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  • Space-efficient data structures for broad-phase collision detection

    - by Marian Ivanov
    As far as I know, these are three types of data structures that can be used for collision detection broadphase: Unsorted arrays: Check every object againist every object - O(n^2) time; O(log n) space. It's so slow, it's useless if n isn't really small. for (i=1;i<objects;i++){ for(j=0;j<i;j++) narrowPhase(i,j); }; Sorted arrays: Sort the objects, so that you get O(n^(2-1/k)) for k dimensions O(n^1.5) for 2d and O(n^1.67) for 3d and O(n) space. Assuming the space is 2D and sortedArray is sorted so that if the object begins in sortedArray[i] and another object ends at sortedArray[i-1]; they don't collide Heaps of stacks: Divide the objects between a heap of stacks, so that you only have to check the bucket, its children and its parents - O(n log n) time, but O(n^2) space. This is probably the most frequently used approach. Is there a way of having O(n log n) time with less space? When is it more efficient to use sorted arrays over heaps and vice versa?

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  • How to give a ball a following texture trailing effect

    - by Evan Kohilas
    How do I draw copies of the leading texture so that there is a line of the leading ball following behind it? (that don't collide) So far I have tried to create the effect by placing another graphic 2 pixels off the graphic, but I don't see the second ball being drawn. spriteBatch.Draw(ballTexture, ballPos, null, Color.White, 0.0f, new Vector2(Ballpos.X +2, ballPos.Y +2), ballSize, SpriteEffects.None, 0); Thanks.

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  • How to keep balance / Unlock items / achievement rules

    - by Mark Knol
    I'm working on an engine for a game, too learn javascript and just because its fun. I'm a flashdeveloper, I know how to build websites. Now making games is a different challenge, javascript is a challenge, but I'd love to learn how to structure code and what patterns are common. I dont mind if the game ever finish, I'm mostly interested in the programming part of it. I dont have a particular endresult in mind, so I'll see where it takes me. I currently have a system where you can buy items. The items cost a specified amount of gold, silver, diamonds etc. When you have selected and bought the item, it takes time before getting rewarded. When time is over, you are getting rewarded with other properties (gold, energy, diamonds). For example, you can buy an apple for 50gold, It takes a minute, you get rewarded with 75energy. Or if you take a run, it cost 50energy, it takes 5minutes, reward is 25gold and 25silver. These definitions is what i call actions. Currently I already have a system where this already works and I can define as much actions with as much properties as I want. The definitions I have kinda looks like this: {id:101, category:544, onInit:{gold:-75}, onComplete:{energy:75}, time:2000, name:"Apple", locked: false} {id:102, category:544, onInit:{gold:-135}, onComplete:{energy:145}, time:2000, name:"Banana", locked: false} {id:106, category:302, onInit:{energy:-50, power: -25}, onComplete:{gold:100, diamonds:2}, time:10000, name:"Run", locked: false} {id:107, category:302, onInit:{energy:-70, silver: -55}, onComplete:{gold:100}, time:10000, name:"Dance", locked: false} {id:108, category:302, onInit:{energy:-230, power: -355}, onComplete:{gold:70, silver:70}, time:10000, name:"Fitness", locked: false} Now, I would love to add a system where I can lock/unlock the actions using achievement rules. Lets say, if you buy 10 apples, you unlock a new action, like bananas which cost more, and reward more. In the future I maybe want to restrict achievements and actions to levels. I am kinda stuck how to structure this. I have 2 questions: Which patterns are used to define achievements? How/where are they defined? Should it be part of the action, or should it be a separate controller? Is it a good idea to register all completed actions to it? I think I want multiple types of achievement rules, Id love to hear some ideas how to develop it. How do you create/find a good balance, so the user does not get stuck or can cheat by repeat a pattern of actions to get too much rewards. I know there is not a simple answer and i'm lacking of a good game-concept, but I wonder if anyone created such a game and how you dealed and played with it.

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  • Z-order with Alpha blending in a 3D world

    - by user41765
    I'm working on a game in a 3D world with 2D sprites only (like Don't Starve game). (OpenGL ES2 with C++) Currently, I'm ordering elements back to front before drawing them without batch (so 1 element = 1 drawcall). I would like to implement batching in my framework to decrease draw calls. Here is what I've got for the moment: Order all elements of my scene back to front. Send order list of elements to the Renderer. Renderer look in his batch manager if a batch exist for the given element with his Material. Batch didn't exist: create a new one. Batch exist for element with this Material: Add sprite to the batch. Compute big mesh with all sprite for each batch (1 material type = 1 batch). When all batches are ok, the batch manager compute draw commands for the renderer. Renderer process draw commands (bind shader, bind textures, bind buffers, draw element) Image with my problem here: Explication here But I've got some problems because objects can be behind another objects inside another batch. How can I do something like that? Thanks!

