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• Creating smooth lighting transitions using tiles in HTML5/JavaScript game

  - by user12098

  I am trying to implement a lighting effect in an HTML5/JavaScript game using tile replacement. What I have now is kind of working, but the transitions do not look smooth/natural enough as the light source moves around. Here's where I am now: Right now I have a background map that has a light/shadow spectrum PNG tilesheet applied to it - going from darkest tile to completely transparent. By default the darkest tile is drawn across the entire level on launch, covering all other layers etc. I am using my predetermined tile sizes (40 x 40px) to calculate the position of each tile and store its x and y coordinates in an array. I am then spawning a transparent 40 x 40px "grid block" entity at each position in the array The engine I'm using (ImpactJS) then allows me to calculate the distance from my light source entity to every instance of this grid block entity. I can then replace the tile underneath each of those grid block tiles with a tile of the appropriate transparency. Currently I'm doing the calculation like this in each instance of the grid block entity that is spawned on the map: var dist = this.distanceTo( ig.game.player ); var percentage = 100 * dist / 960; if (percentage < 2) { // Spawns tile 64 of the shadow spectrum tilesheet at the specified position ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 64 ); } else if (percentage < 4) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 63 ); } else if (percentage < 6) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 62 ); } // etc... (sorry about the weird spacing, I still haven't gotten the hang of pasting code in here properly) The problem is that like I said, this type of calculation does not make the light source look very natural. Tile switching looks too sharp whereas ideally they would fade in and out smoothly using the spectrum tilesheet (I copied the tilesheet from another game that manages to do this, so I know it's not a problem with the tile shades. I'm just not sure how the other game is doing it). I'm thinking that perhaps my method of using percentages to switch out tiles could be replaced with a better/more dynamic proximity forumla of some sort that would allow for smoother transitions? Might anyone have any ideas for what I can do to improve the visuals here, or a better way of calculating proximity with the information I'm collecting about each tile? (PS: I'm reposting this from Stack Overflow at someone's suggestion, sorry about the duplicate!)

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• 2D camera perspective projection from 3D coordinates -- HOW?

  - by Jack

  I am developing a camera for a 2D game with a top-down view that has depth. It's almost a 3D camera. Basically, every object has a Z even though it is in 2D, and similarly to parallax layers their position, scale and rotation speed vary based on their Z. I guess this would be a perspective projection. But I am having trouble converting the objects' 3D coordinates into the 2D space of the screen so that everything has correct perspective and scale. I never learned matrices though I did dig the topic a bit today. I tried without using matrices thanks to this article but every attempt gave awkward results. I'm using ActionScript 3 and Flash 11+ (Starling), where the screen coordinates work like this: Left-handed coordinates system illustration I can explain further what I did if you want to help me sort out what's wrong, or you can directly tell me how you would do it properly. In case you prefer the former, read on. These are images showing the formulas I used: upload.wikimedia.org/math/1/c/8/1c89722619b756d05adb4ea38ee6f62b.png upload.wikimedia.org/math/d/4/0/d4069770c68cb8f1aa4b5cfc57e81bc3.png (Sorry new users can't post images, but both are from the wikipedia article linked above, section "Perspective projection". That's where you'll find what all variables mean, too) The long formula is greatly simplified because I believe a normal top-down 2D camera has no X/Y/Z rotation values (correct ?). Then it becomes d = a - c. Still, I can't get it to work. Maybe you could explain what numbers I should put in a(xyz), c(xyz), theta(xyz), and particularly, e(xyz) ? I don't quite get how e is different than c in my case. c.z is also an issue to me. If the Z of the camera's target object is 0, should the camera's Z be something like -600 ? ( = focal length of 600) Whatever I do, it's wrong. I only got it to work when I used arbitrary calculations that "looked" right, like most cameras with parallax layers seem to do, but that's fake! ;) If I want objects to travel between Z layers I might as well do it right. :) Thanks a lot for your help!

