting(); effect.CurrentTechnique.Passes[0].Apply(); } } spriteBatch.Begin(); spriteBatch.DrawString(spriteFont, "Camera Position: " + cameraPosition.ToString(), new Vector2(10, 10), Color.Blue); spriteBatch.End(); GraphicsDevice.DepthStencilState = DepthStencilState.Default; TIEAdvanced.Draw(Matrix.CreateScale(0.025f), viewMatrix, projectionMatrix);

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  • Draw contour around object in Opengl

    - by Maciekp
    I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green): http://goo.gl/OI5uc (sorry I can't post images, due to my reputation) You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object: glColorMask(1,1,1,1); std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end(); int countStencilBit=1; while(objIter!=objEnd) { glColorMask(1,1,1,1); glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit); glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE ); (*objIter)->DrawYourVertices(); glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit); glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE); (*objIter)->DrawYourBorder(); ++objIter; ++countStencilBit; } I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong? 2. Are there any other simple ways to create contour on such objects? Thanks in advance.

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  • what knowledge would I need to make a good simulation games

    - by Skeith
    I have an idea for a game like theme park but don't know how simulation games are made. I am not some noob on his first game so I appreciated constructive answers instead of "its hard, don't do it". What I want is to know how simulation game mechanics are put together. I figure it would be heaver on the AI than normal games and not knowing much about AI would like to know some programming techniques I should look into for this style game. specific techniques please not just a book on ai. what sort of architecture would be used? I guess it would have some sort of probability engine with pre designed events that are triggered based on the AI state. Would it use a FSM or be purely event driven ? Any information on how a sims game functions would be cool.

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  • Is it safe to set FPS rate to a constant?

    - by Ozan
    I learned from game class that in update function, every movements must be time dependent for the sake of linearity in movement. We made a simple game. Every move like going left, right or jump is written time dependent. But, in some other computers, our game is worked very differently. For example, our character jumps higher than it should be. I guess this is because each computer has different FPS rate according to its specification. My question is that what should we do to make this game work in same way in every computer? Setting FPS rate to a constant is a solution?

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  • Converting Degrees to X and Y Coordinate change

    - by gopgop
    I am using a float positioning system in my game. IE float x,y,z now I want to get the location of the mouse, then to fire an arrow to it. X0 = the players X location X1 = the mouse X location Y0 = the players Y location Y1 = the mouse Y location I want to make a method that the parameters are Degrees and it sets my Yspeed and my Xspeed accordingly to get to the mouse xy starting at player xy How do would I accomplish this?

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  • HTML5 Canvas Converting between cartesian and isometric coordinates

    - by Amir
    I'm having issues wrapping my head around the Cartesian to Isometric coordinate conversion in HTML5 canvas. As I understand it, the process is two fold: (1) Scale down the y-axis by 0.5, i.e. ctx.scale(1,0.5); or ctx.setTransform(1,0,0,0.5,0,0); This supposedly produces the following matrix: [x; y] x [1, 0; 0, 0.5] (2) Rotate the context by 45 degrees, i.e. ctx.rotate(Math.PI/4); This should produce the following matrix: [x; y] x [cos(45), -sin(45); sin(45), cos(45)] This (somehow) results in the final matrix of ctx.setTransform(2,-1,1,0.5,0,0); which I cannot seem to understand... How is this matrix derived? I cannot seem to produce this matrix by multiplying the scaling and rotation matrices produced earlier... Also, if I write out the equation for the final transformation matrix, I get: newX = 2x + y newY = -x + y/2 But this doesn't seem to be correct. For example, the following code draws an isometric tile at cartesian coordinates (500, 100). ctx.setTransform(2,-1,1,0.5,0,0); ctx.fillRect(500, 100, width*2, height); When I check the result on the screen, the actual coordinates are (285, 215) which do not satisfy the equations I produced earlier... So what is going on here? I would be very grateful if you could: (1) Help me understand how the final isometric transformation matrix is derived; (2) Help me produce the correct equation for finding the on-screen coordinates of an isometric projection. Many thanks and kind regards

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  • sdl stencil buffer

    - by noddy
    I am trying to use the stencil buffer for rendering reflection and am working with SDL and OpenGL. When I give the command SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE,8),I get a return value of 0 indicating success,but when I try to get the size allocated using SDL_GL_GetAtribute( SDL_GL_STENCIL_SIZE,&i),I get a value of 0 for my stencil buffer due to which I am not getting the desired rendering. Can someone help me to correct my mistake? Is there some other initialization also required? Thanks

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  • What are the steps taken by this GLSL code?