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  • Euler angles to Cartesian Coordinates for use with gluLookAt

    - by notrodash
    I have searched all of the internet but just couldn't find the answer. I am using LibGDX and this is part of my code that loops over and over: public void render() { GL11 gl = Gdx.gl11; float centerX = (float)Math.cos(yaw) * (float)Math.cos(pitch); float centerY = (float)Math.sin(yaw) * (float)Math.cos(pitch); float centerZ = (float)Math.sin(pitch); System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z); Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0); if(Gdx.input.isKeyPressed(Keys.A)) { yaw--; } if(Gdx.input.isKeyPressed(Keys.D)) { yaw++; } } I might just be bad at the math, but I dont get it. Does someone have a good explanation and an idea about how to deal with this? I am trying to make a first person camera. By the way, the camera is translated by +10 on the Z axis. Currently when I run the application, this is what I get: Watch video in browser | Download video (for those who cant download the video, everything shakes in a clockwise/anticlockwise action, depending on if I increase or decrease the Yaw value) -Thank you. [edit] and with this code: public void render() { GL11 gl = Gdx.gl11; float centerX = (float)(MathUtils.cosDeg(yaw)*4); float centerY = 0; float centerZ = (float)(MathUtils.sinDeg(yaw)*4); System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z); Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0); if(Gdx.input.isKeyPressed(Keys.A)) { yaw--; } if(Gdx.input.isKeyPressed(Keys.D)) { yaw++; } } it slowly swings from the left to the right. This approach worked for turning left and right for 2d games though. What am I doing wrong?

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  • Fixed-Function vs Shaders: Which for beginner?

    - by Rob Hays
    I'm currently going to college for computer science. Although I do plan on utilizing an existing engine at some point to create a small game, my aim right now is towards learning the fundamentals: namely, 3D programming. I've already done some research regarding the choice between DirectX and OpenGL, and the general sentiment that came out of that was that whether you choose OpenGL or DirectX as your training-wheels platform, a lot of the knowledge is transferrable to the other platform. Therefore, since OpenGL is supported by more systems (probably a silly reason to choose what to learn), I decided that I'm going to learn OpenGL first. After I made this decision to learn OpenGL, I did some more research and found out about a dichotomy that I was somewhere unaware of all this time: fixed-function OpenGL vs. modern programmable shader-based OpenGL. At first, I thought it was an obvious choice that I should choose to learn shader-based OpenGL since that's what's most commonly used in the industry today. However, I then stumbled upon the very popular Learning Modern 3D Graphics Programming by Jason L. McKesson, located here: http://www.arcsynthesis.org/gltut/ I read through the introductory bits, and in the "About This Book" section, the author states: "First, much of what is learned with this approach must be inevitably abandoned when the user encounters a graphics problem that must be solved with programmability. Programmability wipes out almost all of the fixed function pipeline, so the knowledge does not easily transfer." yet at the same time also makes the case that fixed-functionality provides an easier, more immediate learning curve for beginners by stating: "It is generally considered easiest to teach neophyte graphics programmers using the fixed function pipeline." Naturally, you can see why I might be conflicted about which paradigm to learn: Do I spend a lot of time learning (and then later unlearning) the ways of fixed-functionality, or do I choose to start out with shaders? My primary concern is that modern programmable shaders somehow require the programmer to already understand the fixed-function pipeline, but I doubt that's the case. TL;DR == As an aspiring game graphics programmer, is it in my best interest to learn 3D programming through fixed-functionality or modern shader-based programming?

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  • How do I check on non-transparent pixels in a bitmapdata?