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• Compressing 2D level data

  - by Lucius

  So, I'm developing a 2D, tile based game and a map maker thingy - all in Java. The problem is that recently I've been having some memory issues when about 4 maps are loaded. Each one of these maps are composed of 128x128 tiles and have 4 layers (for details and stuff). I already spent a good amount of time searching for solutions and the best thing I found was run-length enconding (RLE). It seems easy enough to use with static data, but is there a way to use it with data that is constantly changing, without a big drop in performance? In my maps, supposing I'm compressing the columns, I would have 128 rows, each with some amount of data (hopefully less than it would be without RLE). Whenever I change a tile, that whole row would have to be checked and I'm affraid that would slow down too much the production (and I'm in a somewhat tight schedule). Well, worst case scenario I work on each map individually, and save them using RLE, but it would be really nice if I could avoind that. EDIT: What I'm currently using to store the data for the tiles is a 2D array of HashMaps that use the layer as key and store the id of the tile in that position - like this: private HashMap< Integer, Integer [][]

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• Checking for alternate keys with XNA IsKeyDown

  - by jocull

  I'm working on picking up XNA and this was a confusing point for me. KeyboardState keyState = Keyboard.GetState(); if (keyState.IsKeyDown(Keys.Left) || keyState.IsKeyDown(Keys.A)) { //Do stuff... } The book I'm using (Learning XNA 4.0, O'Rielly) says that this method accepts a bitwise OR series of keys, which I think should look like this... KeyboardState keyState = Keyboard.GetState(); if (keyState.IsKeyDown(Keys.Left | Keys.A)) { //Do stuff... } But I can't get it work. I also tried using !IsKeyUp(... | ...) as it said that all keys had to be down for it to be true, but had no luck with that either. Ideas? Thanks.

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• Generate texture for a heightmap

  - by James

  I've recently been trying to blend multiple textures based on the height at different points in a heightmap. However i've been getting poor results. I decided to backtrack and just attempt to recreate one single texture from an SDL_Surface (i'm using SDL) and just send that into opengl. I'll put my code for creating the texture and reading the colour values. It is a 24bit TGA i'm loading, and i've confirmed that the rest of my code works because i was able to send the surfaces pixels directly to my createTextureFromData function and it drew fine. struct RGBColour { RGBColour() : r(0), g(0), b(0) {} RGBColour(unsigned char red, unsigned char green, unsigned char blue) : r(red), g(green), b(blue) {} unsigned char r; unsigned char g; unsigned char b; }; // main loading code SDLSurfaceReader* reader = new SDLSurfaceReader(m_renderer); reader->readSurface("images/grass.tga"); // new texture unsigned char* newTexture = new unsigned char[reader->m_surface->w * reader->m_surface->h * 3 * reader->m_surface->w]; for (int y = 0; y < reader->m_surface->h; y++) { for (int x = 0; x < reader->m_surface->w; x += 3) { int index = (y * reader->m_surface->w) + x; RGBColour colour = reader->getColourAt(x, y); newTexture[index] = colour.r; newTexture[index + 1] = colour.g; newTexture[index + 2] = colour.b; } } unsigned int id = m_renderer->createTextureFromData(newTexture, reader->m_surface->w, reader->m_surface->h, RGB); // functions for reading pixels RGBColour SDLSurfaceReader::getColourAt(int x, int y) { Uint32 pixel; Uint8 red, green, blue; RGBColour rgb; pixel = getPixel(m_surface, x, y); SDL_LockSurface(m_surface); SDL_GetRGB(pixel, m_surface->format, &red, &green, &blue); SDL_UnlockSurface(m_surface); rgb.r = red; rgb.b = blue; rgb.g = green; return rgb; } // this function taken from SDL documentation // http://www.libsdl.org/cgi/docwiki.cgi/Introduction_to_SDL_Video#getpixel Uint32 SDLSurfaceReader::getPixel(SDL_Surface* surface, int x, int y) { int bpp = m_surface->format->BytesPerPixel; Uint8 *p = (Uint8*)m_surface->pixels + y * m_surface->pitch + x * bpp; switch (bpp) { case 1: return *p; case 2: return *(Uint16*)p; case 3: if (SDL_BYTEORDER == SDL_BIG_ENDIAN) return p[0] << 16 | p[1] << 8 | p[2]; else return p[0] | p[1] << 8 | p[2] << 16; case 4: return *(Uint32*)p; default: return 0; } } I've been stumped at this, and I need help badly! Thanks so much for any advice.

