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  • Multiplication for MVP matrices: Any benefits to doing so within the vertex shader?

    - by Nick Wiggill
    I'd like to understand under what circumstances (if any) it is worth doing MVP matrix multiplication inside a vertex shader. The vertex shader is run once per vertex, and a single mesh typically contains many vertices. All MVP inputs remain the same for each vertex in the vertex batch relating to a given draw call (model). Surely then, you're always better off keeping the multiplications in the client code, such that you pass in the whole MVP precalculated as a uniform? (avoiding redundant ops between individual vertices)

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  • My vertex shader doesn't affect texture coords or diffuse info but works for position

    - by tina nyaa
    I am new to 3D and DirectX - in the past I have only used abstractions for 2D drawing. Over the past month I've been studying really hard and I'm trying to modify and adapt some of the shaders as part of my personal 'study project'. Below I have a shader, modified from one of the Microsoft samples. I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? // // Skinned Mesh Effect file // Copyright (c) 2000-2002 Microsoft Corporation. All rights reserved. // float4 lhtDir = {0.0f, 0.0f, -1.0f, 1.0f}; //light Direction float4 lightDiffuse = {0.6f, 0.6f, 0.6f, 1.0f}; // Light Diffuse float4 MaterialAmbient : MATERIALAMBIENT = {0.1f, 0.1f, 0.1f, 1.0f}; float4 MaterialDiffuse : MATERIALDIFFUSE = {0.8f, 0.8f, 0.8f, 1.0f}; // Matrix Pallette static const int MAX_MATRICES = 100; float4x3 mWorldMatrixArray[MAX_MATRICES] : WORLDMATRIXARRAY; float4x4 mViewProj : VIEWPROJECTION; /////////////////////////////////////////////////////// struct VS_INPUT { float4 Pos : POSITION; float4 BlendWeights : BLENDWEIGHT; float4 BlendIndices : BLENDINDICES; float3 Normal : NORMAL; float3 Tex0 : TEXCOORD0; }; struct VS_OUTPUT { float4 Pos : POSITION; float4 Diffuse : COLOR; float2 Tex0 : TEXCOORD0; }; float3 Diffuse(float3 Normal) { float CosTheta; // N.L Clamped CosTheta = max(0.0f, dot(Normal, lhtDir.xyz)); // propogate scalar result to vector return (CosTheta); } VS_OUTPUT VShade(VS_INPUT i, uniform int NumBones) { VS_OUTPUT o; float3 Pos = 0.0f; float3 Normal = 0.0f; float LastWeight = 0.0f; // Compensate for lack of UBYTE4 on Geforce3 int4 IndexVector = D3DCOLORtoUBYTE4(i.BlendIndices); // cast the vectors to arrays for use in the for loop below float BlendWeightsArray[4] = (float[4])i.BlendWeights; int IndexArray[4] = (int[4])IndexVector; // calculate the pos/normal using the "normal" weights // and accumulate the weights to calculate the last weight for (int iBone = 0; iBone < NumBones-1; iBone++) { LastWeight = LastWeight + BlendWeightsArray[iBone]; Pos += mul(i.Pos, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; Normal += mul(i.Normal, mWorldMatrixArray[IndexArray[iBone]]) * BlendWeightsArray[iBone]; } LastWeight = 1.0f - LastWeight; // Now that we have the calculated weight, add in the final influence Pos += (mul(i.Pos, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); Normal += (mul(i.Normal, mWorldMatrixArray[IndexArray[NumBones-1]]) * LastWeight); // transform position from world space into view and then projection space //o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Pos = mul(float4(Pos.xyz, 1.0f), mViewProj); o.Diffuse.x = 0.0f; o.Diffuse.y = 0.0f; o.Diffuse.z = 0.0f; o.Diffuse.w = 0.0f; o.Tex0 = float2(0,0); return o; } technique t0 { pass p0 { VertexShader = compile vs_3_0 VShade(4); } } I am currently using the SlimDX .NET wrapper around DirectX, but the API is extremely similar: public void Draw() { var device = vertexBuffer.Device; device.Clear(ClearFlags.Target | ClearFlags.ZBuffer, Color.White, 1.0f, 0); device.SetRenderState(RenderState.Lighting, true); device.SetRenderState(RenderState.DitherEnable, true); device.SetRenderState(RenderState.ZEnable, true); device.SetRenderState(RenderState.CullMode, Cull.Counterclockwise); device.SetRenderState(RenderState.NormalizeNormals, true); device.SetSamplerState(0, SamplerState.MagFilter, TextureFilter.Anisotropic); device.SetSamplerState(0, SamplerState.MinFilter, TextureFilter.Anisotropic); device.SetTransform(TransformState.World, Matrix.Identity * Matrix.Translation(0, -50, 0)); device.SetTransform(TransformState.View, Matrix.LookAtLH(new Vector3(-200, 0, 0), Vector3.Zero, Vector3.UnitY)); device.SetTransform(TransformState.Projection, Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); var material = new Material(); material.Ambient = material.Diffuse = material.Emissive = material.Specular = new Color4(Color.White); material.Power = 1f; device.SetStreamSource(0, vertexBuffer, 0, vertexSize); device.VertexDeclaration = vertexDeclaration; device.Indices = indexBuffer; device.Material = material; device.SetTexture(0, texture); var param = effect.GetParameter(null, "mWorldMatrixArray"); var boneWorldTransforms = bones.OrderedBones.OrderBy(x => x.Id).Select(x => x.CombinedTransformation).ToArray(); effect.SetValue(param, boneWorldTransforms); effect.SetValue(effect.GetParameter(null, "mViewProj"), Matrix.Identity);// Matrix.PerspectiveFovLH((float)Math.PI / 4, (float)device.Viewport.Width / device.Viewport.Height, 10, 10000000)); effect.SetValue(effect.GetParameter(null, "MaterialDiffuse"), material.Diffuse); effect.SetValue(effect.GetParameter(null, "MaterialAmbient"), material.Ambient); effect.Technique = effect.GetTechnique(0); var passes = effect.Begin(FX.DoNotSaveState); for (var i = 0; i < passes; i++) { effect.BeginPass(i); device.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, skin.Vertices.Length, 0, skin.Indicies.Length / 3); effect.EndPass(); } effect.End(); } Again, I set diffuse and tex0 vertex shader outputs to zero, but my model still shows the full texture and lighting as if I hadn't changed the values from the vertex buffer. Changing the position of the model works, but nothing else. Why is this? Also, whatever I set in the bone transformation matrices doesn't seem to have an effect on my model. If I set every bone transformation to a zero matrix, the model still shows up as if nothing had happened, but changing the Pos field in shader output makes the model disappear. I don't understand why I'm getting this kind of behaviour. Thank you!