    - by Opoe
    I'm still working on my window cleaning game from one of my previous questions I marked a contribution as my answer, but after all this time I can't get it to work and I have to many questions about this so I decided to ask some more about it. As a sequel on my mentioned previous question, my question to you is: How can I check whether or not a bitmapData contains non transparent pixels? Subquestion: Is this possible when the masked image is a movieclip? Shouldn't I use graphics instead? Information I have: A dirtywindow movieclip on the bottom layer and a clean window movieclip on layer 2(mc1) on the layer above. To hide the top layer(the dirty window) I assign a mask to it. Code // this creates a mask that hides the movieclip on top var mask_mc:MovieClip = new MovieClip(); addChild(mask_mc) //assign the mask to the movieclip it should 'cover' mc1.mask = mask_mc; With a brush(cursor) the player wipes of the dirt ( actualy setting the fill from the mask to transparent so the clean window appears) //add event listeners for the 'brush' brush_mc.addEventListener(MouseEvent.MOUSE_DOWN,brushDown); brush_mc.addEventListener(MouseEvent.MOUSE_UP,brushUp); //function to drag the brush over the mask function brushDown(dragging:MouseEvent):void{ dragging.currentTarget.startDrag(); MovieClip(dragging.currentTarget).addEventListener(Event.ENTER_FRAME,erase) ; mask_mc.graphics.moveTo(brush_mc.x,brush_mc.y); } //function to stop dragging the brush over the mask function brushUp(dragging:MouseEvent):void{ dragging.currentTarget.stopDrag(); MovieClip(dragging.currentTarget).removeEventListener(Event.ENTER_FRAME,erase); } //fill the mask with transparant pixels so the movieclip turns visible function erase(e:Event):void{ with(mask_mc.graphics){ beginFill(0x000000); drawRect(brush_mc.x,brush_mc.y,brush_mc.width,brush_mc.height); endFill(); } }

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  • How can I resolve collisions at different speeds, depending on the direction?

    - by Raven Dreamer
    I have, for all intents and purposes, a Triangle class that objects in my scene can collide with (In actuality, the right side of a parallelogram). My collision detection and resolution code works fine for the purposes of preventing a gameobject from entering into the space of the Triangle, instead directing the movement along the edge. The trouble is, the maximum speed along the x and y axis is not equivalent in my game, and moving along the Y axis (up or down) should take twice as long as an equivalent distance along the X axis (left or right). Unfortunately, these speeds apply to the collision resolution too, and movement along the blue path above progresses twice as fast. What can I do in my collision resolution to make sure that the speedlimit for Y axis movement is obeyed in the latter case? Collision Resolution for this case below (vecInput and velocity are the position and velocity vectors of the game object): // y = mx+c // solve for y. M = 2, x = input's x coord, c = rightYIntercept lowY = 2*vecInput.x + parag.rightYIntercept ; ... else { // y = mx+c // vecInput.y = 2(x) + RightYIntercept // (vecInput.y - RightYIntercept) / 2 = x; //if velocity.Y (positive) greater than velocity.X (negative) //pushing from bottom, so push right. if(velocity.y > -1*velocity.x) { //change the input vector's x position to match the //y position on the shape's edge. Formula for line: Y = MX+C // M is 2, C is rightYIntercept, y is the input y, solve for X. vecInput = new Vector2((vecInput.y - parag.rightYIntercept)/2, vecInput.y); Debug.Log("adjusted rightwards"); } else { vecInput = new Vector2( vecInput.x, lowY); Debug.Log("adjusted downwards"); } }

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  • How to create an extensible rope in Box2D?

    - by Thomas
    Let's say I'm trying to create a ninja lowering himself down a rope, or pulling himself back up, all whilst he might be swinging from side to side or hit by objects. Basically like http://ninja.frozenfractal.com/ but with Box2D instead of hacky JavaScript. Ideally I would like to use a rope joint in Box2D that allows me to change the length after construction. The standard Box2D RopeJoint doesn't offer that functionality. I've considered a PulleyJoint, connecting the other end of the "pulley" to an invisible kinematic body that I can control to change the length, but PulleyJoint is more like a rod than a rope: it constrains maximum length, but unlike RopeJoint it constrains the minimum as well. Re-creating a RopeJoint every frame using a new length is rather inefficient, and I'm not even sure it would work properly in the simulation. I could create a "chain" of bodies connected by RotationJoints but that is also less efficient, and less robust. I also wouldn't be able to change the length arbitrarily, but only by adding and removing a whole number of links, and it's not obvious how I would connect the remainder without violating existing joints. This sounds like something that should be straightforward to do. Am I overlooking something?

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  • 3D Paint tool in Maya

    - by Joris
    Hey everyone, could someone help me out on this question? When I am trying to texture objects in maya (for example a barrel) I want to texture it with a brush. When I try to use the 3D painting tool it al gets black even when I have a image file selected. Also the resolution is very very low of the models and textures in maya, though the texture image is very high quality. Can someone please help me? Thanks so much for helping.