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• How to make the Angry Birds "shot arch" dotted line? [duplicate]

  - by unexpected62

  This question already has an answer here: Show path of a body of where it should go after linear impulse is applied 2 answers I am making a game that includes 2D projectile flight paths like that of Angry Birds. Angry Birds employs the notion that a previous shot is shown with a dotted line "arch" showing the player where that last shot went. I think recording that data is simple enough once a shot is fired, but in my game, I want to show it preemptively, ie: before the shot. How would I go about calculating this dotted line? The other caveat is I have wind in my game. How can you determine a projectile preemptively when wind will affect it too? This seems like a pretty tough problem. My wind right now just applies a constant force every step of animation in the direction of the wind flow. I'm using Box2D and AndEngine if it matters.

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• Directx and Open Libraries list? [closed]

  - by OVERTONE

  I've just been looking for comparissons between open and proprietary frameworks and libraries. More so just to get an idea of what exists than how they compare. For example: We have DirectX (graphics) and its open counterpart OpenGL DirectX (sound) and OpenAL But there are other DirectX libraries that I can't find open alternatives to such as DirectInput DXGI Direct2D DirectWrite Doe's anyone have any list's or Comparisons between Directx and their open counterparts?

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• Tools for creating assets? [closed]

  - by Agent_9191

  There are similar questions about finding existing resources that are free for use (free sprites/images, music, sound), but I'm interested in creating the resources myself. What tools do you use for asset creation/modification? Please only put one tool per answer. Also try to include the following information: Product Name Link to website Type of assets is can create (2D images, 3D images, audio, etc) OS(s) supported Cost License (if free/open source) General summary

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• Incorrect lighting results with deferred rendering

