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  • Cropping a line (laser beam) in XNA

    - by electroflame
    I have a laser sprite that I wish to crop. I want to crop it so when it collides with an item, I can calculate the distance between the starting point, and the ending point, and only draw that. This eliminates the "overdraw" of a laser drawing past an item. Essentially, I'm trying to crop a line, but also keep that line "attached" to the nose of my ship. The line should not be drawn past the nose of my ship, that should be the starting point. There is no rotation to worry about. Currently, I thought that doing this through SpriteBatch would be best. This is my current Spritebatch code: spriteBatch.Draw(Laser.sprite, new Rectangle((int)Laser.position.X, (int)Laser.position.Y, Laser.sprite.Width, LaserHeight), new Rectangle(0, 0, (int)(Laser.sprite.Width), LaserHeight), new Color(255, 255, 255, (byte)MathHelper.Clamp(Laser.Alpha, 0, 255)), Laser.rotation, new Vector2(Laser.sprite.Width/2, LaserHeight/2), SpriteEffects.None, 0); But this doesn't quite work. It does only draw part of the sprite, but when LaserHeight is incremented, it lengthens the line in both ways! I believe this is due to some stupid error on my part with the Origin of the draw. Quick recap: I need to have my laser sprite drawn with the bottom of it at the nose of my ship, and then use LaserHeight to crop the image so only part of it is drawn. I have a feeling my explanation is a bit...lacking. So if you require more information, please say so and I will try to provide more information. Thanks in advance!

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  • ray collision with rectangle and floating point accuracy

    - by phq
    I'm trying to solve a problem with a ray bouncing on a box. Actually it is a sphere but for simplicity the box dimensions are expanded by the sphere radius when doing the collision test making the sphere a single ray. It is done by projecting the ray onto all faces of the box and pick the one that is closest. However because I'm using floating point variables I fear that the projected point onto the surface might be interpreted as being below in the next iteration, also I will later allow the sphere to move which might make that scenario more likely. Also the bounce coefficient might be as low as zero, making the sphere continue along the surface. So my naive solution is to project not only forwards but backwards to catch those cases. That is where I got into problems shown in the figure: In the first iteration the first black arrow is calculated and we end up at a point on the surface of the box. In the second iteration the "back projection" hits the other surface making the second black arrow bounce on the wrong surface. If there are several boxes close to each other this has further consequences making the sphere fall through them all. So my main question is how to handle possible floating point accuracy when placing the sphere on the box surface so it does not fall through. In writing this question I got the idea to have a threshold to only accept back projections a certain amount much smaller than the box but larger than the possible accuracy limitation, this would only cause the "false" back projection when the sphere hit the box on an edge which would appear naturally. To clarify my original approach, the arrows shown in the image is not only the path the sphere travels but is also representing a single time step in the simulation. In reality the time step is much smaller about 0.05 of the box size. The path traveled is projected onto possible sides to avoid traveling past a thinner object at higher speeds. In normal situations the floating point accuracy is not an issue but there are two situations where I have the concern. When the new position at the end of the time step is located very close to the surface, very unlikely though. When using a bounce factor of 0, here it happens every time the sphere hit a box. To add some loss of accuracy, the motivation for my concern, is that the sphere and box are in different coordinate systems and thus the sphere location is transformed for every test. This last one is why I'm not willing to stand on luck that one floating point value lying on top of the box always will be interpreted the same. I did not know voronoi regions by name, but looking at it I'm not sure how it would be used in a projection scenario that I'm using here.

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  • How can I import models from Blender into jMonkeyEngine?

    - by Nathan Sabruka
    I have some blender model files (Blender version 2.6) which I would like to use with the jMonkeyEngine SDK. However, when I use Blender's native .obj exporter, I can't import it in jMonkeyEngine (the model simply fails to import or looks messed up). I've tried importing .obj files or .blend files directly into the jMonkeyEngine SDK to no avail. I've also tried to use various OGRE exporters to export .scene and .material files, but only the .scene file is created. Is there a simple way to simply export files from Blender into the jMonkeyEngine SDK? EDIT: I seem to have found something in Blender. When I go under addons, there's a warning in the OGRE exporter; "'.mesh' output requires OgreCommandLineTools". However, I have already installed those tools under the C drive. Has anyone else encountered this issue?