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  • Level of detail algorithm not functioning correctly

    - by Darestium
    I have been working on this problem for months; I have been creating Planet Generator of sorts, after more than 6 months of work I am no closer to finishing it then I was 4 months ago. My problem; The terrain does not subdivide in the correct locations properly, it almost seems as if there is a ghost camera next to me, and the quads subdivide based on the position of this "ghost camera". Here is a video of the broken program: http://www.youtube.com/watch?v=NF_pHeMOju8 The best example of the problem occurs around 0:36. For detail limiting, I am going for a chunked LOD approach, which subdivides the terrain based on how far you are away from it. I use a "depth table" to determine how many subdivisions should take place. void PQuad::construct_depth_table(float distance) { tree[0] = -1; for (int i = 1; i < MAX_DEPTH; i++) { tree[i] = distance; distance /= 2.0f; } } The chuncked LOD relies on the child/parent structure of quads, the depth is determined by a constant e.g: if the constant is 6, there are six levels of detail. The quads which should be drawn go through a distance test from the player to the centre of the quad. void PQuad::get_recursive(glm::vec3 player_pos, std::vector<PQuad*>& out_children) { for (size_t i = 0; i < children.size(); i++) { children[i].get_recursive(player_pos, out_children); } if (this->should_draw(player_pos) || this->depth == 0) { out_children.emplace_back(this); } } bool PQuad::should_draw(glm::vec3 player_position) { float distance = distance3(player_position, centre); if (distance < tree[depth]) { return true; } return false; } The root quad has four children which could be visualized like the following: [] [] [] [] Where each [] is a child. Each child has the same amount of children up until the detail limit, the quads which have are 6 iterations deep are leaf nodes, these nodes have no children. Each node has a corresponding Mesh, each Mesh structure has 16x16 Quad-shapes, each Mesh's Quad-shapes halves in size each detail level deeper - creating more detail. void PQuad::construct_children() { // Calculate the position of the Quad based on the parent's location calculate_position(); if (depth < (int)MAX_DEPTH) { children.reserve((int)NUM_OF_CHILDREN); for (int i = 0; i < (int)NUM_OF_CHILDREN; i++) { children.emplace_back(PQuad(this->face_direction, this->radius)); PQuad *child = &children.back(); child->set_depth(depth + 1); child->set_child_index(i); child->set_parent(this); child->construct_children(); } } else { leaf = true; } } The following function creates the vertices for each quad, I feel that it may play a role in the problem - I just can't determine what is causing the problem. void PQuad::construct_vertices(std::vector<glm::vec3> *vertices, std::vector<Color3> *colors) { vertices->reserve(quad_width * quad_height); for (int y = 0; y < quad_height; y++) { for (int x = 0; x < quad_width; x++) { switch (face_direction) { case YIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, quad_height - 1.0f, -(position.y + y * element_width))); break; case YDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, 0.0f, -(position.y + y * element_width))); break; case XIncreasing: vertices->emplace_back(glm::vec3(quad_width - 1.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case XDecreasing: vertices->emplace_back(glm::vec3(0.0f, position.y + y * element_width, -(position.x + x * element_width))); break; case ZIncreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, 0.0f)); break; case ZDecreasing: vertices->emplace_back(glm::vec3(position.x + x * element_width, position.y + y * element_width, -(quad_width - 1.0f))); break; } // Position the bottom, right, front vertex of the cube from being (0,0,0) to (-16, -16, 16) (*vertices)[vertices->size() - 1] -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); colors->emplace_back(Color3(255.0f, 255.0f, 255.0f, false)); } } switch (face_direction) { case YIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, quad_height - 1.0f, -(position.y + quad_height / 2.0f)); break; case YDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, 0.0f, -(position.y + quad_height / 2.0f)); break; case XIncreasing: this->centre = glm::vec3(quad_width - 1.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case XDecreasing: this->centre = glm::vec3(0.0f, position.y + quad_height / 2.0f, -(position.x + quad_width / 2.0f)); break; case ZIncreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, 0.0f); break; case ZDecreasing: this->centre = glm::vec3(position.x + quad_width / 2.0f, position.y + quad_height / 2.0f, -(quad_height - 1.0f)); break; } this->centre -= glm::vec3(quad_width / 2.0f, quad_width / 2.0f, -(quad_width / 2.0f)); } Any help in discovering what is causing this "subdivding in the wrong place" would be greatly appreciated.

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  • XNA: Huge Tile Map, long load times

