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• Collision Resolution

  - by ultifinitus

  Hey all, I'm making a simple side-scrolling game, and I would appreciate some input! My collision detection system is a simple bounding box detection, so it's really easy to implement. However my collision resolution is ridiculous! Currently I have a little formula like this: if (colliding(firstObject,secondObject)) firstObject.resolve_collision(yAxisOffset); if (colliding(firstObject,secondObject)) firstObject.resolve_collision(xAxisOffset); where yAxisOffset is only set if the first object's previous y position was outside the second object's collision frame, respectively xAxisOffset as well. Now this is working great, in general. However there is a single problem. When I have a stack of objects and I push the first object against that stack, the first object get's "stuck," on the stack. What's I think is happening is the object's collision system checks and resolves for collisions based on creation time, so If I check one axis, then the other, the object will "sink" object directly along the checking axis. This sinking action causes the collision detection routine to think there's a gap between our position and the other object's position, and when I finally check the object that I've already sunk into, my object's position is resolved to it's original position... All this is great, and I'm sure if I bang my head against a wall long enough i'll come up with a working algorithm, but I'd rather not =). So what in the heck do you think I should do? How could I change my collision resolution system to fix this? Here's the program (temporary link, not sure how long it'll last) (notes: arrow keys to navigate, click to drop block, x to jump) I'd appreciate any help you can offer!

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• Picture rendered from above and below using an Orthographic camera do not match

  - by Roy T.

  I'm using an orthographic camera to render slices of a model (in order to voxelize it). I render each slice both from above and below in order to determine what is inside each slice. I am using an orthographic camera The model I render is a simple 'T' shape constructed from two cubes. The cubes have the same dimensions and have the same Y (height) coordinate. See figure 1 for a render of it in Blender. I render this model once directly from above and once directly from below. My expectation was that I would get exactly the same image (except for mirroring over the y-axis). However when I render using a very low resolution render target (25x25) the position (in pixels) of the 'T' is different when rendered from above as opposed to rendered from below. See figure 2 and 3. The pink blocks are not part of the original rendering but I've added them so you can easily count/see the differences. Figure 2: the T rendered from above Figure 3: the T rendered from below This is probably due to what I've read about pixel and texel coordinates which might be biased to the top-left as seen from the camera. Since I'm using the same 'up' vector for both of my camera's my bias only shows on the x-axis. I've tried to change the position of the camera and it's look-at by, what I thought, should be half a pixel. I've tried both shifting a single camera and shifting both cameras and while I see some effect I am not able to get a pixel-by-pixel perfect copy from both camera's. Here I initialize the camera and compute, what I believe to be, half pixel. boundsDimX and boundsDimZ is a slightly enlarged bounding box around the model which I also use as the width and height of the view volume of the orthographic camera. Matrix projection = Matrix.CreateOrthographic(boundsDimX, boundsDimZ, 0.5f, sliceHeight + 0.5f); Vector3 halfPixel = new Vector3(boundsDimX / (float)renderTarget.Width, 0, boundsDimY / (float)renderTarget.Height) * 0.5f; This is the code where I set the camera position and camera look ats // Position camera if (downwards) { float cameraHeight = bounds.Max.Y + 0.501f - (sliceHeight * i); Vector3 cameraPosition = new Vector3 ( boundsCentre.X, // possibly adjust by half a pixel? cameraHeight, boundsCentre.Z ); camera.Position = cameraPosition; camera.LookAt = new Vector3(cameraPosition.X, cameraHeight - 1.0f, cameraPosition.Z); } else { float cameraHeight = bounds.Max.Y - 0.501f - (sliceHeight * i); Vector3 cameraPosition = new Vector3 ( boundsCentre.X, cameraHeight, boundsCentre.Z ); camera.Position = cameraPosition; camera.LookAt = new Vector3(cameraPosition.X, cameraHeight + 1.0f, cameraPosition.Z); } Main Question Now you've seen all the problems and code you can guess it. My main question is. How do I align both camera's so that they each render exactly the same image (mirrored along the Y axis)? Figure 1 the original model rendered in blender

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• how to define a field of view for the entire map for shadow?