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  • Why does OpenGL's glDrawArrays() fail with GL_INVALID_OPERATION under Core Profile 3.2, but not 3.3 or 4.2?

    - by metaleap
    I have OpenGL rendering code calling glDrawArrays that works flawlessly when the OpenGL context is (automatically / implicitly obtained) 4.2 but fails consistently (GL_INVALID_OPERATION) with an explicitly requested OpenGL core context 3.2. (Shaders are always set to #version 150 in both cases but that's beside the point here I suspect.) According to specs, there are only two instances when glDrawArrays() fails with GL_INVALID_OPERATION: "if a non-zero buffer object name is bound to an enabled array and the buffer object's data store is currently mapped" -- I'm not doing any buffer mapping at this point "if a geometry shader is active and mode? is incompatible with [...]" -- nope, no geometry shaders as of now. Furthermore: I have verified & double-checked that it's only the glDrawArrays() calls failing. Also double-checked that all arguments passed to glDrawArrays() are identical under both GL versions, buffer bindings too. This happens across 3 different nvidia GPUs and 2 different OSes (Win7 and OSX, both 64-bit -- of course, in OSX we have only the 3.2 context, no 4.2 anyway). It does not happen with an integrated "Intel HD" GPU but for that one, I only get an automatic implicit 3.3 context (trying to explicitly force a 3.2 core profile with this GPU via GLFW here fails the window creation but that's an entirely different issue...) For what it's worth, here's the relevant routine excerpted from the render loop, in Golang: func (me *TMesh) render () { curMesh = me curTechnique.OnRenderMesh() gl.BindBuffer(gl.ARRAY_BUFFER, me.glVertBuf) if me.glElemBuf > 0 { gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, me.glElemBuf) gl.VertexAttribPointer(curProg.AttrLocs["aPos"], 3, gl.FLOAT, gl.FALSE, 0, gl.Pointer(nil)) gl.DrawElements(me.glMode, me.glNumIndices, gl.UNSIGNED_INT, gl.Pointer(nil)) gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, 0) } else { gl.VertexAttribPointer(curProg.AttrLocs["aPos"], 3, gl.FLOAT, gl.FALSE, 0, gl.Pointer(nil)) /* BOOM! */ gl.DrawArrays(me.glMode, 0, me.glNumVerts) } gl.BindBuffer(gl.ARRAY_BUFFER, 0) } So of course this is part of a bigger render-loop, though the whole "*TMesh" construction for now is just two instances, one a simple cube and the other a simple pyramid. What matters is that the entire drawing loop works flawlessly with no errors reported when GL is queried for errors under both 3.3 and 4.2, yet on 3 nvidia GPUs with an explicit 3.2 core profile fails with an error code that according to spec is only invoked in two specific situations, none of which as far as I can tell apply here. What could be wrong here? Have you ever run into this? Any ideas what I have been missing?

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  • Ambient occlusion shader just shows models as all white