    - by Zach
    Recently I built a tile map generator for a game project. What I am very proud of is that I finally got it to the point where I can have a GIANT 2D map build perfectly on my PC. About 120000pixels by 40000 pixels. I can go larger actually, but I have only 1 draw back. #1 ram, the map currently draws about 320MB of ram and I know the Xbox allows 512MB I think? #2 It takes 20 mins for the map to build then display on the Xbox, on my PC it take less then a few seconds. I need to bring that 20 minutes of generating from 20 mins to how ever little bit I can, and how can a lower the amount of RAM usage while still being able to generate my map. Right now everything is stored in Jagged Arrays, each piece generating in a size of 1280x720 (the mother piece). Up to the amount that I need, every block is exactly 40x40 pixels however the blocks get removed from a List or regenerated in a List depending how close the mother piece is to the player. Saving A LOT of CPU, so at all times its no more then looping through 5184 some blocks. Well at least I'm sure of this. But how can I lower my RAM usage without hurting the size of the map, and how can I lower these INSANE loading times? EDIT: Let me explain my self better. Also I'd like to let everyone know now that I'm inexperienced with many of these things. So here is an example of the arrays I'm using. Here is the overall in a shorter term: int[][] array = new int[30][]; array[0] = new int[] { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }; array[1] = new int[] { 1, 3, 3, 3, 3, 1, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 }; that goes on for around 30 arrays downward. Now for every time it hits a 1, it goes and generates a tile map 1280x720 and it does that exactly the way it does it above. This is how I loop through those arrays: for (int i = 0; i < array.Length; i += 1) { for (int h = 0; h < array[i].Length; h += 1) { } { Now how the tiles are drawn and removed is something like this: public void Draw(SpriteBatch spriteBatch, Vector2 cam) { if (cam.X >= this.Position.X - 1280) { if (cam.X <= this.Position.X + 2560) { if (cam.Y >= this.Position.Y - 720) { if (cam.Y <= this.Position.Y + 1440) { if (visible) { if (once == 0) { once = 1; visible = false; regen(); } } for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles[i].Draw(spriteBatch, cam); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles[i].Draw(spriteBatch, cam); } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } else { once = 0; for (int i = Tiles.Count - 1; i >= 0; i--) { Tiles.RemoveAt(i); } for (int i = unWalkTiles.Count - 1; i >= 0; i--) { unWalkTiles.RemoveAt(i); } } } } If you guys still need more information just ask in the comments.

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  • Trouble with touch events on iPhone

    - by MrDatabase
    I'm making a simple 2D game for iPhone. Think of the game as a ball on the screen that goes up while the user is touching the screen and falls down when the user stops touching the screen. The ball starts moving up in touchesBegan:withEvent and starts moving down in touchesEnded:withEvent. This works fine almost all the time. However on occasion the ball will keep moving up after the user stops touching... or the ball will keep moving down while the user is touching. Why is this happening? Just fyi the ball is drawn on a UIWindow. The taps are handled by a UIImageview subclass that's clearColor and takes up the entire screen. This "touchLayer" is also moved to the front of the window in the game loop. Any idea why this control scheme occasionally fails? Perhaps the touch events just aren't firing? Or they're fired out of order? Cheers!

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  • Queries regarding Geometry Shaders

    - by maverick9888
    I am dealing with geometry shaders using GL_ARB_geometry_shader4 extension. My code goes like : GLfloat vertices[] = { 0.5,0.25,1.0, 0.5,0.75,1.0, -0.5,0.75,1.0, -0.5,0.25,1.0, 0.6,0.35,1.0, 0.6,0.85,1.0, -0.6,0.85,1.0, -0.6,0.35,1.0 }; glProgramParameteriEXT(psId, GL_GEOMETRY_INPUT_TYPE_EXT, GL_TRIANGLES); glProgramParameteriEXT(psId, GL_GEOMETRY_OUTPUT_TYPE_EXT, GL_TRIANGLE_STRIP); glLinkProgram(psId); glBindAttribLocation(psId,0,"Position"); glEnableVertexAttribArray (0); glVertexAttribPointer(0, 3, GL_FLOAT, 0, 0, vertices); glDrawArrays(GL_TRIANGLE_STRIP,0,4); My vertex shader is : #version 150 in vec3 Position; void main() { gl_Position = vec4(Position,1.0); } Geometry shader is : #version 150 #extension GL_EXT_geometry_shader4 : enable in vec4 pos[3]; void main() { int i; vec4 vertex; gl_Position = pos[0]; EmitVertex(); gl_Position = pos[1]; EmitVertex(); gl_Position = pos[2]; EmitVertex(); gl_Position = pos[0] + vec4(0.3,0.0,0.0,0.0); EmitVertex(); EndPrimitive(); } Nothing is rendered with this code. What exactly should be the mode in glDrawArrays() ? How does the GL_GEOMETRY_OUTPUT_TYPE_EXT parameter will affect glDrawArrays() ? What I expect is 3 vertices will be passed on to Geometry Shader and using those we construct a primitive of size 4 (assuming GL_TRIANGLE_STRIP requires 4 vertices). Can somebody please throw some light on this ?

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  • How to move a directional light according to the camera movement?