  - by Mehdi Bugnard

  I recently added "Shadow Mapping" in my XNA games to include shadows. I followed the nice and famous tutorial from "Riemers" : http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series3/Shadow_map.php . This code work nice and I can see my source of light and shadow. But the problem is that my light source does not match the field of view that I created. I want the light covers the entire map of my game. I don't know why , but the light only affect 2-3 cubes of my map. ScreenShot: (the emission of light illuminates only 2-3 blocks and not the full map) Here is my code i create the fieldOfView for LightviewProjection Matrix: Vector3 lightDir = new Vector3(10, 52, 10); lightPos = new Vector3(10, 52, 10); Matrix lightsView = Matrix.CreateLookAt(lightPos, new Vector3(105, 50, 105), new Vector3(0, 1, 0)); Matrix lightsProjection = Matrix.CreatePerspectiveFieldOfView(MathHelper.PiOver2, 1f, 20f, 1000f); lightsViewProjectionMatrix = lightsView * lightsProjection; As you can see , my nearPlane and FarPlane are set to 20f and 100f . So i don't know why the light stop after 2 cubes. it's should be bigger Here is set the value to my custom effect HLSL in the shader file /* SHADOW VALUE */ effectWorld.Parameters["LightDirection"].SetValue(lightDir); effectWorld.Parameters["xLightsWorldViewProjection"].SetValue(Matrix.Identity * .lightsViewProjectionMatrix); effectWorld.Parameters["xWorldViewProjection"].SetValue(Matrix.Identity * arcadia.camera.View * arcadia.camera.Projection); effectWorld.Parameters["xLightPower"].SetValue(1f); effectWorld.Parameters["xAmbient"].SetValue(0.3f); Here is my custom HLSL shader effect file "*.fx" // This sample uses a simple Lambert lighting model. float3 LightDirection = normalize(float3(-1, -1, -1)); float3 DiffuseLight = 1.25; float3 AmbientLight = 0.25; uniform const float3 DiffuseColor = 1; uniform const float Alpha = 1; uniform const float3 EmissiveColor = 0; uniform const float3 SpecularColor = 1; uniform const float SpecularPower = 16; uniform const float3 EyePosition; // FOG attribut uniform const float FogEnabled ; uniform const float FogStart ; uniform const float FogEnd ; uniform const float3 FogColor ; float3 cameraPos : CAMERAPOS; texture Texture; sampler Sampler = sampler_state { Texture = (Texture); magfilter = LINEAR; minfilter = LINEAR; mipfilter = LINEAR; AddressU = mirror; AddressV = mirror; }; texture xShadowMap; sampler ShadowMapSampler = sampler_state { Texture = <xShadowMap>; magfilter = LINEAR; minfilter = LINEAR; mipfilter = LINEAR; AddressU = clamp; AddressV = clamp; }; /* *************** */ /* SHADOW MAP CODE */ /* *************** */ struct SMapVertexToPixel { float4 Position : POSITION; float4 Position2D : TEXCOORD0; }; struct SMapPixelToFrame { float4 Color : COLOR0; }; struct SSceneVertexToPixel { float4 Position : POSITION; float4 Pos2DAsSeenByLight : TEXCOORD0; float2 TexCoords : TEXCOORD1; float3 Normal : TEXCOORD2; float4 Position3D : TEXCOORD3; }; struct SScenePixelToFrame { float4 Color : COLOR0; }; float DotProduct(float3 lightPos, float3 pos3D, float3 normal) { float3 lightDir = normalize(pos3D - lightPos); return dot(-lightDir, normal); } SSceneVertexToPixel ShadowedSceneVertexShader(float4 inPos : POSITION, float2 inTexCoords : TEXCOORD0, float3 inNormal : NORMAL) { SSceneVertexToPixel Output = (SSceneVertexToPixel)0; Output.Position = mul(inPos, xWorldViewProjection); Output.Pos2DAsSeenByLight = mul(inPos, xLightsWorldViewProjection); Output.Normal = normalize(mul(inNormal, (float3x3)World)); Output.Position3D = mul(inPos, World); Output.TexCoords = inTexCoords; return Output; } SScenePixelToFrame ShadowedScenePixelShader(SSceneVertexToPixel PSIn) { SScenePixelToFrame Output = (SScenePixelToFrame)0; float2 ProjectedTexCoords; ProjectedTexCoords[0] = PSIn.Pos2DAsSeenByLight.x / PSIn.Pos2DAsSeenByLight.w / 2.0f + 0.5f; ProjectedTexCoords[1] = -PSIn.Pos2DAsSeenByLight.y / PSIn.Pos2DAsSeenByLight.w / 2.0f + 0.5f; float diffuseLightingFactor = 0; if ((saturate(ProjectedTexCoords).x == ProjectedTexCoords.x) && (saturate(ProjectedTexCoords).y == ProjectedTexCoords.y)) { float depthStoredInShadowMap = tex2D(ShadowMapSampler, ProjectedTexCoords).r; float realDistance = PSIn.Pos2DAsSeenByLight.z / PSIn.Pos2DAsSeenByLight.w; if ((realDistance - 1.0f / 100.0f) <= depthStoredInShadowMap) { diffuseLightingFactor = DotProduct(xLightPos, PSIn.Position3D, PSIn.Normal); diffuseLightingFactor = saturate(diffuseLightingFactor); diffuseLightingFactor *= xLightPower; } } float4 baseColor = tex2D(Sampler, PSIn.TexCoords); Output.Color = baseColor*(diffuseLightingFactor + xAmbient); return Output; } SMapVertexToPixel ShadowMapVertexShader(float4 inPos : POSITION) { SMapVertexToPixel Output = (SMapVertexToPixel)0; Output.Position = mul(inPos, xLightsWorldViewProjection); Output.Position2D = Output.Position; return Output; } SMapPixelToFrame ShadowMapPixelShader(SMapVertexToPixel PSIn) { SMapPixelToFrame Output = (SMapPixelToFrame)0; Output.Color = PSIn.Position2D.z / PSIn.Position2D.w; return Output; } /* ******************* */ /* END SHADOW MAP CODE */ /* ******************* */ / For rendering without instancing. technique ShadowMap { pass Pass0 { VertexShader = compile vs_2_0 ShadowMapVertexShader(); PixelShader = compile ps_2_0 ShadowMapPixelShader(); } } technique ShadowedScene { /* pass Pass0 { VertexShader = compile vs_2_0 VSBasicTx(); PixelShader = compile ps_2_0 PSBasicTx(); } */ pass Pass1 { VertexShader = compile vs_2_0 ShadowedSceneVertexShader(); PixelShader = compile ps_2_0 ShadowedScenePixelShader(); } } technique SimpleFog { pass Pass0 { VertexShader = compile vs_2_0 VSBasicTx(); PixelShader = compile ps_2_0 PSBasicTx(); } } I edited my fx file , for show you only information and functions about the shadow ;-)

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• Tile map collision is not working properly

  - by Sigh-AniDe

  I am having problems setting collision between my sprite and the tiles. I have only done the code for colision for moving upwards but some places on the map it moves up and some places it doesn't. Here is what I have so far: Vector2 position; private static float scalingFactor = 32; static int tileWidth = 32; static int tileHeight = 32; int[ , ] map = { {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, {0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }, }; // This is in turtle.update if ( keyboardState.IsKeyDown( Keys.Up ) ) { if ( position.Y > screenHeight / 4 ) { //// current position of the turtle on the tiles int mapX = ( int )( position.X / scalingFactor ); int mapY = ( int )( position.Y / scalingFactor ) - 1; if ( isMovable( mapX , mapY , map ) ) { position.Y = position.Y - scalingFactor; } } else { MoveUp(); } } private void MoveUp() { motion.Y = -1; } public bool isMovable( int mapX , int mapY , int[ , ] map ) { if ( mapX < 0 || mapX > 19 || mapY < 0 || mapY > 20 ) { return false; } int tile = map[ mapX , mapY ]; if ( tile == 0 ) { return false; } return true; } protected override void Update( GameTime gameTime ) { turtle.Update( screenHeight , scalingFactor , map ); base.Update( gameTime ); }

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• Deserialize inherited classes into the same list in XNA