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  • How can I implement 2D cel shading in XNA?

    - by Artii
    So I was just wondering on how to give a scene I am rendering a hand drawn look (like say Crayon Physics). I don't really want to preprocess the sprites and was thinking of using a shader. Cel shading supplies the effect I want to achieve, but I am only aware of the 3D instances for it. So I wanted to ask if anyone knew a way to get this effect in 2D, or if cel shading would work just as fine on 2D scenes?

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  • Simultaneous AI in turn based games

    - by Eduard Strehlau
    I want to hack together a roguelike. Now I thought about entity and world representation and got to a quite big problem. If you want all the AI to act simultaneously you would normally(in cellular automa for examble) just copy the cell buffer and let all action of indiviual cells depend on the copy. Actions which are not valid anymore after some cell before the cell you are currently operating on changed the original enviourment(blocking the path) are just ignored or reapplied with the "current"(between turns) environment. After all cells have acted you copy the current map to the buffer again. Now for an environment with complex AI and big(datawise) entities the copying would take too long. So I thought you could put every action and entity makes into a que(make no changes to the environment) and execute the whole que after everyone took their move. Every interaction on this que are realy interacting entities, so if a entity tries to attack another entity it sends a message to it, the consequences of the attack would be visible next turn, either by just examining the entity or asking the entity for data. This would remove problems like what happens if an entity dies middle in the cue but got actions or is messaged later on(all messages would go to null, and the messages from the entity would either just be sent or deleted(haven't decided yet) But what would happen if a monster spawns a fireball which by itself tracks the player(in the same turn). Should I add the fireball to the enviourment beforehand, so make a change to the environment before executing the action list or just add the ball to the "need updated" list as a special case so it doesn't exist in the environment and still operates on it, spawing after evaluating the action list? Are there any solutions or papers on this subject which I can take a look at? EDIT: I don't need information on writing a roguelike I need information on turn based ai in respective to a complex enviourment.

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  • Low coupling and tight cohesion

    - by hidayat
    Of course it depends on the situation. But when a lower lever object or system communicate with an higher level system, should callbacks or events be preferred to keeping a pointer to higher level object? For example, we have a world class that has a member variable vector<monster> monsters. When the monster class is going to communicate with the world class, should I prefer using a callback function then or should I have a pointer to the world class inside the monster class?

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  • Producing a smooth mesh from density cloud and marching cubes

    - by Wardy
    Based on my results from this question I decided to build myself a 3D noise map containing float values in place of my existing boolean point values. The effect I'm trying to produce is something like this, rather than typical rolling hills; which should explain the "missing cubes" in the image below. If I render my density map in normal "minecraft mode" (1 block per point in the density map) varying the size of the cube based on the value in my density map (floats in the range 0 to 1) I get something like this: I'm now happy that I can produce a density map for the marching cubes algorithm (which will need a little tweaking) but for some reason when I run it through my implementation it's not producing what I expect. My problem is that I'm getting something like the first image in this answer to my previous question, when I want to achieve the effect in the second image. Upon further investigation I can't see how marching cubes does the "move vertex along the edge" type logic (i.e. the difference between the two images on my previous link). I see that it does do some interpolation, but I'm not convinced I have the correct understanding of what I think it should do, because the code in question appears to give the same result regardless of whether I use boolean or float values. I took the code from here which is a C# implementation of marching cubes, but instead of using the MarchingCubesPrimitive I modified it to accept an object of type IDrawable, containing lists for the various collections (vertices, normals, UVs, indices), the logic was otherwise untouched. My understanding is that given a very low isovalue the accuracy level of the surface being rendered should increase, so in short "less 45 degree slows more rolling hills" type mesh output. However this isn't what I'm seeing. Have I missed something or is the implementation flawed and need to be fixed? EDIT: A little more detail on what I am seeing when I "marching cube" the data. Ok so firstly, ignore the fact that the meshes created by the chunks don't "connect" (i'll probably raise another question about this later). Then look at the shaping of the island, it's too ... square, from the voxels rendered as boxes you get the impression there's a clean soft gradual hill and yet from the image there are sharp falling edges even in the most central areas where the gradient in the first image looks the most smooth. The data is "regenerated" each time I run this so no 2 islands come out the same, and it's purely random so not based on noise, but still, how can it look so smooth in 1 image and so not smooth in the other?

