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• What library should I use for 2D Geometry? [closed]

  - by Luka

  I've been working on a 2D game in java, but found that java just didn't cut it for me and had forced me to a lot of bad design choices, so I've decided to port all my work to c++. The main reason I've decided change to c++ is that i had reached a point where i had 3 geometry libraries (the native, one from the game engine and one to handle "complex" polygons), none of witch worked very well together and i couldn't keep track of them. I'm new to c++, but i know all the basics. My question is, what would be a good geometry library to use, ideally it should be able to handle integer and decimal data types, have point, line, and polygon classes witch are able to check for intersection and contains. Thanks in advance, Luka

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• Generating and rendering not point-like particles on GPU

  - by TravisG

  Specifically I'm talking about particles as seen (for example) in the UE4 dev video here. They're not just points and seem to have a nice shape to them that seems to follow their movement. Is it possible to create these kinds of particles (efficiently) completely on the GPU (perhaps through something like motion? Or is the only (or most efficient) way to just create a small particle texture and render small quads for each particle?

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• How do I optimize searching for the nearest point?

  - by Rootosaurus

  For a little project of mine I'm trying to implement a space colonization algorithm in order to grow trees. The current implementation of this algorithm works fine. But I have to optimize the whole thing in order to make it generate faster. I work with 1 to 300K of random attraction points to generate one tree, and it takes a lot of time to compute and compare distances between attraction points and tree node in order to keep only the closest treenode for an attraction point. So I was wondering if some solutions exist (I know they must exist) in order to avoid the time loss looping on each tree node for each attraction point to find the closest... and so on until the tree is finished.

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• specifying an object type at runtime

  - by lapin

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

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• How do I make a simple level system?

  - by ROROX

  I've been learning programming for a while and things are slow but steady. I only have a couple experiments that look something like a game (JavaScript,HTML5,CANVAS). One of the things I would like to establish this early in my process though is a basic level system to my games. I'm thinking like Atari, NES type simple. mainMenu , level1 , level2 , ... Later I'll work on including such screens as; titleScreen , pause , highScore. But for now just looking for the basics. Any good articles/tutorial links would help. Or just a snippet of code I can look over. Thank you kindly :)

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• How to set sprite source coordinates?

  - by ChaosDev

  I am creating own sprite drawer with DX11 on C++. Works fine but I dont know how to apply source rectangle to texture coordinates of rendering surface(for animation sprite sheets) //source = (0,0,32,64); //RECT D3DXVECTOR2 t0 = D3DXVECTOR2( 1.0f, 0.0f); D3DXVECTOR2 t1 = D3DXVECTOR2( 1.0f, 1.0f); D3DXVECTOR2 t2 = D3DXVECTOR2( 0.0f, 1.0f); D3DXVECTOR2 t3 = D3DXVECTOR2( 0.0f, 1.0f); D3DXVECTOR2 t4 = D3DXVECTOR2( 0.0f, 0.0f); D3DXVECTOR2 t5 = D3DXVECTOR2( 1.0f, 0.0f); VertexPositionColorTexture vertices[] = { { D3DXVECTOR3( dest.left+dest.right, dest.top, z),D3DXVECTOR4(1,1,1,1), t0}, { D3DXVECTOR3( dest.left+dest.right, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t1}, { D3DXVECTOR3( dest.left, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t2}, { D3DXVECTOR3( dest.left, dest.top+dest.bottom, z),D3DXVECTOR4(1,1,1,1), t3}, { D3DXVECTOR3( dest.left , dest.top, z),D3DXVECTOR4(1,1,1,1), t4}, { D3DXVECTOR3( dest.left+dest.right, dest.top, z),D3DXVECTOR4(1,1,1,1), t5}, };

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

  - by Brandon

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

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• BoundingBox Intersection Problems