  - by M0rgenstern

  I am writing a Gui for a game (for what else ...). Therefor I wrote a class GuiElement which has some serializeable fields. From this class I deflect a Class "Button" which has one serializeable field more. Furthermore, I have a Class GuiWindow, which is as well deflected from "GuiElement". An Object of this Class has a Field "HandledElements" of the type "List". To know the layout of the Menues, I use XML-Files, which look like that (for example): <?xml version="1.0" encoding="utf-8" ?> <XnaContent xmlns:Generic="System.Collections.Generic"> <Asset Type="System.Collections.Generic.List[GUI.GuiWindow]"> <Item> <Position>0 0</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>true</IsActive> <Name>MainMenu</Name> <HandledElements> <Item> <Position>100 100</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>true</IsActive> <Name>Optionen</Name> <Caption>Optionen</Caption> </Item> </HandledElements> </Item> <Item> <Position>0 0</Position> <AlternativeImagePath></AlternativeImagePath> <IsActive>false</IsActive> <Name>Options</Name> <HandledElements> </HandledElements> </Item> </Asset> </XnaContent> As you can see, the first window has in its "HandledElements" List an Item with the Field . This is a field which only a Button has. The Problem is now: I can't deserialize this XML file, because GuiElement does not have this Field, it only has the few fields above. I thought it would know automatically which Class to use,but it doesn't. Do I really have to give my windows a list for each child class of GuiElement? Or can I do another workaround?

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• x axis detection issues platformer starter kit

  - by dbomb101

  I've come across a problem with the collision detection code in the platformer starter kit for xna.It will send up the impassible flag on the x axis despite being nowhere near a wall in either direction on the x axis, could someone could tell me why this happens ? Here is the collision method. /// <summary> /// Detects and resolves all collisions between the player and his neighboring /// tiles. When a collision is detected, the player is pushed away along one /// axis to prevent overlapping. There is some special logic for the Y axis to /// handle platforms which behave differently depending on direction of movement. /// </summary> private void HandleCollisions() { // Get the player's bounding rectangle and find neighboring tiles. Rectangle bounds = BoundingRectangle; int leftTile = (int)Math.Floor((float)bounds.Left / Tile.Width); int rightTile = (int)Math.Ceiling(((float)bounds.Right / Tile.Width)) - 1; int topTile = (int)Math.Floor((float)bounds.Top / Tile.Height); int bottomTile = (int)Math.Ceiling(((float)bounds.Bottom / Tile.Height)) - 1; // Reset flag to search for ground collision. isOnGround = false; // For each potentially colliding tile, for (int y = topTile; y <= bottomTile; ++y) { for (int x = leftTile; x <= rightTile; ++x) { // If this tile is collidable, TileCollision collision = Level.GetCollision(x, y); if (collision != TileCollision.Passable) { // Determine collision depth (with direction) and magnitude. Rectangle tileBounds = Level.GetBounds(x, y); Vector2 depth = RectangleExtensions.GetIntersectionDepth(bounds, tileBounds); if (depth != Vector2.Zero) { float absDepthX = Math.Abs(depth.X); float absDepthY = Math.Abs(depth.Y); // Resolve the collision along the shallow axis. if (absDepthY < absDepthX || collision == TileCollision.Platform) { // If we crossed the top of a tile, we are on the ground. if (previousBottom <= tileBounds.Top) isOnGround = true; // Ignore platforms, unless we are on the ground. if (collision == TileCollision.Impassable || IsOnGround) { // Resolve the collision along the Y axis. Position = new Vector2(Position.X, Position.Y + depth.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } //This is the section which deals with collision on the x-axis else if (collision == TileCollision.Impassable) // Ignore platforms. { // Resolve the collision along the X axis. Position = new Vector2(Position.X + depth.X, Position.Y); // Perform further collisions with the new bounds. bounds = BoundingRectangle; } } } } } // Save the new bounds bottom. previousBottom = bounds.Bottom; }

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• OpenGL Tessellation makes point

  - by urza57

  A little problem with my tessellation shader. I try to implement a simple tessellation shader but it only makes points. Here's my vertex shader : out vec4 ecPosition; out vec3 ecNormal; void main( void ) { vec4 position = gl_Vertex; gl_Position = gl_ModelViewProjectionMatrix * position; ecPosition = gl_ModelViewMatrix * position; ecNormal = normalize(gl_NormalMatrix * gl_Normal); } My tessellation control shader : layout(vertices = 3) out; out vec4 ecPosition3[]; in vec3 ecNormal[]; in vec4 ecPosition[]; out vec3 myNormal[]; void main() { gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position; myNormal[gl_InvocationID] = ecNormal[gl_InvocationID]; ecPosition3[gl_InvocationID] = ecPosition[gl_InvocationID]; gl_TessLevelOuter[0] = float(4.0); gl_TessLevelOuter[1] = float(4.0); gl_TessLevelOuter[2] = float(4.0); gl_TessLevelInner[0] = float(4.0); } And my Tessellation Evaluation shader: layout(triangles, equal_spacing, ccw) in; in vec3 myNormal[]; in vec4 ecPosition3[]; out vec3 ecNormal; out vec4 ecPosition; void main() { float u = gl_TessCoord.x; float v = gl_TessCoord.y; float w = gl_TessCoord.z; vec3 position = vec4(gl_in[0].gl_Position.xyz * u + gl_in[1].gl_Position.xyz * v + gl_in[2].gl_Position.xyz * w ); vec3 position2 = vec4(ecPosition3[0].xyz * u + ecPosition3[1].xyz * v + ecPosition3[2].xyz * w ); vec3 normal = myNormal[0] * u + myNormal[1] * v + myNormal[2] * w ); ecNormal = normal; gl_Position = vec4(position, 1.0); ecPosition = vec4(position2, 1.0); } Thank you !