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  • Texturing a mesh generated from voxel data

    - by Minja
    I have implemented the Marching Cubes algorithm to display an isosurface based on voxel data. Currently, it is displayed with triplanar texturing. I'm working with unity, so I have a material with the triplanar shader attached. Now, the whole isosurface is rendered using this material. And thats my problem: I want the texture to represent the voxel data. I'm storing a material value for every point in the grid, and based on this value, I want the texture of the isosurface to change. Sadly, I have no clue how to do this. So if the voxel is sand, I want sand to be displayed; if it's stone, then there should be stone. Right now, everything is displayed as sand. Thanks in advance!

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  • How to make unit selection circles merge?

    - by MaT
    I would like to know how to make this effect of merged circle selection. Here are images to illustrate: Basically I'm looking for this effect: How the merge effect of the circles can be achieved ? I didn't found any explanation concerning this effect. I know that to project those texture I can develop a decal system but I don't know how to create the merging effect. If possible, I'm looking for purely shaders solution.

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  • My grid based collision detection is slow

    - by Fibericon
    Something about my implementation of a basic 2x4 grid for collision detection is slow - so slow in fact, that it's actually faster to simply check every bullet from every enemy to see if the BoundingSphere intersects with that of my ship. It becomes noticeably slow when I have approximately 1000 bullets on the screen (36 enemies shooting 3 bullets every .5 seconds). By commenting it out bit by bit, I've determined that the code used to add them to the grid is what's slowest. Here's how I add them to the grid: for (int i = 0; i < enemy[x].gun.NumBullets; i++) { if (enemy[x].gun.bulletList[i].isActive) { enemy[x].gun.bulletList[i].Update(timeDelta); int bulletPosition = 0; if (enemy[x].gun.bulletList[i].position.Y < 0) { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450); } else { bulletPosition = (int)Math.Floor((enemy[x].gun.bulletList[i].position.X + 900) / 450) + 4; } GridItem bulletItem = new GridItem(); bulletItem.index = i; bulletItem.type = 5; bulletItem.parentIndex = x; if (bulletPosition > -1 && bulletPosition < 8) { if (!grid[bulletPosition].Contains(bulletItem)) { for (int j = 0; j < grid.Length; j++) { grid[j].Remove(bulletItem); } grid[bulletPosition].Add(bulletItem); } } } } And here's how I check if it collides with the ship: if (ship.isActive && !ship.invincible) { BoundingSphere shipSphere = new BoundingSphere( ship.Position, ship.Model.Meshes[0].BoundingSphere.Radius * 9.0f); for (int i = 0; i < grid.Length; i++) { if (grid[i].Contains(shipItem)) { for (int j = 0; j < grid[i].Count; j++) { //Other collision types omitted else if (grid[i][j].type == 5) { if (enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive) { BoundingSphere bulletSphere = new BoundingSphere(enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].position, enemy[grid[i][j].parentIndex].gun.bulletModel.Meshes[0].BoundingSphere.Radius); if (shipSphere.Intersects(bulletSphere)) { ship.health -= enemy[grid[i][j].parentIndex].gun.damage; enemy[grid[i][j].parentIndex].gun.bulletList[grid[i][j].index].isActive = false; grid[i].RemoveAt(j); break; //no need to check other bullets } } else { grid[i].RemoveAt(j); } } What am I doing wrong here? I thought a grid implementation would be faster than checking each one.