    - by dvds414
    Okay so I have this shader for ambient occlusion. It loads to world correctly, but it just shows all the models as being white. I do not know why. I am just running the shader while the model is rendering, is that correct? or do I need to make a render target or something? If so then how? I'm using C++. Here is my shader: float sampleRadius; float distanceScale; float4x4 xProjection; float4x4 xView; float4x4 xWorld; float3 cornerFustrum; struct VS_OUTPUT { float4 pos : POSITION; float2 TexCoord : TEXCOORD0; float3 viewDirection : TEXCOORD1; }; VS_OUTPUT VertexShaderFunction( float4 Position : POSITION, float2 TexCoord : TEXCOORD0) { VS_OUTPUT Out = (VS_OUTPUT)0; float4 WorldPosition = mul(Position, xWorld); float4 ViewPosition = mul(WorldPosition, xView); Out.pos = mul(ViewPosition, xProjection); Position.xy = sign(Position.xy); Out.TexCoord = (float2(Position.x, -Position.y) + float2( 1.0f, 1.0f ) ) * 0.5f; float3 corner = float3(-cornerFustrum.x * Position.x, cornerFustrum.y * Position.y, cornerFustrum.z); Out.viewDirection = corner; return Out; } texture depthTexture; texture randomTexture; sampler2D depthSampler = sampler_state { Texture = <depthTexture>; ADDRESSU = CLAMP; ADDRESSV = CLAMP; MAGFILTER = LINEAR; MINFILTER = LINEAR; }; sampler2D RandNormal = sampler_state { Texture = <randomTexture>; ADDRESSU = WRAP; ADDRESSV = WRAP; MAGFILTER = LINEAR; MINFILTER = LINEAR; }; float4 PixelShaderFunction(VS_OUTPUT IN) : COLOR0 { float4 samples[16] = { float4(0.355512, -0.709318, -0.102371, 0.0 ), float4(0.534186, 0.71511, -0.115167, 0.0 ), float4(-0.87866, 0.157139, -0.115167, 0.0 ), float4(0.140679, -0.475516, -0.0639818, 0.0 ), float4(-0.0796121, 0.158842, -0.677075, 0.0 ), float4(-0.0759516, -0.101676, -0.483625, 0.0 ), float4(0.12493, -0.0223423, -0.483625, 0.0 ), float4(-0.0720074, 0.243395, -0.967251, 0.0 ), float4(-0.207641, 0.414286, 0.187755, 0.0 ), float4(-0.277332, -0.371262, 0.187755, 0.0 ), float4(0.63864, -0.114214, 0.262857, 0.0 ), float4(-0.184051, 0.622119, 0.262857, 0.0 ), float4(0.110007, -0.219486, 0.435574, 0.0 ), float4(0.235085, 0.314707, 0.696918, 0.0 ), float4(-0.290012, 0.0518654, 0.522688, 0.0 ), float4(0.0975089, -0.329594, 0.609803, 0.0 ) }; IN.TexCoord.x += 1.0/1600.0; IN.TexCoord.y += 1.0/1200.0; normalize (IN.viewDirection); float depth = tex2D(depthSampler, IN.TexCoord).a; float3 se = depth * IN.viewDirection; float3 randNormal = tex2D( RandNormal, IN.TexCoord * 200.0 ).rgb; float3 normal = tex2D(depthSampler, IN.TexCoord).rgb; float finalColor = 0.0f; for (int i = 0; i < 16; i++) { float3 ray = reflect(samples[i].xyz,randNormal) * sampleRadius; //if (dot(ray, normal) < 0) // ray += normal * sampleRadius; float4 sample = float4(se + ray, 1.0f); float4 ss = mul(sample, xProjection); float2 sampleTexCoord = 0.5f * ss.xy/ss.w + float2(0.5f, 0.5f); sampleTexCoord.x += 1.0/1600.0; sampleTexCoord.y += 1.0/1200.0; float sampleDepth = tex2D(depthSampler, sampleTexCoord).a; if (sampleDepth == 1.0) { finalColor ++; } else { float occlusion = distanceScale* max(sampleDepth - depth, 0.0f); finalColor += 1.0f / (1.0f + occlusion * occlusion * 0.1); } } return float4(finalColor/16, finalColor/16, finalColor/16, 1.0f); } technique SSAO { pass P0 { VertexShader = compile vs_3_0 VertexShaderFunction(); PixelShader = compile ps_3_0 PixelShaderFunction(); } }

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  • glsl shader to allow color change of skydome ogre3d

    - by Tim
    I'm still very new to all this but learning a lot. I'm putting together an application using Ogre3d as the rendering engine. So far I've got it running, with a simple scene, a day/night cycle system which is working okay. I'm now moving on to looking at changing the color of the skydome material based on the time of day. What I've done so far is to create a struct to hold the ColourValues for the different aspects of the scene. struct todColors { Ogre::ColourValue sky; Ogre::ColourValue ambient; Ogre::ColourValue sun; }; I created an array to store all the colours todColors sceneColours [4]; I populated the array with the colours I want to use for the various times of the day. For instance DayTime (when the sun is high in the sky) sceneColours[2].sky = Ogre::ColourValue(135/255, 206/255, 235/255, 255); sceneColours[2].ambient = Ogre::ColourValue(135/255, 206/255, 235/255, 255); sceneColours[2].sun = Ogre::ColourValue(135/255, 206/255, 235/255, 255); I've got code to work out the time of the day using a float currentHours to store the current hour of the day 10.5 = 10:30 am. This updates constantly and updates the sun as required. I am then calculating the appropriate colours for the time of day when relevant using else if( currentHour >= 4 && currentHour < 7) { // Lerp from night to morning Ogre::ColourValue lerp = Ogre::Math::lerp<Ogre::ColourValue, float>(sceneColours[GT_TOD_NIGHT].sky , sceneColours[GT_TOD_MORNING].sky, (currentHour - 4) / (7 - 4)); } My original attempt to get this to work was to dynamically generate a material with the new colour and apply that material to the skydome. This, as you can probably guess... didn't go well. I know it's possible to use shaders where you can pass information such as colour to the shader from the code but I am unsure if there is an existing simple shader to change a colour like this or if I need to create one. What is involved in creating a shader and material definition that would allow me to change the colour of a material without the overheads of dynamically generating materials all the time? EDIT : I've created a glsl vertex and fragment shaders as follows. Vertex uniform vec4 newColor; void main() { gl_FrontColor = newColor; gl_Position = ftransform(); } Fragment void main() { gl_FragColor = gl_Color; } I can pass a colour to it using ShaderDesigner and it seems to work. I now need to investigate how to use it within Ogre as a material. EDIT : I created a material file like this : vertex_program colour_vs_test glsl { source test.vert default_params { param_named newColor float4 0.0 0.0 0.0 1 } } fragment_program colour_fs_glsl glsl { source test.frag } material Test/SkyColor { technique { pass { lighting off fragment_program_ref colour_fs_glsl { } vertex_program_ref colour_vs_test { } } } } In the code I have tried : Ogre::MaterialPtr material = Ogre::MaterialManager::getSingleton().getByName("Test/SkyColor"); Ogre::GpuProgramParametersSharedPtr params = material->getTechnique(0)->getPass(0)->getVertexProgramParameters(); params->setNamedConstant("newcolor", Ogre::Vector4(0.7, 0.5, 0.3, 1)); I've set that as the Skydome material which seems to work initially. I am doing the same with the code that is attempting to lerp between colours, but when I include it there, it all goes black. Seems like there is now a problem with my colour lerping.

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  • HLSL Shader not working right?