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• Orthographic unit translation mismatch on grid (e.g. 64 pixels translates incorrectly)

  - by Justin Van Horne

  I am looking for some insight into a small problem with unit translations on a grid. Setup 512x448 window 64x64 grid gl_Position = projection * world * position; projection is defined by ortho(-w/2.0f, w/2.0f, -h/2.0f, h/2.0f); This is a textbook orthogonal projection function. world is defined by a fixed camera position at (0, 0) position is defined by the sprite's position. Problem In the screenshot below (1:1 scaling) the grid spacing is 64x64 and I am drawing the unit at (64, 64), however the unit draws roughly ~10px in the wrong position. I've tried uniform window dimensions to prevent any distortion on the pixel size, but now I am a bit lost in the proper way in providing a 1:1 pixel-to-world-unit projection. Anyhow, here are some quick images to aide in the problem. I decided to super-impose a bunch of the sprites at what the engine believes is 64x offsets. When this seemed off place, I went about and did the base case of 1 unit. Which seemed to line up as expected. The yellow shows a 1px difference in the movement. Vertices It would appear that the vertices going into the vertex shader are correct. For example, in reference to the first image the data looks like this in the VBO: x y x y ---------------------------- tl | 0.0 24.0 64.0 24.0 bl | 0.0 0.0 -> 64.0 0.0 tr | 16.0 0.0 80.0 0.0 br | 16.0 24.0 80.0 24.0 With that said, all I am left to believe is that I am munging up my actual projection. So, I am looking for any insight into maintaining the 1:1 pixel-to-world-unit projection.

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• Mandelbrot set not displaying properly

  - by brainydexter

  I am trying to render mandelbrot set using glsl. I'm not sure why its not rendering the correct shape. Does the mandelbrot calculation require values to be within a range for the (x,y) [ or (real, imag) ] ? Here is a screenshot: I render a quad as follows: float w2 = 6; float h2 = 5; glBegin(GL_QUADS); glVertex3f(-w2, h2, 0.0); glVertex3f(-w2, -h2, 0.0); glVertex3f(w2, -h2, 0.0); glVertex3f(w2, h2, 0.0); glEnd(); My vertex shader: varying vec3 Position; void main(void) { Position = gl_Vertex.xyz; gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; } My fragment shader (where all the meat is): uniform float MAXITERATIONS; varying vec3 Position; void main (void) { float zoom = 1.0; float centerX = 0.0; float centerY = 0.0; float real = Position.x * zoom + centerX; float imag = Position.y * zoom + centerY; float r2 = 0.0; float iter; for(iter = 0.0; iter < MAXITERATIONS && r2 < 4.0; ++iter) { float tempreal = real; real = (tempreal * tempreal) + (imag * imag); imag = 2.0 * real * imag; r2 = (real * real) + (imag * imag); } vec3 color; if(r2 < 4.0) color = vec3(1.0); else color = vec3( iter / MAXITERATIONS ); gl_FragColor = vec4(color, 1.0); }

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• Speed up lighting in deferred shading

  - by kochol

  I implemented a simple deferred shading renderer. I use 3 G-Buffer for storing position (R32F), normal (G16R16F) and albedo (ARGB8). I use sphere map algorithm to store normals in world space. Currently I use inverse of view * projection matrix to calculate the position of each pixel from stored depth value. First I want to avoid per pixel matrix multiplication for calculating the position. Is there another way to store and calculate position in G-Buffer without the need of matrix multiplication Store the normal in view space Every lighting in my engine is in world space and I want do the lighting in view space to speed up my lighting pass. I want an optimized lighting pass for my deferred engine.

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Android Swipe In Unity 3D World with AR

  - by Christian

  I am working on an AR application using Unity3D and the Vuforia SDK for Android. The way the application works is a when the designated image(a frame marker in our case) is recognized by the camera, a 3D island is rendered at that spot. Currently I am able to detect when/which objects are touched on the model by raycasting. I also am able to successfully detect a swipe using this code: if (Input.touchCount > 0) { Touch touch = Input.touches[0]; switch (touch.phase) { case TouchPhase.Began: couldBeSwipe = true; startPos = touch.position; startTime = Time.time; break; case TouchPhase.Moved: if (Mathf.Abs(touch.position.y - startPos.y) > comfortZoneY) { couldBeSwipe = false; } //track points here for raycast if it is swipe break; case TouchPhase.Stationary: couldBeSwipe = false; break; case TouchPhase.Ended: float swipeTime = Time.time - startTime; float swipeDist = (touch.position - startPos).magnitude; if (couldBeSwipe && (swipeTime < maxSwipeTime) && (swipeDist > minSwipeDist)) { // It's a swiiiiiiiiiiiipe! float swipeDirection = Mathf.Sign(touch.position.y - startPos.y); // Do something here in reaction to the swipe. swipeCounter.IncrementCounter(); } break; } touchInfo.SetTouchInfo (Time.time-startTime,(touch.position-startPos).magnitude,Mathf.Abs (touch.position.y-startPos.y)); } Thanks to andeeeee for the logic. But I want to have some interaction in the 3D world based on the swipe on the screen. I.E. If the user swipes over unoccluded enemies, they die. My first thought was to track all the points in the moved TouchPhase, and then if it is a swipe raycast into all those points and kill any enemy that is hit. Is there a better way to do this? What is the best approach? Thanks for the help!

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• Image 1 becomes image 2 with sliding effect from left to right?

  - by Paul

  I would like to show a second image appearing while a "door" is closing on my character. I've got my character in the middle of the screen and a door coming from the left. When the door passes my character, I would like to have this second image appearing little by little. So far, I've gotten by with fadingOut the character and then fadingIn my second image of the character at the same position when the door is completely closed, but I would like to have both of them at the same time. (the effect that image 1 becomes image 2 when the door is sliding from left to right). Would you know how to do this with Cocos2d? Here are the images : at first, the character is blue, and the door is coming from the left : Then, behind the black door, the character becomes red, but only behind this door, so it stays blue when the door is not on him, and will become completely red when the door passes the character : EDIT : with this code, the black door hides the red and blue rectangles : (And if i add each of my layers at a different depth, and only use GL_LESS, same thing) blue.position = ccp( size.width*0.5 , size.height/2 ); red.position = ccp( size.width*0.46 , size.height/2 ); black.position = ccp( size.width*0.1 , size.height/2 ); glEnable(GL_DEPTH_TEST); [batch addChild:red z:0]; [batch addChild:black z:2]; glDepthFunc(GL_GREATER); [batch addChild:blue z:1]; glDepthFunc(GL_LESS); id action1 = [CCMoveTo actionWithDuration:3 position:ccp(size.width,size.height/2)]; [black runAction: [CCSequence actions:action1, nil]];