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  • Problems Rendering Text in OpenGL Using FreeType

    - by Sean M.
    I've been following both the FreeType2 tutorial and the WikiBooks tuorial, trying to combine things from them both in order to load and render fonts using the FreeType library. I used the font loading code from the FreeType2 tutorial and tried to implement the rendering code from the wikibooks tutorial (tried being the keyword as I'm still trying to learn model OpenGL, I'm using 3.2). Everything loads correctly and I have the shader program to render the text with working, but I can't get the text to render. I'm 99% sure that it has something to do with how I cam passing data to the shader, or how I set up the screen. These are the code segments that handle OpenGL initialization, as well as Font initialization and rendering: //Init glfw if (!glfwInit()) { fprintf(stderr, "GLFW Initialization has failed!\n"); exit(EXIT_FAILURE); } printf("GLFW Initialized.\n"); //Process the command line arguments processCmdArgs(argc, argv); //Create the window glfwWindowHint(GLFW_SAMPLES, g_aaSamples); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2); g_mainWindow = glfwCreateWindow(g_screenWidth, g_screenHeight, "Voxel Shipyard", g_fullScreen ? glfwGetPrimaryMonitor() : nullptr, nullptr); if (!g_mainWindow) { fprintf(stderr, "Could not create GLFW window!\n"); closeOGL(); exit(EXIT_FAILURE); } glfwMakeContextCurrent(g_mainWindow); printf("Window and OpenGL rendering context created.\n"); glClearColor(0.2f, 0.2f, 0.2f, 1.0f); //Are these necessary for Modern OpenGL (3.0+)? glViewport(0, 0, g_screenWidth, g_screenHeight); glOrtho(0, g_screenWidth, g_screenHeight, 0, -1, 1); //Init glew int err = glewInit(); if (err != GLEW_OK) { fprintf(stderr, "GLEW initialization failed!\n"); fprintf(stderr, "%s\n", glewGetErrorString(err)); closeOGL(); exit(EXIT_FAILURE); } printf("GLEW initialized.\n"); Here is the font file (it's slightly too big to post): CFont.h/CFont.cpp Here is the solution zipped up: [solution] (https://dl.dropboxusercontent.com/u/36062916/VoxelShipyard.zip), if anyone feels they need the entire solution. If anyone could take a look at the code, it would be greatly appreciated. Also if someone has a tutorial that is a little more user friendly, that would also be appreciated. Thanks.

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  • libgdx intersection problem between rectangle and circle

    - by Chris
    My collision detection in libgdx is somehow buggy. player.png is 20*80px and ball.png 25*25px. Code: @Override public void create() { // ... batch = new SpriteBatch(); playerTex = new Texture(Gdx.files.internal("data/player.png")); ballTex = new Texture(Gdx.files.internal("data/ball.png")); player = new Rectangle(); player.width = 20; player.height = 80; player.x = Gdx.graphics.getWidth() - player.width - 10; player.y = 300; ball = new Circle(); ball.x = Gdx.graphics.getWidth() / 2; ball.y = Gdx.graphics.getHeight() / 2; ball.radius = ballTex.getWidth() / 2; } @Override public void render() { Gdx.gl.glClearColor(1, 1, 1, 1); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); camera.update(); // draw player, ball batch.setProjectionMatrix(camera.combined); batch.begin(); batch.draw(ballTex, ball.x, ball.y); batch.draw(playerTex, player.x, player.y); batch.end(); // update player position if(Gdx.input.isKeyPressed(Keys.DOWN)) player.y -= 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.UP)) player.y += 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.LEFT)) player.x -= 250 * Gdx.graphics.getDeltaTime(); if(Gdx.input.isKeyPressed(Keys.RIGHT)) player.x += 250 * Gdx.graphics.getDeltaTime(); // don't let the player leave the field if(player.y < 0) player.y = 0; if(player.y > 600 - 80) player.y = 600 - 80; // check collision if (Intersector.overlaps(ball, player)) Gdx.app.log("overlaps", "yes"); }

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  • add collision detection to sprite?