    - by Andrea Benedetti
    Given a light direction, how can I move it according to the camera movement, in a shader? Think that an artist has setup a scene (e.g., in 3DSMax) with a mesh in center of that and a directional light with a position and a target. From this position and target I've calculated the light direction. Now I want to use the same direction in my lighting equation but, obviously, I want that this light moves correctly with the camera. Thanks.

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  • Repeat a part of spritesheet as background

    - by Moiblpadde
    So I'm trying to repeat a part of my spritesheet as a background (js, canvas). My code so far: var canvas = $("#board")[0], ctx = canvas.getContext("2d"), sprite = new Image(); sprite.src = "spritesheet.png"; sprite.onload = function(){ ctx.fillStyle = ctx.createPattern(spriteBg, "repeat"); ctx.fillRect(0, 25, 500, 500); } This is fine, but as you can see, it repeat the whole sprite, not just a part of it, and I just can't figure out how to do it D:

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  • 2D Grid Map Connectivity Check (avoiding stack overflow)

    - by SombreErmine
    I am trying to create a routine in C++ that will run before a more expensive A* algorithm that checks to see if two nodes on a 2D grid map are connected or not. What I need to know is a good way to accomplish this sequentially rather than recursively to avoid overflowing the stack. What I've Done Already I've implemented this with ease using a recursive algorithm; however, depending upon different situations it will generate a stack overflow. Upon researching this, I've come to the conclusion that it is overflowing the stack because of too many recursive function calls. I am sure that my recursion does not enter an infinite loop. I generate connected sets at the beginning of the level, and then I use those connected sets to determine connectivity on the fly later. Basically, the generating algorithm starts from left-to-right top-to-bottom. It skips wall nodes and marks them as visited. Whenever it reaches a walkable node, it recursively checks in all four cardinal directions for connected walkable nodes. Every node that gets checked is marked as visited so they aren't handled twice. After checking a node, it is added to either a walls set, a doors set, or one of multiple walkable nodes sets. Once it fills that area, it continues the original ltr ttb loop skipping already-visited nodes. I've also looked into flood-fill algorithms, but I can't make sense of the sequential algorithms and how to adapt them. Can anyone suggest a better way to accomplish this without causing a stack overflow? The only way I can think of is to do the left-to-right top-to-bottom loop generating connected sets on a row basis. Then check the previous row to see if any of the connected sets are connected and then join the sets that are. I haven't decided on the best data structures to use for that though. I also just thought about having the connected sets pre-generated outside the game, but I wouldn't know where to start with creating a tool for that. Any help is appreciated. Thanks!

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  • Understanding how OpenGL blending works

    - by yuumei
    I am attempting to understand how OpenGL (ES) blending works. I am finding it difficult to understand the documentation and how the results of glBlendFunc and glBlendEquation effect the final pixel that is written. Do the source and destination out of glBlendFunc get added together with GL_FUNC_ADD by default? This seems wrong because "basic" blending of GL_ONE, GL_ONE would output 2,2,2,2 then (Source giving 1,1,1,1 and dest giving 1,1,1,1). I have written the following pseudo-code, what have I got wrong? struct colour { float r, g, b, a; }; colour blend_factor( GLenum factor, colour source, colour destination, colour blend_colour ) { colour colour_factor; float i = min( source.a, 1 - destination.a ); // From http://www.khronos.org/opengles/sdk/docs/man/xhtml/glBlendFunc.xml switch( factor ) { case GL_ZERO: colour_factor = { 0, 0, 0, 0 }; break; case GL_ONE: colour_factor = { 1, 1, 1, 1 }; break; case GL_SRC_COLOR: colour_factor = source; break; case GL_ONE_MINUS_SRC_COLOR: colour_factor = { 1 - source.r, 1 - source.g, 1 - source.b, 1 - source.a }; break; // ... } return colour_factor; } colour blend( colour & source, colour destination, GLenum source_factor, // from glBlendFunc GLenum destination_factor, // from glBlendFunc colour blend_colour, // from glBlendColor GLenum blend_equation // from glBlendEquation ) { colour source_colour = blend_factor( source_factor, source, destination, blend_colour ); colour destination_colour = blend_factor( destination_factor, source, destination, blend_colour ); colour output; // From http://www.khronos.org/opengles/sdk/docs/man/xhtml/glBlendEquation.xml switch( blend_equation ) { case GL_FUNC_ADD: output = add( source_colour, destination_colour ); case GL_FUNC_SUBTRACT: output = sub( source_colour, destination_colour ); case GL_FUNC_REVERSE_SUBTRACT: output = sub( destination_colour, source_colour ); } return output; } void do_pixel() { colour final_colour; // Blending if( enable_blending ) { final_colour = blend( current_colour_output, framebuffer[ pixel ], ... ); } else { final_colour = current_colour_output; } } Thanks!