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• XNA clip plane effect makes models black

  - by user1990950

  When using this effect file: float4x4 World; float4x4 View; float4x4 Projection; float4 ClipPlane0; void vs(inout float4 position : POSITION0, out float4 clipDistances : TEXCOORD0) { clipDistances.x = dot(position, ClipPlane0); clipDistances.y = 0; clipDistances.z = 0; clipDistances.w = 0; position = mul(mul(mul(position, World), View), Projection); } float4 ps(float4 clipDistances : TEXCOORD0) : COLOR0 { clip(clipDistances); return float4(0, 0, 0, 0); } technique { pass { VertexShader = compile vs_2_0 vs(); PixelShader = compile ps_2_0 ps(); } } all models using this are rendered black. Is it possible to render them correctly?

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• XNA shield effect with a Primative sphere problem

  - by Sparky41

  I'm having issue with a shield effect i'm trying to develop. I want to do a shield effect that surrounds part of a model like this: http://i.imgur.com/jPvrf.png I currently got this: http://i.imgur.com/Jdin7.png (The red likes are a simple texture a black background with a red cross in it, for testing purposes: http://i.imgur.com/ODtzk.png where the smaller cross in the middle shows the contact point) This sphere is drawn via a primitive (DrawIndexedPrimitives) This is how i calculate the pieces of the sphere using a class i've called Sphere (this class is based off the code here: http://xbox.create.msdn.com/en-US/education/catalog/sample/primitives_3d) public class Sphere { // During the process of constructing a primitive model, vertex // and index data is stored on the CPU in these managed lists. List vertices = new List(); List indices = new List(); // Once all the geometry has been specified, the InitializePrimitive // method copies the vertex and index data into these buffers, which // store it on the GPU ready for efficient rendering. VertexBuffer vertexBuffer; IndexBuffer indexBuffer; BasicEffect basicEffect; public Vector3 position = Vector3.Zero; public Matrix RotationMatrix = Matrix.Identity; public Texture2D texture; /// <summary> /// Constructs a new sphere primitive, /// with the specified size and tessellation level. /// </summary> public Sphere(float diameter, int tessellation, Texture2D text, float up, float down, float portstar, float frontback) { texture = text; if (tessellation < 3) throw new ArgumentOutOfRangeException("tessellation"); int verticalSegments = tessellation; int horizontalSegments = tessellation * 2; float radius = diameter / 2; // Start with a single vertex at the bottom of the sphere. AddVertex(Vector3.Down * ((radius / up) + 1), Vector3.Down, Vector2.Zero);//bottom position5 // Create rings of vertices at progressively higher latitudes. for (int i = 0; i < verticalSegments - 1; i++) { float latitude = ((i + 1) * MathHelper.Pi / verticalSegments) - MathHelper.PiOver2; float dy = (float)Math.Sin(latitude / up);//(up)5 float dxz = (float)Math.Cos(latitude); // Create a single ring of vertices at this latitude. for (int j = 0; j < horizontalSegments; j++) { float longitude = j * MathHelper.TwoPi / horizontalSegments; float dx = (float)(Math.Cos(longitude) * dxz) / portstar;//port and starboard (right)2 float dz = (float)(Math.Sin(longitude) * dxz) * frontback;//front and back1.4 Vector3 normal = new Vector3(dx, dy, dz); AddVertex(normal * radius, normal, new Vector2(j, i)); } } // Finish with a single vertex at the top of the sphere. AddVertex(Vector3.Up * ((radius / down) + 1), Vector3.Up, Vector2.One);//top position5 // Create a fan connecting the bottom vertex to the bottom latitude ring. for (int i = 0; i < horizontalSegments; i++) { AddIndex(0); AddIndex(1 + (i + 1) % horizontalSegments); AddIndex(1 + i); } // Fill the sphere body with triangles joining each pair of latitude rings. for (int i = 0; i < verticalSegments - 2; i++) { for (int j = 0; j < horizontalSegments; j++) { int nextI = i + 1; int nextJ = (j + 1) % horizontalSegments; AddIndex(1 + i * horizontalSegments + j); AddIndex(1 + i * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + j); AddIndex(1 + i * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + nextJ); AddIndex(1 + nextI * horizontalSegments + j); } } // Create a fan connecting the top vertex to the top latitude ring. for (int i = 0; i < horizontalSegments; i++) { AddIndex(CurrentVertex - 1); AddIndex(CurrentVertex - 2 - (i + 1) % horizontalSegments); AddIndex(CurrentVertex - 2 - i); } //InitializePrimitive(graphicsDevice); } /// <summary> /// Adds a new vertex to the primitive model. This should only be called /// during the initialization process, before InitializePrimitive. /// </summary> protected void AddVertex(Vector3 position, Vector3 normal, Vector2 texturecoordinate) { vertices.Add(new VertexPositionNormal(position, normal, texturecoordinate)); } /// <summary> /// Adds a new index to the primitive model. This should only be called /// during the initialization process, before InitializePrimitive. /// </summary> protected void AddIndex(int index) { if (index > ushort.MaxValue) throw new ArgumentOutOfRangeException("index"); indices.Add((ushort)index); } /// <summary> /// Queries the index of the current vertex. This starts at /// zero, and increments every time AddVertex is called. /// </summary> protected int CurrentVertex { get { return vertices.Count; } } public void InitializePrimitive(GraphicsDevice graphicsDevice) { // Create a vertex declaration, describing the format of our vertex data. // Create a vertex buffer, and copy our vertex data into it. vertexBuffer = new VertexBuffer(graphicsDevice, typeof(VertexPositionNormal), vertices.Count, BufferUsage.None); vertexBuffer.SetData(vertices.ToArray()); // Create an index buffer, and copy our index data into it. indexBuffer = new IndexBuffer(graphicsDevice, typeof(ushort), indices.Count, BufferUsage.None); indexBuffer.SetData(indices.ToArray()); // Create a BasicEffect, which will be used to render the primitive. basicEffect = new BasicEffect(graphicsDevice); //basicEffect.EnableDefaultLighting(); } /// <summary> /// Draws the primitive model, using the specified effect. Unlike the other /// Draw overload where you just specify the world/view/projection matrices /// and color, this method does not set any renderstates, so you must make /// sure all states are set to sensible values before you call it. /// </summary> public void Draw(Effect effect) { GraphicsDevice graphicsDevice = effect.GraphicsDevice; // Set our vertex declaration, vertex buffer, and index buffer. graphicsDevice.SetVertexBuffer(vertexBuffer); graphicsDevice.Indices = indexBuffer; graphicsDevice.BlendState = BlendState.Additive; foreach (EffectPass effectPass in effect.CurrentTechnique.Passes) { effectPass.Apply(); int primitiveCount = indices.Count / 3; graphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, vertices.Count, 0, primitiveCount); } graphicsDevice.BlendState = BlendState.Opaque; } /// <summary> /// Draws the primitive model, using a BasicEffect shader with default /// lighting. Unlike the other Draw overload where you specify a custom /// effect, this method sets important renderstates to sensible values /// for 3D model rendering, so you do not need to set these states before /// you call it. /// </summary> public void Draw(Camera camera, Color color) { // Set BasicEffect parameters. basicEffect.World = GetWorld(); basicEffect.View = camera.view; basicEffect.Projection = camera.projection; basicEffect.DiffuseColor = color.ToVector3(); basicEffect.TextureEnabled = true; basicEffect.Texture = texture; GraphicsDevice device = basicEffect.GraphicsDevice; device.DepthStencilState = DepthStencilState.Default; if (color.A < 255) { // Set renderstates for alpha blended rendering. device.BlendState = BlendState.AlphaBlend; } else { // Set renderstates for opaque rendering. device.BlendState = BlendState.Opaque; } // Draw the model, using BasicEffect. Draw(basicEffect); } public virtual Matrix GetWorld() { return /*world */ Matrix.CreateScale(1f) * RotationMatrix * Matrix.CreateTranslation(position); } } public struct VertexPositionNormal : IVertexType { public Vector3 Position; public Vector3 Normal; public Vector2 TextureCoordinate; /// <summary> /// Constructor. /// </summary> public VertexPositionNormal(Vector3 position, Vector3 normal, Vector2 textCoor) { Position = position; Normal = normal; TextureCoordinate = textCoor; } /// <summary> /// A VertexDeclaration object, which contains information about the vertex /// elements contained within this struct. /// </summary> public static readonly VertexDeclaration VertexDeclaration = new VertexDeclaration ( new VertexElement(0, VertexElementFormat.Vector3, VertexElementUsage.Position, 0), new VertexElement(12, VertexElementFormat.Vector3, VertexElementUsage.Normal, 0), new VertexElement(24, VertexElementFormat.Vector2, VertexElementUsage.TextureCoordinate, 0) ); VertexDeclaration IVertexType.VertexDeclaration { get { return VertexPositionNormal.VertexDeclaration; } } } A simple call to the class to initialise it. The Draw method is called in the master draw method in the Gamecomponent. My current thoughts on this are: The direction of the weapon hitting the ship is used to get the middle position for the texture Wrap a texture around the drawn sphere based on this point of contact Problem is i'm not sure how to do this. Can anyone help or if you have a better idea please tell me i'm open for opinion? :-) Thanks.