    - by xBroak
    bassically im trying to add collision detection to the sprite below, using the following: self.rect = bounds_rect collide = pygame.sprite.spritecollide(self, wall_list, False) if collide: # yes print("collide") However it seems that when the collide is triggered it continuously prints 'collide' over and over when instead i want them to simply not be able to walk through the object, any help? def update(self, time_passed): """ Update the creep. time_passed: The time passed (in ms) since the previous update. """ if self.state == Creep.ALIVE: # Maybe it's time to change the direction ? # self._change_direction(time_passed) # Make the creep point in the correct direction. # Since our direction vector is in screen coordinates # (i.e. right bottom is 1, 1), and rotate() rotates # counter-clockwise, the angle must be inverted to # work correctly. # self.image = pygame.transform.rotate( self.base_image, -self.direction.angle) # Compute and apply the displacement to the position # vector. The displacement is a vector, having the angle # of self.direction (which is normalized to not affect # the magnitude of the displacement) # displacement = vec2d( self.direction.x * self.speed * time_passed, self.direction.y * self.speed * time_passed) self.pos += displacement # When the image is rotated, its size is changed. # We must take the size into account for detecting # collisions with the walls. # self.image_w, self.image_h = self.image.get_size() global bounds_rect bounds_rect = self.field.inflate( -self.image_w, -self.image_h) if self.pos.x < bounds_rect.left: self.pos.x = bounds_rect.left self.direction.x *= -1 elif self.pos.x > bounds_rect.right: self.pos.x = bounds_rect.right self.direction.x *= -1 elif self.pos.y < bounds_rect.top: self.pos.y = bounds_rect.top self.direction.y *= -1 elif self.pos.y > bounds_rect.bottom: self.pos.y = bounds_rect.bottom self.direction.y *= -1 self.rect = bounds_rect collide = pygame.sprite.spritecollide(self, wall_list, False) if collide: # yes print("collide") elif self.state == Creep.EXPLODING: if self.explode_animation.active: self.explode_animation.update(time_passed) else: self.state = Creep.DEAD self.kill() elif self.state == Creep.DEAD: pass #------------------ PRIVATE PARTS ------------------# # States the creep can be in. # # ALIVE: The creep is roaming around the screen # EXPLODING: # The creep is now exploding, just a moment before dying. # DEAD: The creep is dead and inactive # (ALIVE, EXPLODING, DEAD) = range(3) _counter = 0 def _change_direction(self, time_passed): """ Turn by 45 degrees in a random direction once per 0.4 to 0.5 seconds. """ self._counter += time_passed if self._counter > randint(400, 500): self.direction.rotate(45 * randint(-1, 1)) self._counter = 0 def _point_is_inside(self, point): """ Is the point (given as a vec2d) inside our creep's body? """ img_point = point - vec2d( int(self.pos.x - self.image_w / 2), int(self.pos.y - self.image_h / 2)) try: pix = self.image.get_at(img_point) return pix[3] > 0 except IndexError: return False def _decrease_health(self, n): """ Decrease my health by n (or to 0, if it's currently less than n) """ self.health = max(0, self.health - n) if self.health == 0: self._explode() def _explode(self): """ Starts the explosion animation that ends the Creep's life. """ self.state = Creep.EXPLODING pos = ( self.pos.x - self.explosion_images[0].get_width() / 2, self.pos.y - self.explosion_images[0].get_height() / 2) self.explode_animation = SimpleAnimation( self.screen, pos, self.explosion_images, 100, 300) global remainingCreeps remainingCreeps-=1 if remainingCreeps == 0: print("all dead")

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  • GLSL, is it possible to offsetting vertices based on height map colour?