    - by dvds414
    Okay so I have this shader for ambient occlusion. It loads to world correctly, but it just shows all the models as being white. I do not know why. I am just running the shader while the model is rendering, is that correct? or do I need to make a render target or something? if so then how? I'm using C++. Here is my shader. float sampleRadius; float distanceScale; float4x4 xProjection; float4x4 xView; float4x4 xWorld; float3 cornerFustrum; struct VS_OUTPUT { float4 pos : POSITION; float2 TexCoord : TEXCOORD0; float3 viewDirection : TEXCOORD1; }; VS_OUTPUT VertexShaderFunction( float4 Position : POSITION, float2 TexCoord : TEXCOORD0) { VS_OUTPUT Out = (VS_OUTPUT)0; float4 WorldPosition = mul(Position, xWorld); float4 ViewPosition = mul(WorldPosition, xView); Out.pos = mul(ViewPosition, xProjection); Position.xy = sign(Position.xy); Out.TexCoord = (float2(Position.x, -Position.y) + float2( 1.0f, 1.0f ) ) * 0.5f; float3 corner = float3(-cornerFustrum.x * Position.x, cornerFustrum.y * Position.y, cornerFustrum.z); Out.viewDirection = corner; return Out; } texture depthTexture; texture randomTexture; sampler2D depthSampler = sampler_state { Texture = <depthTexture>; ADDRESSU = CLAMP; ADDRESSV = CLAMP; MAGFILTER = LINEAR; MINFILTER = LINEAR; }; sampler2D RandNormal = sampler_state { Texture = <randomTexture>; ADDRESSU = WRAP; ADDRESSV = WRAP; MAGFILTER = LINEAR; MINFILTER = LINEAR; }; float4 PixelShaderFunction(VS_OUTPUT IN) : COLOR0 { float4 samples[16] = { float4(0.355512, -0.709318, -0.102371, 0.0 ), float4(0.534186, 0.71511, -0.115167, 0.0 ), float4(-0.87866, 0.157139, -0.115167, 0.0 ), float4(0.140679, -0.475516, -0.0639818, 0.0 ), float4(-0.0796121, 0.158842, -0.677075, 0.0 ), float4(-0.0759516, -0.101676, -0.483625, 0.0 ), float4(0.12493, -0.0223423, -0.483625, 0.0 ), float4(-0.0720074, 0.243395, -0.967251, 0.0 ), float4(-0.207641, 0.414286, 0.187755, 0.0 ), float4(-0.277332, -0.371262, 0.187755, 0.0 ), float4(0.63864, -0.114214, 0.262857, 0.0 ), float4(-0.184051, 0.622119, 0.262857, 0.0 ), float4(0.110007, -0.219486, 0.435574, 0.0 ), float4(0.235085, 0.314707, 0.696918, 0.0 ), float4(-0.290012, 0.0518654, 0.522688, 0.0 ), float4(0.0975089, -0.329594, 0.609803, 0.0 ) }; IN.TexCoord.x += 1.0/1600.0; IN.TexCoord.y += 1.0/1200.0; normalize (IN.viewDirection); float depth = tex2D(depthSampler, IN.TexCoord).a; float3 se = depth * IN.viewDirection; float3 randNormal = tex2D( RandNormal, IN.TexCoord * 200.0 ).rgb; float3 normal = tex2D(depthSampler, IN.TexCoord).rgb; float finalColor = 0.0f; for (int i = 0; i < 16; i++) { float3 ray = reflect(samples[i].xyz,randNormal) * sampleRadius; //if (dot(ray, normal) < 0) // ray += normal * sampleRadius; float4 sample = float4(se + ray, 1.0f); float4 ss = mul(sample, xProjection); float2 sampleTexCoord = 0.5f * ss.xy/ss.w + float2(0.5f, 0.5f); sampleTexCoord.x += 1.0/1600.0; sampleTexCoord.y += 1.0/1200.0; float sampleDepth = tex2D(depthSampler, sampleTexCoord).a; if (sampleDepth == 1.0) { finalColor ++; } else { float occlusion = distanceScale* max(sampleDepth - depth, 0.0f); finalColor += 1.0f / (1.0f + occlusion * occlusion * 0.1); } } return float4(finalColor/16, finalColor/16, finalColor/16, 1.0f); } technique SSAO { pass P0 { VertexShader = compile vs_3_0 VertexShaderFunction(); PixelShader = compile ps_3_0 PixelShaderFunction(); } }

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  • How add fog with pixel shader (HLSL) XNA?

    - by Mehdi Bugnard
    I started to make a small game in XNA . And recently i tried to add a "fog" on "pixel shader HLSL" with the class Effect from XNA . I search online about some tutorial and found many sample. But nothing want work on my game :-( . Before i already add a "fog" effect in my game and everything work, because i used the class "BasicEffect" but with the class "Effect" and HLSL, it's really more complicated. If somebody have an idea, it's will be wonderfull. Thanks again. Here is my code HLSL, i use. // Both techniques share this same pixel shader. float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0 { //return tex2D(Sampler, input.TextureCoordinate) * input.Color; float d = length(input.TextureCoordinate - cameraPos); float l = saturate((d-fogNear)/(fogFar-fogNear)); float fogFactory = clamp((d - fogNear) / (fogFar - fogNear), 0, 1) * l; return tex2D(Sampler, input.TextureCoordinate) * lerp(input.Color, fogColor, fogFactory); } Here is the screenShot With effect Without effect

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  • Need to combine a color, mask, and sprite layer in a shader