  - by Deukalion

  When I try to render two cubes, same sizes, one beside the other. With the same proportions (XYZ). My problem is, why do a Box1.BoundingBox.Contains(Box2.BoundingBox) == ContaintmentType.Intersects - when it clearly doesn't? I'm trying to place objects with BoundingBoxes as "intersection" checking, but this simple example clearly shows that this doesn't work. Why is that? I also try checking height of the next object to be placed, by checking intersection, adding each boxes height += (Max.Y - Min.Y) to a Height value, so when I add a new Box it has a height value. This works, but sometimes due to strange behavior it adds extra values when there isn't anything there. This is an example of what I mean: BoundingBox box1 = GetBoundaries(new Vector3(0, 0, 0), new Vector3(128, 64, 128)); BoundingBox box2 = GetBoundaries(new Vector3(128, 0, 0), new Vector3(128, 64, 128)); if (box1.Contains(box2) == ContainmentType.Intersects) { // This will be executed System.Windows.Forms.MessageBox.Show("Intersects = True"); } if (box1.Contains(box2) == ContainmentType.Disjoint) { System.Windows.Forms.MessageBox.Show("Disjoint = True"); } if (box1.Contains(box2) == ContainmentType.Contains) { System.Windows.Forms.MessageBox.Show("Contains = True"); } Test Method: public BoundingBox GetBoundaries(Vector3 position, Vector3 size) { Vector3[] vertices = new Vector3[8]; vertices[0] = position + new Vector3(-0.5f, 0.5f, -0.5f) * size; vertices[1] = position + new Vector3(-0.5f, 0.5f, 0.5f) * size; vertices[2] = position + new Vector3(0.5f, 0.5f, -0.5f) * size; vertices[3] = position + new Vector3(0.5f, 0.5f, 0.5f) * size; vertices[4] = position + new Vector3(-0.5f, -0.5f, -0.5f) * size; vertices[5] = position + new Vector3(-0.5f, -0.5f, 0.5f) * size; vertices[6] = position + new Vector3(0.5f, -0.5f, -0.5f) * size; vertices[7] = position + new Vector3(0.5f, -0.5f, 0.5f) * size; return BoundingBox.CreateFromPoints(vertices); } Box 1 should start at x -64, Box 2 should start at x 64 which means they never overlap. If I add Box 2 to 129 instead it creates a small gap between the cubes which is not pretty. So, the question is how can I place two cubes beside eachother and make them understand that they do not overlap or actually intersect? Because this way I can never automatically check for intersections or place cube beside eachother.

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

  - by Aidiakapi

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

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• correct pattern to handle a lot of entities in a game

  - by lezebulon

  In my game I usually have every NPC / items etc being derived from a base class "entity". Then they all basically have a virtual method called "update" that I would class for each entity in my game at every frame. I am assuming that this is a pattern that has a lot of downsides. What are some other ways to manage different "game objects" throughout the game? Are there other well-known patterns for this? My game is a RPG if that changes anything

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• Realistic Jumping

  - by Seth Taddiken

  I want to make the jumping that my character does more realistic. This is what I've tried so far but it doesn't seem very realistic when the player jumps. I want it to jump up at a certain speed then slow down as it gets to the top then eventually stopping (for about one frame) and then slowly going back down but going faster and faster as it goes back down. I've been trying to make the speed at which the player jumps up slow down by one each frame then become negative and go down faster... but it doesn't work very well public bool isPlayerDown = true; public bool maxJumpLimit = false; public bool gravityReality = false; public bool leftWall = false; public bool rightWall = false; public float x = 76f; public float y = 405f; if (Keyboard.GetState().IsKeyDown(up) && this.isPlayerDown == true && this.y <= 405f) { this.isPlayerDown = false; } if (this.isPlayerDown == false && this.maxJumpLimit == false) { this.y = this.y - 6; } if (this.y <= 200) { this.maxJumpLimit = true; } if (this.isPlayerDown == true) { this.y = 405f; this.isPlayerDown = true; this.maxJumpLimit = false; } if (this.gravityReality == true) { this.y = this.y + 2f; this.gravityReality = false; } if (this.maxJumpLimit == true) { this.y = this.y + 2f; this.gravityReality = true; } if (this.y > 405f) { this.isPlayerDown = true; }

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• Prevent collisions between mobs/npcs/units piloted by computer AI : How to avoid mobile obstacles?

  - by Arthur Wulf White

  Lets says we have character a starting at point A and character b starting at point B. character a is headed to point B and character b is headed to point A. There are several simple ways to find the path(I will be using Dijkstra). The question is, how do I take preventative action in the code to stop the two from colliding with one another? case2: Characters a and b start from the same point in different times. Character b starts later and is the faster of the two. How do I make character b walk around character a without going through it? case3:Lets say we have m such characters in each side and there is sufficient room to pass through without the characters overlapping with one another. How do I stop the two groups of characters from "walking on top of one another" and allow them pass around one another in a natural organic way. A correct answer would be any algorithm, that given the path to the destination and a list of mobile objects that block the path, finds an alternative path or stops without stopping all units when there is sufficient room to traverse.