    - by user827992
    1 void main(void) 2 { 3 vec2 pos = mod(gl_FragCoord.xy, vec2(50.0)) - vec2(25.0); 4 float dist_squared = dot(pos, pos); 5 6 gl_FragColor = (dist_squared < 400.0) 7 ? vec4(.90, .90, .90, 1.0) 8 : vec4(.20, .20, .40, 1.0); 9 } taken from http://people.freedesktop.org/~idr/OpenGL_tutorials/03-fragment-intro.html Now, this looks really trivial and simple, but my problem is with the mod function. This function is taking 2 vec2 as inputs but is supposed to take just 2 atomic arguments according to the official documentation, also this function makes an implicit use of the floor function that only accepts, again, 1 atomic argument. Can someone explain this to me step by step and point out what I'm not getting here? It's some kind of OpenGL trick? OpenGL Math trick? in the GLSL docs i always find and explicit reference to the type accepted by the function and vec2 it's not there.

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  • How to achieve selection of a tile from a tile sheet based on an ID?

    - by Bugster
    Let's say I have a tile sheet that contains 8 sprites per sheet. Each sprite is a tile of 30x30. I wrote my own custom map parser/map loader however I'm having trouble extracting a certain tile sprite from the file. I'll describe my problem better in order for everyone to understand. I wrote an enum of materials, each material has a value according to it's location relative to the tile sheet. For example void is 1, grass is 2, rock is 3, etc. So in my tile sheet they are represented as such: +---+---+---+---+---+ | 1 | 2 | 3 | 4 | 5 | +---+---+---+---+---+ Which is equivalent to: +------+-------+-------+ | void | grass | stone | +------+-------+-------+ Basically when rendering, I created a tile class, each tile has 2 coordinates: X and Y (They are calculated automatically) and a material which can be represented either as a number, either as a value (ID). When rendering, I have a vector of sprites which are all taken from 1 file called tilesheet.png, however each of them must only draw a certain portion of the tile sheet, for example say I have something like this: tile coordinateBounds(topLeftX, topLeftY, tileWidth, tileHeight); During the initialization of the map I calculate an array of tiles, and I give each of them their position, their materials based on the values in a map file and a few other variables such as collision. I need to apply the coordinateBounds to each of them according to their material value. For example if the material is grass it should only take the grass sprite from the tilesheet. I must also mention I'm using SFML, and there are no borders or spacing between the tiles.

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  • Mouse Speed in GLUT and OpenGL?

    - by CroCo
    I would like to simulate a point that moves in 2D. The input should be the speed of the mouse, so the new position will be computed as following new_position = old_position + delta_time*mouse_velocity As far as I know in GLUT there is no function to acquire the current speed of the mouse between each frame. What I've done so far to compute the delta_time as following void Display() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glColor3f(1.0f, 0.0f, 0.0f); static int delta_t, current_t, previous_t; current_t = glutGet(GLUT_ELAPSED_TIME); delta_t = current_t - previous_t; std::cout << delta_t << std::endl; previous_t = current_t; glutSwapBuffers(); } Where should I start from here? (Note: I have to get the speed of the mouse because I'm modeling a system) Edit: Based on the above code, delta_time fluctuates so much 34 19 2 20 1 20 0 16 1 1 10 21 0 13 1 19 34 0 13 0 6 1 14 Why does this happen?

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  • How should I choose quadtree depth?

    - by Evpok
    I'm using a quadtree to prune collision detection pairs in a 2d world. How should I choose to what depth said quadtree is calculated? The world is made mostly of moving objects1, so the cost of dispatching the objects between the quadtree cells matters. What is the relationship between the gain from less collision checking and the loss from more dispatching? How can I strike a balance that performs optimally? 1 To be completely explicit, they are autonomous self-replicating cells competing for food sources. This is an attempt to show my pupils predator-prey dynamics and genetic evolution at work.

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  • How to sync client and server at the first frame

    - by wheelinlight
    I'm making a game where an authoritative server sends information to all clients about states and positions for objects in a 3d world. The player can control his character by clicking on the screen to set a destination for the character, much like in the Diablo series. I've read most information I can find online about interpolation, reconciliation, and general networking architecture (Valve's for instance). I think I understand everything but one thing seems to be missing in every article I read. Let say we have an interpolation delay of 100ms, server tickrate=50ms, latency=200ms; How do I know when 100ms has past on the client? If the server sends the first update on t=0, can I assume it arrives at t=200, therefore assuming that all packets takes the same amount of time to reach the client? What if the first packet arrives a little quick, for instance at t=150. I would then be starting the client with t=150 and at t=250 it will think it has past 100ms since its connect to the server when it in fact only 50ms has past. Hopefully the above paragraph is understandable. The summarized question would be: How do I know at what tick to start simulating the client? EDIT: This is how I ended up doing it: The client keeps a clock (approximately) in sync with the server. The client then simulates the world at simulationTime = syncedTime - avg(RTT)/2 - interpolationTime The round-trip time can fluctuate so therefore I average it out over time. By only keeping the most recent values when calculating the average I hope to adapt to more permanent changes in latency. It's still to early to draw any conclusion. I'm currently simulating bad network connections, but it's looking good so far. Anyone see any possible problems?

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