  - by Lasse

  I am trying to render a light-pass to a texture which I will later apply on the scene. But I seem to calculate the light position wrong. I am working on view-space. In the image above, I am outputting the attenuation of a point light which is currently covering the whole screen. The light is at 0,10,0 position, and I transform it to view-space first: Vector4 pos; Vector4 tmp = new Vector4 (light.Position, 1); // Transform light position for shader Vector4.Transform (ref tmp, ref Camera.ViewMatrix, out pos); shader.SendUniform ("LightViewPosition", ref pos); Now to me that does not look as it should. What I think it should look like is that the white area should be on the center of the scene. The camera is at the corner of the scene, and it seems as if the light would move along with the camera. Here's the fragment shader code: void main(){ // default black color vec3 color = vec3(0); // Pixel coordinates on screen without depth vec2 PixelCoordinates = gl_FragCoord.xy / ScreenSize; // Get pixel position using depth from texture vec4 depthtexel = texture( DepthTexture, PixelCoordinates ); float depthSample = unpack_depth(depthtexel); // Get pixel coordinates on camera-space by multiplying the // coordinate on screen-space by inverse projection matrix vec4 world = (ImP * RemapMatrix * vec4(PixelCoordinates, depthSample, 1.0)); // Undo the perspective calculations vec3 pixelPosition = (world.xyz / world.w) * 3; // How far the light should reach from it's point of origin float lightReach = LightColor.a / 2; // Vector in between light and pixel vec3 lightDir = (LightViewPosition.xyz - pixelPosition); float lightDistance = length(lightDir); vec3 lightDirN = normalize(lightDir); // Discard pixels too far from light source //if(lightReach < lightDistance) discard; // Get normal from texture vec3 normal = normalize((texture( NormalTexture, PixelCoordinates ).xyz * 2) - 1); // Half vector between the light direction and eye, used for specular component vec3 halfVector = normalize(lightDirN + normalize(-pixelPosition)); // Dot product of normal and light direction float NdotL = dot(normal, lightDirN); float attenuation = pow(lightReach / lightDistance, LightFalloff); // If pixel is lit by the light if(NdotL > 0) { // I have moved stuff from here to above so I can debug them. // Diffuse light color color += LightColor.rgb * NdotL * attenuation; // Specular light color color += LightColor.xyz * pow(max(dot(halfVector, normal), 0.0), 4.0) * attenuation; } RT0 = vec4(color, 1); //RT0 = vec4(pixelPosition, 1); //RT0 = vec4(depthSample, depthSample, depthSample, 1); //RT0 = vec4(NdotL, NdotL, NdotL, 1); RT0 = vec4(attenuation, attenuation, attenuation, 1); //RT0 = vec4(lightReach, lightReach, lightReach, 1); //RT0 = depthtexel; //RT0 = 100 / vec4(lightDistance, lightDistance, lightDistance, 1); //RT0 = vec4(lightDirN, 1); //RT0 = vec4(halfVector, 1); //RT0 = vec4(LightColor.xyz,1); //RT0 = vec4(LightViewPosition.xyz/100, 1); //RT0 = vec4(LightPosition.xyz, 1); //RT0 = vec4(normal,1); } What am I doing wrong here?

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• Is there a good way to get pixel-perfect collision detection in XNA?

  - by ashes999

  Is there a well-known way (or perhaps reusable bit of code) for pixel-perfect collision detection in XNA? I assume this would also use polygons (boxes/triangles/circles) for a first-pass, quick-test for collisions, and if that test indicated a collision, it would then search for a per-pixel collision. This can be complicated, because we have to account for scale, rotation, and transparency. WARNING: If you're using the sample code from the link from the answer below, be aware that the scaling of the matrix is commented out for good reason. You don't need to uncomment it out to get scaling to work.

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• Drawing different per-pixel data on the screen

  - by Amir Eldor

  I want to draw different per-pixel data on the screen, where each pixel has a specific value according to my needs. An example may be a random noise pattern where each pixel is randomly generated. I'm not sure what is the correct and fastest way to do this. Locking a texture/surface and manipulating the raw pixel data? How is this done in modern graphics programming? I'm currently trying to do this in Pygame but realized I will face the same problem if I go for C/SDL or OpenGL/DirectX.

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• AndEngine Box2d game

  - by OneMoreVladimir

  I'm developing a 2d survival shooter using Box2d extension and I've got some questions: I have two AnalogOnScreenControls. Their listeners modify both sprites and bodies. I receive TouchEventPool was exhausted and as their number grows the game crashes accidently. I've tried to put the modification of the bodies and sprites on the UpdateThread but that does not solve the problem. What could be the cause? I have a class that at the beginnig of the game loads all the textures. After I relaunch the game activity several times I receive Unable to find Phys Addr for and "green color" interface. But that doesn't happen if I clear the memory manually through the Task Manager before relaunch What could be the cause? I unload my atlas at the end of the game. The game sometimes crashes at start with NullPointerException in onResumeGame. The solution suggested is to set android:configChanges="orientation|screenSize" but my device is API 10 so it doesn't have screenSize property and orientation only does not seem to help, because the game starts in portrait mode at times (though landscape is set in the code)

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• Switching between levels, re-initialize existing structure or create new one?