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• AI agents with FSM: a question regarding this

  - by Prog

  Finite State Machines implemented with the State design pattern are a common way to design AI agents. I am familiar with the State design pattern and know how to implement it. However I have a question regarding how this is used in games to design AI agents. Please consider a class Monster that represents an AI agent. Simplified it looks like this: class Monster{ State state; // other fields omitted public void update(){ // called every game-loop cycle state.execute(this); } public void setState(State state){ this.state = state; } // irrelevant stuff omitted } There are several State subclasses that implement execute() differently. So far classic State pattern. Here's my question: AI agents are subject to environmental effects and other objects communicating with them. For example an AI agent might tell another AI agent to attack (i.e. agent.attack()). Or a fireball might tell an AI agent to fall down. This means that the agent must have methods such as attack() and fallDown(), or commonly some message receiving mechanism to understand such messages. My question is divided to two parts: 1- Please say if this is correct: With an FSM, the current State of the agent should be the one taking care of such method calls - i.e. the agent delegates to the current state upon every event. Correct? Or wrong? 2- If correct, than how is this done? Are all states obligated by their superclass) to implement methods such as attack(), fallDown() etc., so the agent can always delegate to them on almost every event? Or is it done in some other way?

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• How do I interpolate air drag with a variable time step?

  - by Valentin Krummenacher

  So I have a little game which works with small steps, however those steps vary in time, so for example I sometimes have 10 Steps/second and then I have 20 Steps/second. This changes automatically depending on how many steps the user's computer can take. To avoid inaccurate positioning of the game's player object I use y=v0*dt+g*dt^2/2 to determine my objects y-position, where dt is the time since the last step, v0 is the velocity of my object in the beginning of my step and g is the gravity. To calculate the velocity in the end of a step I use v=v0+g*dt what also gives me correct results, independent of whether I use 2 steps with a dt of for example 20ms or one step with a dt of 40ms. Now I would like to introduce air drag. For simplicity's sake I use a=k*v^2 where a is the air drag's acceleration (I am aware that it would usually result in a force, but since I assume 1kg for my object's mass the force is the same as the resulting acceleration), k is a constant (in this case I'm using 0.001) and v is the speed. Now in an infinitely small time interval a is k multiplied by the velocity in this small time interval powered by 2. The problem is that v in the next time interval would depend on the drag of the last which again depends on the v of the last interval and so on... In other words: If I use a=k*v^2 I get different results for my position/velocity when I use 2 steps of 20ms than when I use one step of 40ms. I used to have this problem for my position too, but adding +g*dt^2/2 to the formula for my position fixed the problem since it takes into account that the position depends on the velocity which changes slightly in every infinitely small time interval. Does something like that exist for air drag too? And no, I dont mean anything like Adding air drag to a golf ball trajectory equation or similar, for that kind of method only gives correct results when all my steps are the same. (I hope you can understand my intermediate english, it's not my main language so I would like to say sorry for all the silly mistakes I might have made in my question)

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• GLSL per pixel lighting with custom light type

  - by Justin

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

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• Glm Vector Transformations [duplicate]

  - by Reanimation

  This question already has an answer here: Car-like Physics - Basic Maths to Simulate Steering 2 answers I have a cube rendered on the screen which represents a car (or similar). Using Projection/Model matrices and Glm I am able to move it back and fourth along the axes and rotate it left or right. I'm having trouble with the vector mathematics to make the cube move forwards no matter which direction it's current orientation is. (ie. if I would like, if it's rotated right 30degrees, when it's move forwards, it travels along the 30degree angle on a new axes). I hope I've explained that correctly. This is what I've managed to do so far in terms of using glm to move the cube: glm::vec3 vel; //velocity vector void renderMovingCube(){ glUseProgram(movingCubeShader.handle()); GLuint matrixLoc4MovingCube = glGetUniformLocation(movingCubeShader.handle(), "ProjectionMatrix"); glUniformMatrix4fv(matrixLoc4MovingCube, 1, GL_FALSE, &ProjectionMatrix[0][0]); glm::mat4 viewMatrixMovingCube; viewMatrixMovingCube = glm::lookAt(camOrigin, camLookingAt, camNormalXYZ); vel.x = cos(rotX); vel.y=sin(rotX); vel*=moveCube; //move cube ModelViewMatrix = glm::translate(viewMatrixMovingCube,globalPos*vel); //bring ground and cube to bottom of screen ModelViewMatrix = glm::translate(ModelViewMatrix, glm::vec3(0,-48,0)); ModelViewMatrix = glm::rotate(ModelViewMatrix, rotX, glm::vec3(0,1,0)); //manually turn glUniformMatrix4fv(glGetUniformLocation(movingCubeShader.handle(), "ModelViewMatrix"), 1, GL_FALSE, &ModelViewMatrix[0][0]); //pass matrix to shader movingCube.render(); //draw glUseProgram(0); } keyboard input: void keyboard() { char BACKWARD = keys['S']; char FORWARD = keys['W']; char ROT_LEFT = keys['A']; char ROT_RIGHT = keys['D']; if (FORWARD) //W - move forwards { globalPos += vel; //globalPos.z -= moveCube; BACKWARD = false; } if (BACKWARD)//S - move backwards { globalPos.z += moveCube; FORWARD = false; } if (ROT_LEFT)//A - turn left { rotX +=0.01f; ROT_LEFT = false; } if (ROT_RIGHT)//D - turn right { rotX -=0.01f; ROT_RIGHT = false; } Where am I going wrong with my vectors? I would like change the direction of the cube (which it does) but then move forwards in that direction.