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• Camera movement and threshold not working

  - by irish guy mcconagheh

  I have a platformer that is in progress, part of this has a camera which I only want to move when the character moves out of a certain threshold, to try to accomplish this I have the following if statement: if(((Mathf.Abs(target.transform.position.x))-(Mathf.Abs(transform.position.x)))>thres){ x = moveTo(transform.position.x, target.position.x, trackSpeed); } in unity/c#. In pseudocode it means if((absolute value of player x) - (absolute value of camera x) is greater than the threshold){ move { however this does not seem to work correctly. it appears to work for the first couple of times the threshold is reached, however the distance between the camera and the player has to increase every time for the camera to move. I do not believe the movement of the camera is the problem, however the code for it is as follows: private float moveTo(float n, float target, float accel) { if (n == target) { return n; } else { float dir = Mathf.Sign(target - n); n += accel * Time.deltaTime * dir; return (dir == Mathf.Sign(target-n))? n: target; } } }

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• Data Transformation Pipeline

  - by davenewza

  I have create some kind of data pipeline to transform coordinate data into more useful information. Here is the shell of pipeline: public class PositionPipeline { protected List<IPipelineComponent> components; public PositionPipeline() { components = new List<IPipelineComponent>(); } public PositionPipelineEntity Process(Position position) { foreach (var component in components) { position = component.Execute(position); } return position; } public PositionPipeline RegisterComponent(IPipelineComponent component) { components.Add(component); return this; } } Every IPipelineComponent accepts and returns the same type - a PositionPipelineEntity. Code: public interface IPipelineComponent { PositionPipelineEntity Execute(PositionPipelineEntity position); } The PositionPipelineEntity needs to have many properties, many which are unused in certain components and required in others. Some properties will also have become redundant at the end of the pipeline. For example, these components could be executed: TransformCoordinatesComponent: Parse the raw coordinate data into a Coordinate type. DetermineCountryComponent: Determine and stores country code. DetermineOnRoadComponent: Determine and store whether coordinate is on a road. Code: pipeline .RegisterComponent(new TransformCoordinatesComponent()) .RegisterComponent(new DetermineCountryComponent()) .RegisterComponent(new DetermineOnRoadComponent()); pipeline.Process(positionPipelineEntity); The PositionPipelineEntity type: public class PositionPipelineEntity { // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLatitude { get; set; } // Only relevant to the TransformCoordinatesComponent public decimal RawCoordinateLongitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLatitude { get; set; } // Required by all components after TransformCoordinatesComponent public Coordinate CoordinateLongitude { get; set; } // Set in DetermineCountryComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public string CountryCode { get; set; } // Set in DetermineOnRoadComponent, not required anywhere. // Requires CoordinateLatitude and CoordinateLongitude (TransformCoordinatesComponent) public bool OnRoad { get; set; } } Problems: I'm very concerned about the dependency that a component has on properties. The way to solve this would be to create specific types for each component. The problem then is that I cannot chain them together like this. The other problem is the order of components in the pipeline matters. There is some dependency. The current structure does not provide any static or runtime checking for such a thing. Any feedback would be appreciated.