    - by Rob
    I am attempting to generate some terrain based upon a heightmap. I have generated a 32 x 32 grid and a corresponding height map - In my vertex shader I am trying to offset the position of the Y axis based upon the colour of the heightmap, white vertices being higher than black ones. //Vertex Shader Code #version 330 uniform mat4 modelMatrix; uniform mat4 viewMatrix; uniform mat4 projectionMatrix; uniform sampler2D heightmap; layout (location=0) in vec4 vertexPos; layout (location=1) in vec4 vertexColour; layout (location=3) in vec2 vertexTextureCoord; layout (location=4) in float offset; out vec4 fragCol; out vec4 fragPos; out vec2 fragTex; void main() { // Retreive the current pixel's colour vec4 hmColour = texture(heightmap,vertexTextureCoord); // Offset the y position by the value of current texel's colour value ? vec4 offset = vec4(vertexPos.x , vertexPos.y + hmColour.r, vertexPos.z , 1.0); // Final Position gl_Position = projectionMatrix * viewMatrix * modelMatrix * offset; // Data sent to Fragment Shader. fragCol = vertexColour; fragPos = vertexPos; fragTex = vertexTextureCoord; } However the code I have produced only creates a grid with none of the y vertices higher than any others.

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  • Early Z culling - Ogre

    - by teodron
    This question is concerned with how one can enable this "pixel filter" to work within an Ogre based app. Simply put, one can write two passes, the first without writing any colour values to the frame buffer lighting off colour_write off shading flat The second pass is the one that employs heavy pixel shader computations, hence it would be really nice to get rid of those hidden surface patches and not process them pixel-wise. This approach works, except for one thing: objects with alpha, such as billboard trees suffer in a peculiar way - from one side, they seem to capture the sky/background within their alpha region and ignore other trees/houses behind them, while viewed from the other side, they exhibit the desired behavior. To tackle the issue, I thought I could write a custom vertex shader in the first pass and offset the projected Z component of the vertex a little further away from its actual position, so that in the second pass there is a need to recompute correctly the pixels of the objects closest to the camera. This doesn't work at all, all surfaces are processed in the pixel shader and there is no performance gain. So, if anyone has done a similar trick with Ogre and alpha objects, kindly please help.

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  • Greiner-Hormann clipping problem

    - by Belgin
    I have a set of planar polygons in 3D space defined by their vertices in counterclockwise order. Let's define the 'positive face' as being the face of the 3D polygon such as when observed, the vertices appear in counterclockwise order, and the 'negative face', the face which when observed, the vertices appear in clockwise order. I'm doing perspective projection of the set of polygons onto a projection polygon defined by the points in this order: (0, h, 0), (0, 0, 0), (w, 0, 0), and (w, h, 0), where w and h are strictly positive integers. The positive face of this projection polygon is oriented towards positive Z, and the camera point is somewhere at (0, 0, d), where d is a strictly negative number. In order to 'clip' the projected polygons into the projection polygon, I'm applying the Greiner-Hormann (PDF) clipping algorithm, which requires that the clipper and the to-be-clipped polygons be in the same order (i.e. clockwise or counterclockwise). My question is the following: How can I determine whether the projected face of the 3D polygon is the negative or the positive one? Meaning, how do I find out if I have to work with the vertices in normal or inverted order for the algorithm to work? I noticed that only if the 3D polygon is facing the projection polygon with its negative face, both of them are in the same order (counterclockwise), otherwise, a modification needs to be done. Here is a picture (PNG) that illustrates this. Note that the planes described by the polygon from the set and the projection polygon may not always be parallel.

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  • HLSL Pixel Shader that does palette swap

    - by derrace
    I have implemented a simple pixel shader which can replace a particular colour in a sprite with another colour. It looks something like this: sampler input : register(s0); float4 PixelShaderFunction(float2 coords: TEXCOORD0) : COLOR0 { float4 colour = tex2D(input, coords); if(colour.r == sourceColours[0].r && colour.g == sourceColours[0].g && colour.b == sourceColours[0].b) return targetColours[0]; return colour; } What I would like to do is have the function take in 2 textures, a default table, and a lookup table (both same dimensions). Grab the current pixel, and find the location XY (coords) of the matching RGB in the default table, and then substitute it with the colour found in the lookup table at XY. I have figured how to pass the Textures from C# into the function, but I am not sure how to find the coords in the default table by matching the colour. Could someone kindly assist? Thanks in advance.