  - by Martino Wullems

  This is something I've been wondering for quite a while. When building games that exist out of multiple levels (platformers, shmups etc) what is the prefered method to switch between the levels? Let's say we have a level class that does the following: Load data for the level design (tiles), enemies, graphics etc. Setup all these elements in their appriopate locations and display them Start physics and game logic I'm stuck between the following 2 methods: 1: Throw away everything in the level class and make a new one, we have to load an entirely new level anyway! 2: pause the game logic and physics, unload all currents assets, then re-initialize those components with the level data for the new level. They both have their pros and cons. Method 1 is alot easier and seems to make sense since we have to redo everything anyway. But method 2 allows you to re-use exisiting elements which might save resources and allows for a smoother transfer to the new level.

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• How to create a reasonably sized urban area manually but efficiently

  - by Overv

  I have a game concept that only really works in an urban area that is of reasonable scale and diversity. In terms of what it should look like, think GTA, in terms of the size think more like a small neighbourhood with residents and a few local shops, perhaps a supermarket. I'm mostly experienced in programming and not at all with modelling, texturing or drawing, but I've found that SketchUp allows me to design interesting looking buildings that I model after real world buildings in my own neighbourhood. Designing these buildings and other objects can take from a few tens of minutes to a few hours. My question is: what is the best approach for a one man army like me who does manage to model buildings to create an interesting city environment in a reasonable amount of time? My game will not be based on procedural generation, the environment will actually be modelled like GTA cities.

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• Are there any preexisting maps for a Minecraft-like level I could use in my engine?

  - by Rishav Sharan

  I am working on a tiny cube-based engine like Minecraft. I was wondering if there is a way for me to get large blocky terrain in a text format that I can use for rendering on my engine? I don't want to start on procedural generation now, I just want a resource where I can get the coord list for a pretty looking terrain. Alternatively, is it possible for me to parse the Minecraft world files and use that data to generate terrain/buildings in my code?

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• Everything "invisible" when launching map from launcher

  - by Predanoob

  Excuse my noobiness, but I downloaded the SDK, and I tried the map Forest from within the editor and it worked fine. However if I launch it from the Launcher using the console it looks like this: http://i.stack.imgur.com/U7rPU.jpg I can use the weapons(although they are invisible), and interact with objects despite not seeing them. I also did my own map same problem. What am I doing wrong? ?(

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• Cocos2d: Moving background on update: offsett issue