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• Inputting cheat codes - hidden keyboard input

  - by Fibericon

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

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• LWJGL GL_QUADS texture artifact

  - by Dajgoro Labinac

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

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• XNA 4: RenderTarget2D textures getting transparent on fullscreen

  - by Shashwat

  I'm generating a Texture2D object using RenderTarget2D as in the following code public static Texture2D GetTextTexture(string text, Vector2 position, SpriteFont font, Color foreColor, Color backColor, Texture2D background=null) { int width = (int)font.MeasureString(text).X; int height = (int)font.MeasureString(text).Y; GraphicsDevice device = Settings.game.GraphicsDevice; SpriteBatch spriteBatch = Settings.game.spriteBatch; RenderTarget2D renderTarget = new RenderTarget2D(device, width, height, false, SurfaceFormat.Color, DepthFormat.Depth24Stencil8, device.PresentationParameters.MultiSampleCount, RenderTargetUsage.DiscardContents); device.SetRenderTarget(renderTarget); device.Clear(backColor); spriteBatch.Begin(SpriteSortMode.Immediate, BlendState.Opaque); if (background != null) spriteBatch.Draw(background, new Rectangle(0, 0, 70, 70), Color.White); spriteBatch.End(); spriteBatch.Begin(); spriteBatch.DrawString(font, text, position, foreColor, 0, new Vector2(0), 0.8f, SpriteEffects.None, 0); spriteBatch.End(); device.SetRenderTarget(null); ResetGraphicsDeviceSettings(); return (Texture2D)renderTarget; } It's working all fine. But when I ToggleFullScreen() (and vice-versa), the previous textures are getting transparent. However, the new textures after that are being generated correctly. What can be the reason for this?

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• How can I imitate interaction and movement in Diablo II?

  - by user422318

  I'm prototyping a simple browser-based game. It's played from a top down perspective on a 2d canvas. You left-click on a point on the map, and your character will begin walking to it. If you click on a different point on the map, then your character will begin walking to the new point. It's similar to Diablo II: http://www.youtube.com/watch?v=EvDKt-To6K0&feature=related How can I best imitate this movement system for a player? Ideas... Track current coords and target coords If target coords are exactly up, left, right, or down, then increment appropriate direction until you get there Implied else: target coords are in a quadrant. To make this movement look natural, character will have to move diagonally. For example, pretend the target is to the northeast. For each game frame, alternate incrementing current coordinates in the north and then east directions.

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• Problem with Update(GameTime) Methods and Pause implementation

  - by Adam

  I have the pause function implemented and it works correctly in that it dims the player screen and stops updating the gameplay. The problem is that GameTime continues to increase while it is paused, so my method that checks gameTime versus previousSpawnTime before spawning another enemy gets messed up and if the game is paused too long it is noticeable that the next enemy draws far too early. Here is my code for the enemy update. private void UpdateEnemies(GameTime gameTime) { // Spawn a new enemy every 1.5 seconds if (gameTime.TotalGameTime - previousSpawnTime > enemySpawnTime) { previousSpawnTime = gameTime.TotalGameTime; // Add an Enemy AddEnemy(); } ... I also have other methods that depend on gameTime. I've tried getting the total pause time and subtracting that from the total game time, but I can't seem to get it to work correctly if that is the way I should go about solving this. If you need to see any other code let me know. Thank you.

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• What are the semantics of glRotate and glTranslate's parameters?