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  • Basic tutorial/introduction for 3d matrices, idealy in c++, without openGl or directX

    - by René Nyffenegger
    I am wondering if there is a simple tutorial that covers the basics of how to initialize rotation, translation and projection matrices, and how to multiply them, and how to get the screen coordinates afterwards for a 3d point. Idealy, the tutorial comes with compilable code and is not dependent on any 3rd party library. Searching the internet, I found lots of tutorials, so this is not the problem. Yet, it seemed all of these either covered openGl or directX, or they were theoretical in nature.

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  • How to change speed without changing path travelled?

    - by Ben Williams
    I have a ball which is being thrown from one side of a 2D space to the other. The formula I am using for calculating the ball's position at any one point in time is: x = x0 + vx0*t y = y0 + vy0*t - 0.5*g*t*t where g is gravity, t is time, x0 is the initial x position, vx0 is the initial x velocity. What I would like to do is change the speed of this ball, without changing how far it travels. Let's say the ball starts in the lower left corner, moves upwards and rightwards in an arc, and finishes in the lower right corner, and this takes 5s. What I would like to be able to do is change this so it takes 10s or 20s, but the ball still follows the same curve and finishes in the same position. How can I achieve this? All I can think of is manipulating t but I don't think that's a good idea. I'm sure it's something simple, but my maths is pretty shaky.

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  • Pathfinding and BSP with Box2D

    - by Amplify91
    I'm looking into implementing AI in my 2D side-scrolling platformer, and I'm looking into using algorithms such as A*. For many kinds of pathfinding, we need some sort of grid or systems of nodes or polygon areas. My problem is that I am using Box2d for physics and I am not sure how best to create a structure that my AI can use besides placing individual nodes manually (something I really want to avoid) and using some sort of steering behavior. My level design is tile-based with each tile being about half of the height/width of my main character. The tiles are not all square (some are sloped). I'd like to have a system that can see what the terrain looks like for pathfinding and also keep track of the positions of other actors such as enemies. I'd like to avoid directly placing any nodes into my level design except for possible endpoints or goals. This question is related: How do you do AI path following within a 2d physics engine like farseer/box2d?, but it doesn't specify what kind of structure I could use instead of a list of nodes. I'm looking for some kind of grid or type of BSP that I can query for algorithms like A*.

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  • What could cause a pixel shader to paint outside the lines of the vertex shader output?

    - by Rei Miyasaka
    From what I understand, the pixels that a pixel shader operates on are specified implicitly by the SV_POSITION output (in DirectX) of the vertex shader. What then could cause a pixel shader to render in the middle of nowhere? I used the new Visual Studio 2012 graphics debugger to visualize my vertex and pixel shader output. This is the output from a DrawIndexed() call that draws a cube: The pink part is the rendered output of the pixel shader, which takes the cube on its left as its input. The vertex shader code: cbuffer Buf { float4x4 final; }; struct In { float4 pos:POSITION; float3 norm:NORMAL; float2 texuv:TEXCOORD; }; struct Out { float4 col:COLOR; float2 tex:TEXCOORD; float4 pos:SV_POSITION; }; Out main(In input) { Out output; output.pos = mul(input.pos, final); output.col = float4(1.0f, 0.5f, 0.5f, 1.0f); output.tex = input.texuv; return output; } And the pixel shader: struct In { float4 col:COLOR; float2 tex:TEXCOORD; float4 pos:SV_POSITION; }; float4 main(In input) : SV_TARGET { return input.col; } The raster stage is the only thing between the vertex shader and the pixel shader, so my suspicion is that it's some raster stage settings. But the raster stage shouldn't change the shape of the vertex shader output so drastically, should it?

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  • If I use my own normal values, should I turn off winding order culling?