    - by Donutz
    My task: to display a sprite using different team colors. I have a sprte graphic, part of which has to be displayed as a team color. The color isn't 'flat', i.e. it shades from brighter to darker. I can't "pre-build" the graphics because there are just too many, so I have to generate them at runtime. I've decided to use a shader, and supply it with a texture consisting of the team color, a texture consisting of a mask (black=no color, white=full color, gray=progressively dimmed color), and the sprite grapic, with the areas where the team color shows being transparent. So here's my shader code: // Effect attempts to merge a color layer, a mask layer, and a sprite layer // to produce a complete sprite sampler UnitSampler : register(s0); // the unit sampler MaskSampler : register(s1); // the mask sampler ColorSampler : register(s2); // the color float4 main(float4 color : COLOR0, float2 texCoord : TEXCOORD0) : COLOR0 { float4 tex1 = tex2D(ColorSampler, texCoord); // get the color float4 tex2 = tex2D(MaskSampler, texCoord); // get the mask float4 tex3 = tex2D(UnitSampler,texCoord); // get the unit float4 tex4 = tex1 * tex2.r * tex3; // color * mask * unit return tex4; } My problem is the calculations involving tex1 through tex4. I don't really understand how the manipulations work, so I'm just thrashing around, producing lots of different incorrect effects. So given tex1 through tex3, what calcs do I do in order to take the color (tex1), mask it (tex2), and apply the result to the unit if it's not zero? And would I be better off to make the mask just on/off (white/black) and put the color shading in the unit graphic?

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  • best way to compute vertex normals from a Triangle's list

    - by nkint
    hi i'm a complete newbie in computergraphics so sorry if it's a stupid answer. i'm trying to make a simple 3d engine from scratch, more for educational purpose than for real use. i have a Surface object with inside a Triangle's list. For now i compute normals inside Triangle class, in this way: triangle.computeFaceNormals() { Vec3D u = v1.sub(v3) Vec3D v = v1.sub(v2) Vec3D normal = Vec3D.cross(u,v) normal.normalized() this.n1 = this.n2 = this.n3 = normal } and when building surface: t = new Triangle(v1,v2,v3).computeFaceNormals() surface.addTriangle(t) and i think this is the best way to do that.. isn't it? now.. what about for vertex normals? i've found this simple algorithm: flipcode vertex normal but.. hei this algorithm has.. exponential complexity? (if my memory doesn't fail my computer science background..) (bytheway.. it has 3 nested loops.. i don't think it's the best way to do it..) any suggestion?

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  • How to get predecessor and successors from an adjacency matrix

    - by NickTFried
    Hi I am am trying to complete an assignment, where it is ok to consult the online community. I have to create a graph class that ultimately can do Breadth First Search and Depth First Search. I have been able to implement those algorithms successfully however another requirement is to be able to get the successors and predecessors and detect if two vertices are either predecessors or successors for each other. I'm having trouble thinking of a way to do this. I will post my code below, if anyone has any suggestions it would be greatly appreciated. import java.util.ArrayList; import java.util.Iterator; import java.util.LinkedList; import java.util.Queue; import java.util.Stack; public class Graph<T> { public Vertex<T> root; public ArrayList<Vertex<T>> vertices=new ArrayList<Vertex<T>>(); public int[][] adjMatrix; int size; private ArrayList<Vertex<T>> dfsArrList; private ArrayList<Vertex<T>> bfsArrList; public void setRootVertex(Vertex<T> n) { this.root=n; } public Vertex<T> getRootVertex() { return this.root; } public void addVertex(Vertex<T> n) { vertices.add(n); } public void removeVertex(int loc){ vertices.remove(loc); } public void addEdge(Vertex<T> start,Vertex<T> end) { if(adjMatrix==null) { size=vertices.size(); adjMatrix=new int[size][size]; } int startIndex=vertices.indexOf(start); int endIndex=vertices.indexOf(end); adjMatrix[startIndex][endIndex]=1; adjMatrix[endIndex][startIndex]=1; } public void removeEdge(Vertex<T> v1, Vertex<T> v2){ int startIndex=vertices.indexOf(v1); int endIndex=vertices.indexOf(v2); adjMatrix[startIndex][endIndex]=1; adjMatrix[endIndex][startIndex]=1; } public int countVertices(){ int ver = vertices.size(); return ver; } /* public boolean isPredecessor( Vertex<T> a, Vertex<T> b){ for() return true; }*/ /* public boolean isSuccessor( Vertex<T> a, Vertex<T> b){ for() return true; }*/ public void getSuccessors(Vertex<T> v1){ } public void getPredessors(Vertex<T> v1){ } private Vertex<T> getUnvisitedChildNode(Vertex<T> n) { int index=vertices.indexOf(n); int j=0; while(j<size) { if(adjMatrix[index][j]==1 && vertices.get(j).visited==false) { return vertices.get(j); } j++; } return null; } public Iterator<Vertex<T>> bfs() { Queue<Vertex<T>> q=new LinkedList<Vertex<T>>(); q.add(this.root); printVertex(this.root); root.visited=true; while(!q.isEmpty()) { Vertex<T> n=q.remove(); Vertex<T> child=null; while((child=getUnvisitedChildNode(n))!=null) { child.visited=true; bfsArrList.add(child); q.add(child); } } clearVertices(); return bfsArrList.iterator(); } public Iterator<Vertex<T>> dfs() { Stack<Vertex<T>> s=new Stack<Vertex<T>>(); s.push(this.root); root.visited=true; printVertex(root); while(!s.isEmpty()) { Vertex<T> n=s.peek(); Vertex<T> child=getUnvisitedChildNode(n); if(child!=null) { child.visited=true; dfsArrList.add(child); s.push(child); } else { s.pop(); } } clearVertices(); return dfsArrList.iterator(); } private void clearVertices() { int i=0; while(i<size) { Vertex<T> n=vertices.get(i); n.visited=false; i++; } } private void printVertex(Vertex<T> n) { System.out.print(n.label+" "); } }

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  • evaluating a code of a graph [migrated]