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  • Group Matchmaking

    - by Simon Kérouack
    Consider different groups(1 or more players) queuing together, we want to make 2 opposing teams containing each the same amount of players while keeping the groups together. At the same time we want to make both teams' average ranking as close as possible. Now also consider we have as a working set the subset of groups currently queuing within a given ranking range. For an example, let's say we have the following groups, ordered by queuing time: Id, playerCount, totalRank, avgRank 0, 3, 126, 42 1, 2, 60, 30 2, 1, 25, 25 3, 2, 80, 40 4, 1, 40, 40 5, 1, 20, 20 6, 3, 150, 50 for this specific subset, the expected output should ideally be: team1: 0, 1 (total: 186) team2: 2, 5, 6 (total: 195) up to now the solution I have been using is to balance out each team by making each team pick the group with highest ranking within the subset turn by turn. The team who picks is the one with the currently lowest average rank unless one is already full. If one team is already full the other team tries to complete itself with groups that would make the rank gap as small as possible. This solution turns out to have issues with frequent edge cases and I'm looking for a better solution, or some fine-tuning that could be made. In most cases, players seems to want teams of 5 people and queue in group of 2. Our average subset when 2 teams of 5 are chosen is made of about 14 players if that may be of any help.

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  • In-Game Encyclopedias

    - by SHiNKiROU
    There are some games where there is an in-game encyclopedia where you can know many things about characters and settings of the game. For example, the Codex in Mass Effect. I want to know if it is exclusive to Bioware, and get inspired about other encyclopedia systems. What are some other examples of in-game encyclopedias? How effective is it? I also want some examples where the in-game encyclopedia is not effective at all or an ignored feature

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  • How to properly add texture to multi-fixture/shape b2Body

    - by Blazej Wdowikowski
    Hello to everyone this is my first poste here I hope that will be not fail start. At start I must say I make part 1 in Ray's Tutorial "How To Make A Game Like Fruit Ninja With Box2D and Cocos2D". But I wonder what when I want make more complex body with texture? Simple just add n b2FixtureDef to the same body. OK but what about texture? If I will take code from that tutorial it only fill last fixture. Probably it does not takes every b2Vec2 point. I was right, it did not. So quick refactor and from that -(id)initWithTexture:(CCTexture2D*)texture body:(b2Body*)body original:(BOOL)original { // gather all the vertices from our Box2D shape b2Fixture *originalFixture = body->GetFixtureList(); b2PolygonShape *shape = (b2PolygonShape*)originalFixture->GetShape(); int vertexCount = shape->GetVertexCount(); NSMutableArray *points = [NSMutableArray arrayWithCapacity:vertexCount]; for(int i = 0; i < vertexCount; i++) { CGPoint p = ccp(shape->GetVertex(i).x * PTM_RATIO, shape->GetVertex(i).y * PTM_RATIO); [points addObject:[NSValue valueWithCGPoint:p]]; } if ((self = [super initWithPoints:points andTexture:texture])) { _body = body; _body->SetUserData(self); _original = original; // gets the center of the polygon _centroid = self.body->GetLocalCenter(); // assign an anchor point based on the center self.anchorPoint = ccp(_centroid.x * PTM_RATIO / texture.contentSize.width, _centroid.y * PTM_RATIO / texture.contentSize.height); } return self; } I came up with that -(id)initWithTexture:(CCTexture2D*)texture body:(b2Body*)body original:(BOOL)original { int vertexCount = 0; //gather total number of b2Vect2 points b2Fixture *currentFixture = body->GetFixtureList(); while (currentFixture) { //new b2PolygonShape *shape = (b2PolygonShape*)currentFixture->GetShape(); vertexCount += shape->GetVertexCount(); currentFixture = currentFixture->GetNext(); } NSMutableArray *points = [NSMutableArray arrayWithCapacity:vertexCount]; // gather all the vertices from our Box2D shape b2Fixture *originalFixture = body->GetFixtureList(); while (originalFixture) { //new NSLog((NSString*)@"-"); b2PolygonShape *shape = (b2PolygonShape*)originalFixture->GetShape(); int currentVertexCount = shape->GetVertexCount(); for(int i = 0; i < currentVertexCount; i++) { CGPoint p = ccp(shape->GetVertex(i).x * PTM_RATIO, shape->GetVertex(i).y * PTM_RATIO); [points addObject:[NSValue valueWithCGPoint:p]]; } originalFixture = originalFixture->GetNext(); } if ((self = [super initWithPoints:points andTexture:texture])) { _body = body; _body->SetUserData(self); _original = original; // gets the center of the polygon _centroid = self.body->GetLocalCenter(); // assign an anchor point based on the center self.anchorPoint = ccp(_centroid.x * PTM_RATIO / texture.contentSize.width,_centroid.y * PTM_RATIO / texture.contentSize.height); } return self; } I was working for simple two fixtures body like b2BodyDef bodyDef; bodyDef.type = b2_dynamicBody; bodyDef.position = position; bodyDef.angle = rotation; b2Body *body = world->CreateBody(&bodyDef); b2FixtureDef fixtureDef; fixtureDef.density = 1.0; fixtureDef.friction = 0.5; fixtureDef.restitution = 0.2; fixtureDef.filter.categoryBits = 0x0001; fixtureDef.filter.maskBits = 0x0001; b2Vec2 vertices[] = { b2Vec2(0.0/PTM_RATIO,50.0/PTM_RATIO), b2Vec2(0.0/PTM_RATIO,0.0/PTM_RATIO), b2Vec2(50.0/PTM_RATIO,30.1/PTM_RATIO), b2Vec2(60.0/PTM_RATIO,60.0/PTM_RATIO) }; b2PolygonShape shape; shape.Set(vertices, 4); fixtureDef.shape = &shape; body->CreateFixture(&fixtureDef); b2Vec2 vertices2[] = { b2Vec2(20.0/PTM_RATIO,50.0/PTM_RATIO), b2Vec2(20.0/PTM_RATIO,0.0/PTM_RATIO), b2Vec2(70.0/PTM_RATIO,30.1/PTM_RATIO), b2Vec2(80.0/PTM_RATIO,60.0/PTM_RATIO) }; shape.Set(vertices2, 4); fixtureDef.shape = &shape; body->CreateFixture(&fixtureDef); But if I try put secondary shape upper than first it starting wierd, texture goes crazy. For example not mention about more complex shapes. What's more if shapes have one common point texture will not render for them at all [For that I use Physics Edytor like in tutorial part1] BTW. I use PolygonSprite and in method createWithWorld... another shapes. Uff.. Question So my question is, why texture coords are in such a mess up? It's my modify method or just wrong approach? Maybe I should remove duplicated from points array?