  - by Zarkopafilis

  I have been trying to play with OpenGL after watching some tutorials and I don't understand how the glTranslatef and glRotatef functions work. I believe a simple picture would help me. I understand that glTranslatef changes the position of the "camera" (but does it change the position in wich the shapes are getting drawn)? However, I don't understand the rotation concept at all. If I do glRotatef(1,0,0,1) it makes my quad spin around. If I just do glRotatef(1,0,0,0) it makes the quad smaller (further away) but if I try to rotate around the X or Y axis, I get a black screen. I don't understand the angle either. Help would be appreciated.

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• infer half vector length in BRDF

  - by cician

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

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• Accounting for waves when doing planar reflections

  - by CloseReflector

  I've been studying Nvidia's examples from the SDK, in particular the Island11 project and I've found something curious about a piece of HLSL code which corrects the reflections up and down depending on the state of the wave's height. Naturally, after examining the brief paragraph of code: // calculating correction that shifts reflection up/down according to water wave Y position float4 projected_waveheight = mul(float4(input.positionWS.x,input.positionWS.y,input.positionWS.z,1),g_ModelViewProjectionMatrix); float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; projected_waveheight = mul(float4(input.positionWS.x,-0.8,input.positionWS.z,1),g_ModelViewProjectionMatrix); waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; reflection_disturbance.y=max(-0.15,waveheight_correction+reflection_disturbance.y); My first guess was that it compensates for the planar reflection when it is subjected to vertical perturbation (the waves), shifting the reflected geometry to a point where is nothing and the water is just rendered as if there is nothing there or just the sky: Now, that's the sky reflecting where we should see the terrain's green/grey/yellowish reflection lerped with the water's baseline. My problem is now that I cannot really pinpoint what is the logic behind it. Projecting the actual world space position of a point of the wave/water geometry and then multiplying by -.5f, only to take another projection of the same point, this time with its y coordinate changed to -0.8 (why -0.8?). Clues in the code seem to indicate it was derived with trial and error because there is redundancy. For example, the author takes the negative half of the projected y coordinate (after the w divide): float waveheight_correction=-0.5*projected_waveheight.y/projected_waveheight.w; And then does the same for the second point (only positive, to get a difference of some sort, I presume) and combines them: waveheight_correction+=0.5*projected_waveheight.y/projected_waveheight.w; By removing the divide by 2, I see no difference in quality improvement (if someone cares to correct me, please do). The crux of it seems to be the difference in the projected y, why is that? This redundancy and the seemingly arbitrary selection of -.8f and -0.15f lead me to conclude that this might be a combination of heuristics/guess work. Is there a logical underpinning to this or is it just a desperate hack? Here is an exaggeration of the initial problem which the code fragment fixes, observe on the lowest tessellation level. Hopefully, it might spark an idea I'm missing. The -.8f might be a reference height from which to deduce how much to disturb the texture coordinate sampling the planarly reflected geometry render and -.15f might be the lower bound, a security measure.

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• How can I cleanly and elegantly handle data and dependancies between classes

  - by Neophyte

  I'm working on 2d topdown game in SFML 2, and need to find an elegant way in which everything will work and fit together. Allow me to explain. I have a number of classes that inherit from an abstract base that provides a draw method and an update method to all the classes. In the game loop, I call update and then draw on each class, I imagine this is a pretty common approach. I have classes for tiles, collisions, the player and a resource manager that contains all the tiles/images/textures. Due to the way input works in SFML I decided to have each class handle input (if required) in its update call. Up until now I have been passing in dependencies as needed, for example, in the player class when a movement key is pressed, I call a method on the collision class to check if the position the player wants to move to will be a collision, and only move the player if there is no collision. This works fine for the most part, but I believe it can be done better, I'm just not sure how. I now have more complex things I need to implement, eg: a player is able to walk up to an object on the ground, press a key to pick it up/loot it and it will then show up in inventory. This means that a few things need to happen: Check if the player is in range of a lootable item on keypress, else do not proceed. Find the item. Update the sprite texture on the item from its default texture to a "looted" texture. Update the collision for the item: it might have changed shape or been removed completely. Inventory needs to be updated with the added item. How do I make everything communicate? With my current system I will end up with my classes going out of scope, and method calls to each other all over the place. I could tie up all the classes in one big manager and give each one a reference to the parent manager class, but this seems only slightly better. Any help/advice would be greatly appreciated! If anything is unclear, I'm happy to expand on things.

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