  - by mm24

  working with Objective C, iOS and Cocos2d I am developing a vertical scrolling shooter game for iPhone (retina display models with 640 width x 960 height pixel resolution). My basic algorithm works as following: I create two instances of an image that has exactly 640 width x 960 height pixel of resolution, which we will call imageA and imageB I then set the two imags with exactly 480.0f of offset from each other, as the screenSize of a CCScene is set by default to 480.0f. At each update method call I move the two images by the same value. I make sure that their offsett stays to 480.0f However when running the game I see a 1 pixel height line between the two images. This literally bugs me and would like to adjust this. What am I doing wrong? This is a zoom in on the background when the "offsett line" is visible. The white line you can see divides the two background images and is not meant to exist as both images are completely black :): If I change the yPositionOfSecondElement value to 479.0f until the first loop the two images overlap correctly, but as soon as the loop starts the two images starts having an offsett of -1.0f. Here is the initialization code: -(void) init { //... screenHeight = 480.0f; yPositionOfSecondElement= screenHeight;//I tried subtracting an offsett of -1 but eventually the image would go wrong again yPositionOfFirstElement = 0.0f; loopedBackgroundImageInstanceA = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceA.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceA.position = CGPointMake(160.0f, yPositionOfFirstElement); [node addChild:loopedBackgroundImageInstanceA z:zLevelBackground]; //loopedBackgroundImageInstanceA.color= ccRED; loopedBackgroundImageInstanceB = [BackgroundLoopedImage loopImageForLevel:levelName]; loopedBackgroundImageInstanceB.anchorPoint = CGPointMake(0.5f, 0.0f); loopedBackgroundImageInstanceB.position = CGPointMake(160.0f, yPositionOfSecondElement); [node addChild:loopedBackgroundImageInstanceB z:zLevelBackground]; //.... } And here is the move code called at each update: -(void) moveBackgroundSprites:(BackgroundLoopedImage*)imageA :(BackgroundLoopedImage*)imageB :(ccTime)delta { isEligibleToMove=false; //This is done to avoid rounding errors float yStep = delta * [GameController sharedGameController].currentBackgroundSpeed; NSString* formattedNumber = [NSString stringWithFormat:@"%.02f", yStep]; yStep = atof([formattedNumber UTF8String]); //First should adjust position of images [self adjustPosition:imageA :imageB]; //The can get the actual image position CGPoint posA = imageA.position; CGPoint posB = imageB.position; //Here could verify if the checksum is equal to the required difference (should be 479.0f) if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply A"); } //At this stage can compute the hypotetical new position CGPoint newPosA = CGPointMake(posA.x, posA.y - yStep); CGPoint newPosB = CGPointMake(posB.x, posB.y - yStep); // Reposition stripes when they're out of bounds if (newPosA.y <= -yPositionOfSecondElement) { newPosA.y = yPositionOfSecondElement; [imageA shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } else if (newPosB.y <= -yPositionOfSecondElement) { newPosB.y = yPositionOfSecondElement; [imageB shuffle]; if (timeElapsed>=endTime && hasReachedEndLevel==FALSE) { hasReachedEndLevel=TRUE; shouldMoveImageEnd=TRUE; } } //Here should verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply B"); } imageA.position = newPosA; imageB.position = newPosB; //Here could verify that the check sum is equal to 479.0f if (![self verifyCheckSum:posA :posB]) { CCLOG(@"does not comply C"); } isEligibleToMove=true; } -(BOOL) verifyCheckSum:(CGPoint)posA :(CGPoint)posB { BOOL comply = false; float sum = 0.0f; if (posA.y > posB.y) { sum = posA.y - posB.y; } else if (posB.y > posA.y){ sum = posB.y - posA.y; } else{ return false; } if (sum!=yPositionOfSecondElement) { comply= false; } else{ comply=true; } return comply; } And here is what happens on the update: if(shouldMoveImageA && shouldMoveImageB) { if (isEligibleToMove) { [self moveBackgroundSprites:loopedBackgroundImageInstanceA :loopedBackgroundImageInstanceB :delta]; } Forget about shouldMoveImageA and shouldMoveImageB, this is just for when the background reaches the end of level, this works.

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• Sprite transparency not effected libGDX

  - by Aon GoltzCrank

  I am making a game using libGDX and Tween Universal Engine. My problem is as follows: I have 2 screens so fars, a splash screen with the logo, and a second one which is the main menu. In the splash screen I use a SpriteBatch and a Sprite with the Texture of the image I want (which goes through some scaling.) Now I use the Tween engine, along with a created SpriteAccessor to control the alpha of the sprite. I fade the picture in, then fade it out, then change it to the next screen. In the next screen I have a single sprite, and a single, 3 slot, sprite array. In this screen I also use the tween engine, I fade the single sprite into the screen (it's the background image) then I try to, using the same method, (Tween.to) to change the alpah of the sprite array (each sprite by itself.), I first set it to 0 using Tween.set, then using the method I change it. This didn't work, after some tests I tried setting the alpha of a single sprite from the array to 0, and that didn't work. It's like the program is ignoring the alpha value, I even printed out the alpha value, it saying 0, but the sprite is visible. How can I fix this, or why might it be caused?

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• How can I achieve strong typing with a component messaging system?

  - by Vaughan Hilts

  I'm looking at implementing a messaging system in my entity component system. I've deduced that I can use an event / queue for passing messages, but right now, I just use a generic object and cast out the data I want. I also considered using a dictionary. I see a lot of information on this, but they all involve a lot of casting and guessing. Is there any way to do this elegantly and keep strong typing on my messages?