    - by Phil
    I've discovered that I managed to program a series of boxes with indexed vertices in such a way that every other triangle (Half of each face) has a backwards winding order. As a result, XNA is culling half of them. However, my Vertex objects contain normal data that I have explicitly set, and I am going to implement my own backface culling shortly to reduce the size of the VertexBuffer. Should I turn off winding order culling and manage it myself, or should I make sure the winding order is consistent and let XNA handle it?

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  • Missing z-axis rotation for transforming between two vectors

    - by Steve Baughman
    I'm trying to rotate a cube so that it's facing up, but am getting hung up on the final implementation details. It now reliably will rotate the x,y axis to the correct side, but the z-axis is never rotating (See photos of before and after rotation). When I'm using the code below I always get '0' for my rotationVector.z. What am I missing here? // Define lookAt vector lookAtVector = GLKVector3Make(0,0,1); // Define axes vectors axes[0] = GLKVector3Make(0,0,1); axes[1] = GLKVector3Make(-1,0,0); axes[2] = GLKVector3Make(0,1,0); axes[3] = GLKVector3Make(1,0,0); axes[4] = GLKVector3Make(0,-1,0); axes[5] = GLKVector3Make(0,0,-1); CGFloat highest_dot = -1.0; GLKVector3 closest_axis; for(int i = 0; i < 6; i++) { // multiply cube's axes by existing matrix GLKVector3 axis = GLKMatrix4MultiplyVector3(matrix, axes[i]); CGFloat dot = GLKVector3DotProduct(axis, lookAtVector); if(dot > highest_dot) { closest_axis = axis; highest_dot = dot; } } GLKVector3 rotationVector = GLKVector3CrossProduct(closest_axis, lookAtVector); // Get angle between vectors CGFloat angle = atan2(GLKVector3Length(rotationVector), GLKVector3DotProduct(closest_axis, lookAtVector)); // normalize the rotation vector rotationVector = GLKVector3Normalize(rotationVector); // Create transform CATransform3D rotationTransform = CATransform3DMakeRotation(angle, rotationVector.x, rotationVector.y, rotationVector.z); // add rotation transform to existing transformation baseTransform = CATransform3DConcat(baseTransform, rotationTransform); return baseTransform; Before 3d Rotation After 3d Rotation Implementation based on this post

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  • tunnel effect cocos2d

    - by samfisher
    I am looking to create a similar tunnel effect in COCOS2D (iOS). Could anyone suggest any pointers? ref Video 1 ref Video 2 Till now I have tried with several ring shape sprites with decreasing scale and positioned center to a same point and keeping Z decreasing as well for each smaller sprite. With that, animating it with CCScaleTo and changing the size to 2.0 with animation duration but it does not come anyway near to the tunnel effect shown in the reference. Thanks, sam

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  • Center directional light shadow to the cameras eye

    - by Caesar
    I'm currently drawing my directional light shadow using this view and projection: XMFLOAT3 dir((float)pitch, (float)yaw, (float)roll); XMFLOAT3 center(0.0f, 0.0f, 0.0f); XMVECTOR lightDir = XMLoadFloat3(&dir); XMVECTOR lightPos = radius * lightDir; XMVECTOR targetPos = XMLoadFloat3(&center); XMVECTOR up = XMVectorSet(0.0f, 1.0f, 0.0f, 0.0f); XMMATRIX V = XMMatrixLookAtLH(lightPos, targetPos, up); // This is the view // Transform bounding sphere to light space. XMFLOAT3 sphereCenterLS; XMStoreFloat3(&sphereCenterLS, XMVector3TransformCoord(targetPos, V)); // Ortho frustum in light space encloses scene. float l = sphereCenterLS.x - radius; float b = sphereCenterLS.y - radius; float n = sphereCenterLS.z - radius; float r = sphereCenterLS.x + radius; float t = sphereCenterLS.y + radius; float f = sphereCenterLS.z + radius; XMMATRIX P = XMMatrixOrthographicOffCenterLH(l, r, b, t, n, f); // This is the projection Which works prefect if the center of my scene is at 0.0, 0.0, 0.0. What I would like to do is move the center of the scene relative to the cameras position. How can I do that?

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