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• Help understand GLSL directional light on iOS (left handed coord system)

  - by Robse

  I now have changed from GLKBaseEffect to a own shader implementation. I have a shader management, which compiles and applies a shader to the right time and does some shader setup like lights. Please have a look at my vertex shader code. Now, light direction should be provided in eye space, but I think there is something I don't get right. After I setup my view with camera I save a lightMatrix to transform the light from global space to eye space. My modelview and projection setup: - (void)setupViewWithWidth:(int)width height:(int)height camera:(N3DCamera *)aCamera { aCamera.aspect = (float)width / (float)height; float aspect = aCamera.aspect; float far = aCamera.far; float near = aCamera.near; float vFOV = aCamera.fieldOfView; float top = near * tanf(M_PI * vFOV / 360.0f); float bottom = -top; float right = aspect * top; float left = -right; // projection GLKMatrixStackLoadMatrix4(projectionStack, GLKMatrix4MakeFrustum(left, right, bottom, top, near, far)); // identity modelview GLKMatrixStackLoadMatrix4(modelviewStack, GLKMatrix4Identity); // switch to left handed coord system (forward = z+) GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeScale(1, 1, -1)); // transform camera GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeWithMatrix3(GLKMatrix3Transpose(aCamera.orientation))); GLKMatrixStackTranslate(modelviewStack, -aCamera.position.x, -aCamera.position.y, -aCamera.position.z); } - (GLKMatrix4)modelviewMatrix { return GLKMatrixStackGetMatrix4(modelviewStack); } - (GLKMatrix4)projectionMatrix { return GLKMatrixStackGetMatrix4(projectionStack); } - (GLKMatrix4)modelviewProjectionMatrix { return GLKMatrix4Multiply([self projectionMatrix], [self modelviewMatrix]); } - (GLKMatrix3)normalMatrix { return GLKMatrix3InvertAndTranspose(GLKMatrix4GetMatrix3([self modelviewProjectionMatrix]), NULL); } After that, I save the lightMatrix like this: [self.renderer setupViewWithWidth:view.drawableWidth height:view.drawableHeight camera:self.camera]; self.lightMatrix = [self.renderer modelviewProjectionMatrix]; And just before I render a 3d entity of the scene graph, I setup the light config for its shader with the lightMatrix like this: - (N3DLight)transformedLight:(N3DLight)light transformation:(GLKMatrix4)matrix { N3DLight transformedLight = N3DLightMakeDisabled(); if (N3DLightIsDirectional(light)) { GLKVector3 direction = GLKVector3MakeWithArray(GLKMatrix4MultiplyVector4(matrix, light.position).v); direction = GLKVector3Negate(direction); // HACK -> TODO: get lightMatrix right! transformedLight = N3DLightMakeDirectional(direction, light.diffuse, light.specular); } else { ... } return transformedLight; } You see the line, where I negate the direction!? I can't explain why I need to do that, but if I do, the lights are correct as far as I can tell. Please help me, to get rid of the hack. I'am scared that this has something to do, with my switch to left handed coord system. My vertex shader looks like this: attribute highp vec4 inPosition; attribute lowp vec4 inNormal; ... uniform highp mat4 MVP; uniform highp mat4 MV; uniform lowp mat3 N; uniform lowp vec4 constantColor; uniform lowp vec4 ambient; uniform lowp vec4 light0Position; uniform lowp vec4 light0Diffuse; uniform lowp vec4 light0Specular; varying lowp vec4 vColor; varying lowp vec3 vTexCoord0; vec4 calcDirectional(vec3 dir, vec4 diffuse, vec4 specular, vec3 normal) { float NdotL = max(dot(normal, dir), 0.0); return NdotL * diffuse; } ... vec4 calcLight(vec4 pos, vec4 diffuse, vec4 specular, vec3 normal) { if (pos.w == 0.0) { // Directional Light return calcDirectional(normalize(pos.xyz), diffuse, specular, normal); } else { ... } } void main(void) { // position highp vec4 position = MVP * inPosition; gl_Position = position; // normal lowp vec3 normal = inNormal.xyz / inNormal.w; normal = N * normal; normal = normalize(normal); // colors vColor = constantColor * ambient; // add lights vColor += calcLight(light0Position, light0Diffuse, light0Specular, normal); ... }

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• Jittery Movement, Uncontrollably Rotating + Front of Sprite?

  - by Vipar

  So I've been looking around to try and figure out how I make my sprite face my mouse. So far the sprite moves to where my mouse is by some vector math. Now I'd like it to rotate and face the mouse as it moves. From what I've found this calculation seems to be what keeps reappearing: Sprite Rotation = Atan2(Direction Vectors Y Position, Direction Vectors X Position) I express it like so: sp.Rotation = (float)Math.Atan2(directionV.Y, directionV.X); If I just go with the above, the sprite seems to jitter left and right ever so slightly but never rotate out of that position. Seeing as Atan2 returns the rotation in radians I found another piece of calculation to add to the above which turns it into degrees: sp.Rotation = (float)Math.Atan2(directionV.Y, directionV.X) * 180 / PI; Now the sprite rotates. Problem is that it spins uncontrollably the closer it comes to the mouse. One of the problems with the above calculation is that it assumes that +y goes up rather than down on the screen. As I recorded in these two videos, the first part is the slightly jittery movement (A lot more visible when not recording) and then with the added rotation: Jittery Movement So my questions are: How do I fix that weird Jittery movement when the sprite stands still? Some have suggested to make some kind of "snap" where I set the position of the sprite directly to the mouse position when it's really close. But no matter what I do the snapping is noticeable. How do I make the sprite stop spinning uncontrollably? Is it possible to simply define the front of the sprite and use that to make it "face" the right way?