    - by mazen.r.f
    This is relatively a long code,if you have the tolerance and the will to find out how to make this code work then take a look please, i will appreciate your feed back. i have spent two days trying to come up with a code to represent a graph , then calculate the shortest path using dijkastra algorithm , but i am not able to get the right result , even the code runs without errors , but the result is not correct , always i am getting 0. briefly,i have three classes , Vertex, Edge, Graph , the Vertex class represents the nodes in the graph and it has id and carried ( which carry the weight of the links connected to it while using dijkastra algorithm ) and a vector of the ids belong to other nodes the path will go through before arriving to the node itself , this vector is named previous_nodes. the Edge class represents the edges in the graph it has two vertices ( one in each side ) and a wight ( the distance between the two vertices ). the Graph class represents the graph , it has two vectors one is the vertices included in this graph , and the other is the edges included in the graph. inside the class Graph there is a method its name shortest takes the sources node id and the destination and calculates the shortest path using dijkastra algorithm, and i think that it is the most important part of the code. my theory about the code is that i will create two vectors one for the vertices in the graph i will name it vertices and another vector its name is ver_out it will include the vertices out of calculation in the graph, also i will have two vectors of type Edge , one its name edges for all the edges in the graph and the other its name is track to contain temporarily the edges linked to the temporarily source node in every round , after the calculation of every round the vector track will be cleared. in main() i created five vertices and 10 edges to simulate a graph , the result of the shortest path supposedly to be 4 , but i am always getting 0 , that means i am having something wrong in my code , so if you are interesting in helping me find my mistake and how to make the code work , please take a look. the way shortest work is as follow at the beginning all the edges will be included in the vector edges , we select the edges related to the source and put them in the vector track , then we iterate through track and add the wight of every edge to the vertex (node ) related to it ( not the source vertex ) , then after we clear track and remove the source vertex from the vector vertices and select a new source , and start over again select the edges related to the new source , put them in track , iterate over edges in tack , adding the weights to the corresponding vertices then remove this vertex from the vector vertices, and clear track , and select a new source , and so on . here is the code. #include<iostream> #include<vector> #include <stdlib.h> // for rand() using namespace std; class Vertex { private: unsigned int id; // the name of the vertex unsigned int carried; // the weight a vertex may carry when calculating shortest path vector<unsigned int> previous_nodes; public: unsigned int get_id(){return id;}; unsigned int get_carried(){return carried;}; void set_id(unsigned int value) {id = value;}; void set_carried(unsigned int value) {carried = value;}; void previous_nodes_update(unsigned int val){previous_nodes.push_back(val);}; void previous_nodes_erase(unsigned int val){previous_nodes.erase(previous_nodes.begin() + val);}; Vertex(unsigned int init_val = 0, unsigned int init_carried = 0) :id (init_val), carried(init_carried) // constructor { } ~Vertex() {}; // destructor }; class Edge { private: Vertex first_vertex; // a vertex on one side of the edge Vertex second_vertex; // a vertex on the other side of the edge unsigned int weight; // the value of the edge ( or its weight ) public: unsigned int get_weight() {return weight;}; void set_weight(unsigned int value) {weight = value;}; Vertex get_ver_1(){return first_vertex;}; Vertex get_ver_2(){return second_vertex;}; void set_first_vertex(Vertex v1) {first_vertex = v1;}; void set_second_vertex(Vertex v2) {second_vertex = v2;}; Edge(const Vertex& vertex_1 = 0, const Vertex& vertex_2 = 0, unsigned int init_weight = 0) : first_vertex(vertex_1), second_vertex(vertex_2), weight(init_weight) { } ~Edge() {} ; // destructor }; class Graph { private: std::vector<Vertex> vertices; std::vector<Edge> edges; public: Graph(vector<Vertex> ver_vector, vector<Edge> edg_vector) : vertices(ver_vector), edges(edg_vector) { } ~Graph() {}; vector<Vertex> get_vertices(){return vertices;}; vector<Edge> get_edges(){return edges;}; void set_vertices(vector<Vertex> vector_value) {vertices = vector_value;}; void set_edges(vector<Edge> vector_ed_value) {edges = vector_ed_value;}; unsigned int shortest(unsigned int src, unsigned int dis) { vector<Vertex> ver_out; vector<Edge> track; for(unsigned int i = 0; i < edges.size(); ++i) { if((edges[i].get_ver_1().get_id() == vertices[src].get_id()) || (edges[i].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[i]); edges.erase(edges.begin()+i); } }; for(unsigned int i = 0; i < track.size(); ++i) { if(track[i].get_ver_1().get_id() != vertices[src].get_id()) { track[i].get_ver_1().set_carried((track[i].get_weight()) + track[i].get_ver_2().get_carried()); track[i].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else { track[i].get_ver_2().set_carried((track[i].get_weight()) + track[i].get_ver_1().get_carried()); track[i].get_ver_2().previous_nodes_update(vertices[src].get_id()); } } for(unsigned int i = 0; i < vertices.size(); ++i) if(vertices[i].get_id() == src) vertices.erase(vertices.begin() + i); // removing the sources vertex from the vertices vector ver_out.push_back (vertices[src]); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int i = 0; i < vertices.size(); ++i) if((vertices[i].get_carried() < vertices[src].get_carried()) && (vertices[i].get_id() != dis)) src = vertices[i].get_id(); //while(!edges.empty()) for(unsigned int round = 0; round < vertices.size(); ++round) { for(unsigned int k = 0; k < edges.size(); ++k) { if((edges[k].get_ver_1().get_id() == vertices[src].get_id()) || (edges[k].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[k]); edges.erase(edges.begin()+k); } }; for(unsigned int n = 0; n < track.size(); ++n) if((track[n].get_ver_1().get_id() != vertices[src].get_id()) && (track[n].get_ver_1().get_carried() > (track[n].get_ver_2().get_carried() + track[n].get_weight()))) { track[n].get_ver_1().set_carried((track[n].get_weight()) + track[n].get_ver_2().get_carried()); track[n].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else if(track[n].get_ver_2().get_carried() > (track[n].get_ver_1().get_carried() + track[n].get_weight())) { track[n].get_ver_2().set_carried((track[n].get_weight()) + track[n].get_ver_1().get_carried()); track[n].get_ver_2().previous_nodes_update(vertices[src].get_id()); } for(unsigned int t = 0; t < vertices.size(); ++t) if(vertices[t].get_id() == src) vertices.erase(vertices.begin() + t); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int tt = 0; tt < edges.size(); ++tt) { if(vertices[tt].get_carried() < vertices[src].get_carried()) { src = vertices[tt].get_id(); } } } return vertices[dis].get_carried(); } }; int main() { cout<< "Hello, This is a graph"<< endl; vector<Vertex> vers(5); vers[0].set_id(0); vers[1].set_id(1); vers[2].set_id(2); vers[3].set_id(3); vers[4].set_id(4); vector<Edge> eds(10); eds[0].set_first_vertex(vers[0]); eds[0].set_second_vertex(vers[1]); eds[0].set_weight(5); eds[1].set_first_vertex(vers[0]); eds[1].set_second_vertex(vers[2]); eds[1].set_weight(9); eds[2].set_first_vertex(vers[0]); eds[2].set_second_vertex(vers[3]); eds[2].set_weight(4); eds[3].set_first_vertex(vers[0]); eds[3].set_second_vertex(vers[4]); eds[3].set_weight(6); eds[4].set_first_vertex(vers[1]); eds[4].set_second_vertex(vers[2]); eds[4].set_weight(2); eds[5].set_first_vertex(vers[1]); eds[5].set_second_vertex(vers[3]); eds[5].set_weight(5); eds[6].set_first_vertex(vers[1]); eds[6].set_second_vertex(vers[4]); eds[6].set_weight(7); eds[7].set_first_vertex(vers[2]); eds[7].set_second_vertex(vers[3]); eds[7].set_weight(1); eds[8].set_first_vertex(vers[2]); eds[8].set_second_vertex(vers[4]); eds[8].set_weight(8); eds[9].set_first_vertex(vers[3]); eds[9].set_second_vertex(vers[4]); eds[9].set_weight(3); unsigned int path; Graph graf(vers, eds); path = graf.shortest(2, 4); cout<< path << endl; return 0; }