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• Question about JPanel "transition" for Java Swing

  - by user16778

  I want to make like a sort of main menu (in GUI). When the user clicks the start button, the screen transition into another "screen" (JPanel). This image will make it easier to understand. http://i.imgur.com/Cfdry.png Currently, I have a MainMenu extends JPanel and that gets added into a driver class with a JFrame. I can't figure how to switch to another class like Game extends JPanel. So when the user clicks the start button in MainMenu, I want it to somehow hide itself and the Game to show itself. Thanks.

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• Why is chunk size often a power of two?

  - by danijar

  There are many Minecraft clones out there and I am working on my own implementation. A principle of terrain rendering is tiling the whole world in fixed size chunks to reduce the effort of localized changes. In Minecraft the chunk size is 16 x 16 x 256 as far as I now. And in clones I also always saw chunk sizes of a power of the number 2. Is there any reason for that, maybe performance or memory related? I know that powers of 2 play a special role in binary computers but what has that to do with the chunk size?

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• Beginner question about vertex arrays in OpenGL

  - by MrDatabase

  Is there a special order in which vertices are entered into a vertex array? Currently I'm drawing single textures like this: glBindTexture(GL_TEXTURE_2D, texName); glVertexPointer(2, GL_FLOAT, 0, vertices); glTexCoordPointer(2, GL_FLOAT, 0, coordinates); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); where vertices has four "xy pairs". This is working fine. As a test I doubled the sizes of the vertices and coordinates arrays and changed the last line above to: glDrawArrays(GL_TRIANGLE_STRIP, 0, 8); since vertices now contains eight "xy pairs". I do see two textures (the second is intentionally offset from the first). However the textures are now distorted. I've tried passing GL_TRIANGLES to glDrawArrays instead of GL_TRIANGLE_STRIP but this doesn't work either. I'm so new to OpenGL that I thought it's best to just ask here :-) Cheers!

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• Material, Pass, Technique and shaders

  - by Papi75

  I'm trying to make a clean and advanced Material class for the rendering of my game, here is my architecture: class Material { void sendToShader() { program->sendUniform( nameInShader, valueInMaterialOrOther ); } private: Blend blendmode; ///< Alpha, Add, Multiply, … Color ambient; Color diffuse; Color specular; DrawingMode drawingMode; // Line Triangles, … Program* program; std::map<string, TexturePacket> textures; // List of textures with TexturePacket = { Texture*, vec2 offset, vec2 scale} }; How can I handle the link between the Shader and the Material? (sendToShader method) If the user want to send additionals informations to the shader (like time elapsed), how can I allow that? (User can't edit Material class) Thanks!

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• Which Graphics/Geometry abstraction to choose?

  - by Robz

  I've been thinking about the design for a browser app on the HTML5 canvas that simulates a 2D robot zooming around, sensing the world around it. I decided to do this from scratch just for fun. I need shapes, like polygons, circles, and lines in order to model the robot and the world it lives in. These shapes need to be drawn with different appearance attributes, like border/fill style/width/color. I also need to have geometry functions to detect intersections and containment for the robot's sensors and so that the robot doesn't go inside stuff. One idea for functions is to have two totally separate libraries, one to implement graphics (like drawShape(context, shape)) and one for geometry operations (like shapeIntersectsShape(shape1, shape2)). Or, in a more object-oriented approach, the shape objects themselves could implement methods to do their own graphics (shape.draw(context)) and geometry operations (shape1.intersects(shape2)). Then there is the data itself: whether the data to draw a shape and the data to do geometric operations on that shape should be encapsulated within the same object, or be separate structures (where one would contain the other, or both be contained inside another structure). How do existing applications that do graphics/geometry stuff deal with this? Is there one model that is best, or is each good for certain applications? Should the fact that I'm using Javascript instead of a more classical language change how I approach the design?

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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