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• Design pattern for an automated mechanical test bench

  - by JJS

  Background I have a test fixture with a number of communication/data acquisition devices on it that is used as an end of line test for a product. Because of all the various sensors used in the bench and the need to run the test procedure in near real-time, I'm having a hard time structuring the program to be more friendly to modify later on. For example, a National Instruments USB data acquisition device is used to control an analog output (load) and monitor an analog input (current), a digital scale with a serial data interface measures position, an air pressure gauge with a different serial data interface, and the product is interfaced through a proprietary DLL that handles its own serial communication. The hard part The "real-time" aspect of the program is my biggest tripping point. For example, I need to time how long the product needs to go from position 0 to position 10,000 to the tenth of a second. While it's traveling, I need to ramp up an output of the NI DAQ when it reaches position 6,000 and ramp it down when it reaches position 8,000. This sort of control looks easy from browsing NI's LabVIEW docs but I'm stuck with C# for now. All external communication is done by polling which makes for lots of annoying loops. I've slapped together a loose Producer Consumer model where the Producer thread loops through reading the sensors and sets the outputs. The Consumer thread executes functions containing timed loops that poll the Producer for current data and execute movement commands as required. The UI thread polls both threads for updating some gauges indicating current test progress. Unsure where to start Is there a more appropriate pattern for this type of application? Are there any good resources for writing control loops in software (non-LabVIEW) that interface with external sensors and whatnot?

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• Interpolation between two 3D points?

  - by meds

  I'm working with some splines which define a path a character follows (you can see a gameplay video here to get a better understanding of what's going on: http://www.youtube.com/watch?v=BndobjOiZ6g). Basically the characters 'forward' look direction is set to the 'forward' direction of the spline and when players tilt their phone left and right the character is strafed along its 'right' coordinate. The issue with this is (rather obviously) in performance, interpolating over a spline to find the nearest position and tangent relative to the player is an incredibly costly operation. To get by this I cache a finite number of positions in what I call 'SplineDetails', the class is as follows: public class SplineDetails { public SplineDetails() { Forward = Vector3.forward; Position = Vector3.one * float.MaxValue; Alpha = -1; } public float Alpha; // [0,1] measured along length of spline where 0 is the initial point and 1 is the end point of the spline public Vector3 Position; // the point of the spline at this alpha public Vector3 Forward; // the forward tangent of the spline at this alpha } I populate this with say 30 coordinates and I can give a rough estimate of a coordinate and 'forward' based on a position past in. It's not as accurate but it's much faster. But now I'd like to make the system work better by estimating positions and 'forward' directions by interpolating between two of the cached points though I'm stuck trying to figure out some logic. My first problem is, how can I determine between which two points the object is? Given each point can be placed at different intervals along the spline it could mean that two points in front or behind the object can be closer to the object. The other problem is to figure out the proportion between the two paths it's between, i.e. if there is a point a at coordinate (0,0,0) and point b at coordinate (1,0,0) if the object is at position (0.5,0,0) then the result it should give is '0.5' (as it is equal distance away from point a and point b). That's a simple example, but what if the object is at coordinate (0.5,3,0) for example?

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• Disappearring instances of VertexPositionColor using MonoGame

  - by Rosko

  I am a complete beginner in graphics developing with XNA/Monogame. Started my own project using Monogame 3.0 for WinRT. I have this unexplainable issue that some of the vertices disappear while doing some updates on them. Basically, it is a game with balls who collide with the walls and with each other and in certain conditions they explode. When they explode they disappear. Here is a video demonstrating the issue. I used wireframes so that it is easier to see how vertices are missing. The perfect exploding balls are the ones which are result by user input with mouse clicking. Thanks for the help. The situations is: I draw user primitives with triangle strips using like this graphicsDevice.DrawUserPrimitives<VertexPositionColor>(PrimitiveType.TriangleStrip, circleVertices, 0, primitiveCount); All of the primitives are in the z-plane (z = 0), I thought that it is the culling in action. I tried setting the culling mode to none but it did not help. Here is the code responsible for the explosion private void Explode(GameTime gameTime, ref List<Circle> circles) { if (this.isExploding) { for (int i = 0; i < this.circleVertices.Length; i++) { if (this.circleVertices[i] != this.circleCenter) { if (Vector3.Distance(this.circleVertices[i].Position, this.circleCenter.Position) < this.explosionRadius * precisionCoefficient) { var explosionVector = this.circleVertices[i].Position - this.circleCenter.Position; explosionVector.Normalize(); explosionVector *= explosionSpeed; circleVertices[i].Position += explosionVector * (float)gameTime.ElapsedGameTime.TotalSeconds; } else { circles.Remove(this); } } } } } I'd be really greatful if anyone has suggestions about how to fix this issue.

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• How to get a point to the left/right of a vector

  - by MulletDevil

  I have a position vector of a point in space and a quaternion for it's rotation. What i'm trying to calculate is a point too the left and a point to the right. I have the position and rotation(quaternion) of the red dot. What I want is to get the position of the green dots. I have a float value for the distance I want these points to be. With only the position and rotation is it possible to get a unit direction vector pointing left/right which I can multiply by my float value? Edit: I also know the original direction vector.

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• Multithreading 2D gravity calculations

  - by Postman

  I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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• Moving 2d camera in the y direction

  - by Alex

  I'm developing a simple game for the iphone and am struggling to work out the best way for the camera to follow the main character. The following picture hightlights the three main components: There are 3 components to this: Circle - the main character Green line - terrain Black background The terrain is simply made from an array of points (approx 20 points per screen width). The terrain is moved in the x direction relative to the black background in order to keep the circle in its position shown. The distance to move the terrain is simply: movex = circle.position.x - terrain.position.x with a constant to fix the circle at some distance from the left of the screen. I am struggling to determine the best way to position the terrain in the y plane keep the focus in the character. I want to move the terrain in the y direction smoothly and not fix it to the position of the circle, so the circle can move in the y plane. If I take the same approach as the x positioning, the character is fixed at a point on the screen and the terrain moves. I could sample some terrain points either side of the character and produce an average, but in my implementation this was not smooth. I thought another approach might be to create a camera 'line' that is a smooth version of the terrain line and make the camerea follow this, but I'm not sure if this is the optimum solution. Any advice is much appreciated!

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