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  • Evaluating code for a graph [migrated]

    - by mazen.r.f
    This is relatively long code. Please take a look at this code if you are still willing to do so. I will appreciate your feedback. I have spent two days trying to come up with code to represent a graph, calculating the shortest path using Dijkstra's algorithm. But I am not able to get the right result, even though the code runs without errors. The result is not correct and I am always getting 0. I have three classes: Vertex, Edge, and Graph. The Vertex class represents the nodes in the graph and it has id and carried (which carry the weight of the links connected to it while using Dijkstra's algorithm) and a vector of the ids belong to other nodes the path will go through before arriving to the node itself. This vector is named previous_nodes. The Edge class represents the edges in the graph and has two vertices (one in each side) and a width (the distance between the two vertices). The Graph class represents the graph. It has two vectors, where one is the vertices included in this graph, and the other is the edges included in the graph. Inside the class Graph, there is a method named shortest() that takes the sources node id and the destination and calculates the shortest path using Dijkstra's algorithm. I think that it is the most important part of the code. My theory about the code is that I will create two vectors, one for the vertices in the graph named vertices, and another vector named ver_out (it will include the vertices out of calculation in the graph). I will also have two vectors of type Edge, where one is named edges (for all the edges in the graph), and the other is named track (to temporarily contain the edges linked to the temporary source node in every round). After the calculation of every round, the vector track will be cleared. In main(), I've created five vertices and 10 edges to simulate a graph. The result of the shortest path supposedly is 4, but I am always getting 0. That means I have something wrong in my code. If you are interesting in helping me find my mistake and making the code work, please take a look. The way shortest work is as follow: at the beginning, all the edges will be included in the vector edges. We select the edges related to the source and put them in the vector track, then we iterate through track and add the width of every edge to the vertex (node) related to it (not the source vertex). After that, we clear track and remove the source vertex from the vector vertices and select a new source. Then we start over again and select the edges related to the new source, put them in track, iterate over edges in track, adding the weights to the corresponding vertices, then remove this vertex from the vector vertices. Then clear track, and select a new source, and so on. #include<iostream> #include<vector> #include <stdlib.h> // for rand() using namespace std; class Vertex { private: unsigned int id; // the name of the vertex unsigned int carried; // the weight a vertex may carry when calculating shortest path vector<unsigned int> previous_nodes; public: unsigned int get_id(){return id;}; unsigned int get_carried(){return carried;}; void set_id(unsigned int value) {id = value;}; void set_carried(unsigned int value) {carried = value;}; void previous_nodes_update(unsigned int val){previous_nodes.push_back(val);}; void previous_nodes_erase(unsigned int val){previous_nodes.erase(previous_nodes.begin() + val);}; Vertex(unsigned int init_val = 0, unsigned int init_carried = 0) :id (init_val), carried(init_carried) // constructor { } ~Vertex() {}; // destructor }; class Edge { private: Vertex first_vertex; // a vertex on one side of the edge Vertex second_vertex; // a vertex on the other side of the edge unsigned int weight; // the value of the edge ( or its weight ) public: unsigned int get_weight() {return weight;}; void set_weight(unsigned int value) {weight = value;}; Vertex get_ver_1(){return first_vertex;}; Vertex get_ver_2(){return second_vertex;}; void set_first_vertex(Vertex v1) {first_vertex = v1;}; void set_second_vertex(Vertex v2) {second_vertex = v2;}; Edge(const Vertex& vertex_1 = 0, const Vertex& vertex_2 = 0, unsigned int init_weight = 0) : first_vertex(vertex_1), second_vertex(vertex_2), weight(init_weight) { } ~Edge() {} ; // destructor }; class Graph { private: std::vector<Vertex> vertices; std::vector<Edge> edges; public: Graph(vector<Vertex> ver_vector, vector<Edge> edg_vector) : vertices(ver_vector), edges(edg_vector) { } ~Graph() {}; vector<Vertex> get_vertices(){return vertices;}; vector<Edge> get_edges(){return edges;}; void set_vertices(vector<Vertex> vector_value) {vertices = vector_value;}; void set_edges(vector<Edge> vector_ed_value) {edges = vector_ed_value;}; unsigned int shortest(unsigned int src, unsigned int dis) { vector<Vertex> ver_out; vector<Edge> track; for(unsigned int i = 0; i < edges.size(); ++i) { if((edges[i].get_ver_1().get_id() == vertices[src].get_id()) || (edges[i].