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  • Turn-based JRPG battle system architecture resources

    - by BenoitRen
    The past months I've been busy programming a 2D JRPG (Japanese-style RPG) in C++ using the SDL library. The exploration mode is more or less done. Now I'm tackling the battle mode. I have been unable to find any resources about how a classic turn-based JRPG battle system is structured. All I find are discussions about damage formula. I've tried googling, searching gamedev.net's message board, and crawling through C++-related questions here on Stack Exchange. I've also tried reading source code of existing open source RPGs, but without a guide of some sort it's like trying to find a needle in a haystack. I'm not looking for a set of rules like D&D or anything similar. I'm talking purely about code and object structure design. A battle system asks the player for input using menus. Next the battle turn is executed as the heroes and the enemies execute their actions. Can anyone point me in the right direction? Thanks in advance.

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  • Unity Occlusion Portals: What and How?

    - by Nick Wiggill
    (Here I eat my words on Meta about posting Unity questions on Unity Answers... since that site is less responsive than this one.) Unity provides cell-based Occlusion Culling (via Umbra, I believe). However, a newer feature that it supports is Occlusion Portals. The question is, if BSP-based occlusion culling is already a feature of Unity, what do portals add, and how? PS. This question is not "What are portals?" -- I'm aware of the original Quake BSP-style portals -- which is partly why I find the explicit portal concept in Unity odd, since it uses BSP anyway.

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  • How do I properly use multithreading with Nvidia PhysX?

    - by xcrypt
    I'm having a multithreading problem with Nvidia PhysX. the SDK requires that you call Simulate() (starts computing new physics positions within a new thread) and FetchResults() (waits 'till the physics computations are done). Inbetween Simulate() and FetchResults() you may not "compute new physics". It is proposed (in a sample) that we create a game loop as such: Logic (you may calculate physics here and other stuff) Render + Simulate() at start of Render call and FetchResults at end of Render() call However, this has given me various little errors that stack up: since you actually render the scene that was computed in the previous iteration in the game loop. Does anyone have a solution to this?

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  • What platform were old TV video games developed on?

    - by Mihir
    I am very eager to know how TV video games (which we all used to play in our childhood) were developed and on which platform. I know how games are developed for mobile devices, Windows PC's and Mac but I'm not getting how (in those days) Contra, Duck Hunt and all those games were developed. As they have high graphics and a large number of stages. So how did they manage to develop games in such a small size environment and with lower configuration platform?

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