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[i]); edges.erase(edges.begin()+i); } }; for(unsigned int i = 0; i < track.size(); ++i) { if(track[i].get_ver_1().get_id() != vertices[src].get_id()) { track[i].get_ver_1().set_carried((track[i].get_weight()) + track[i].get_ver_2().get_carried()); track[i].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else { track[i].get_ver_2().set_carried((track[i].get_weight()) + track[i].get_ver_1().get_carried()); track[i].get_ver_2().previous_nodes_update(vertices[src].get_id()); } } for(unsigned int i = 0; i < vertices.size(); ++i) if(vertices[i].get_id() == src) vertices.erase(vertices.begin() + i); // removing the sources vertex from the vertices vector ver_out.push_back (vertices[src]); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int i = 0; i < vertices.size(); ++i) if((vertices[i].get_carried() < vertices[src].get_carried()) && (vertices[i].get_id() != dis)) src = vertices[i].get_id(); //while(!edges.empty()) for(unsigned int round = 0; round < vertices.size(); ++round) { for(unsigned int k = 0; k < edges.size(); ++k) { if((edges[k].get_ver_1().get_id() == vertices[src].get_id()) || (edges[k].get_ver_2().get_id() == vertices[src].get_id())) { track.push_back (edges[k]); edges.erase(edges.begin()+k); } }; for(unsigned int n = 0; n < track.size(); ++n) if((track[n].get_ver_1().get_id() != vertices[src].get_id()) && (track[n].get_ver_1().get_carried() > (track[n].get_ver_2().get_carried() + track[n].get_weight()))) { track[n].get_ver_1().set_carried((track[n].get_weight()) + track[n].get_ver_2().get_carried()); track[n].get_ver_1().previous_nodes_update(vertices[src].get_id()); } else if(track[n].get_ver_2().get_carried() > (track[n].get_ver_1().get_carried() + track[n].get_weight())) { track[n].get_ver_2().set_carried((track[n].get_weight()) + track[n].get_ver_1().get_carried()); track[n].get_ver_2().previous_nodes_update(vertices[src].get_id()); } for(unsigned int t = 0; t < vertices.size(); ++t) if(vertices[t].get_id() == src) vertices.erase(vertices.begin() + t); track.clear(); if(vertices[0].get_id() != dis) {src = vertices[0].get_id();} else {src = vertices[1].get_id();} for(unsigned int tt = 0; tt < edges.size(); ++tt) { if(vertices[tt].get_carried() < vertices[src].get_carried()) { src = vertices[tt].get_id(); } } } return vertices[dis].get_carried(); } }; int main() { cout<< "Hello, This is a graph"<< endl; vector<Vertex> vers(5); vers[0].set_id(0); vers[1].set_id(1); vers[2].set_id(2); vers[3].set_id(3); vers[4].set_id(4); vector<Edge> eds(10); eds[0].set_first_vertex(vers[0]); eds[0].set_second_vertex(vers[1]); eds[0].set_weight(5); eds[1].set_first_vertex(vers[0]); eds[1].set_second_vertex(vers[2]); eds[1].set_weight(9); eds[2].set_first_vertex(vers[0]); eds[2].set_second_vertex(vers[3]); eds[2].set_weight(4); eds[3].set_first_vertex(vers[0]); eds[3].set_second_vertex(vers[4]); eds[3].set_weight(6); eds[4].set_first_vertex(vers[1]); eds[4].set_second_vertex(vers[2]); eds[4].set_weight(2); eds[5].set_first_vertex(vers[1]); eds[5].set_second_vertex(vers[3]); eds[5].set_weight(5); eds[6].set_first_vertex(vers[1]); eds[6].set_second_vertex(vers[4]); eds[6].set_weight(7); eds[7].set_first_vertex(vers[2]); eds[7].set_second_vertex(vers[3]); eds[7].set_weight(1); eds[8].set_first_vertex(vers[2]); eds[8].set_second_vertex(vers[4]); eds[8].set_weight(8); eds[9].set_first_vertex(vers[3]); eds[9].set_second_vertex(vers[4]); eds[9].set_weight(3); unsigned int path; Graph graf(vers, eds); path = graf.shortest(2, 4); cout<< path << endl; return 0; }

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  • Modern Shader Book?

    - by Michael Stum
    I'm interested in learning about Shaders: What are they, when/for what would I use them, and how to use them. (Specifically I'm interested in Water and Bloom effects, but I know close to 0 about Shaders, so I need a general introduction). I saw a lot of books that are a couple of years old, so I don't know if they still apply. I'm targeting XNA 4.0 at the moment (which I believe means HLSL Shaders for Shader Model 4.0), but anything that generally targets DirectX 11 and OpenGL 4 is helpful I guess.

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  • XNA Shader Texture Memory

    - by Alex
    I was wondering about texture optimization in XNA 4.0. Will the the contentmanager send the texturedata to the GPU directly when the texture gets loaded or do I send the texture data to the GPU when I declare a texture in my shader. If that's the case, what happens if I have 5 shaders all using the same texture, does that mean that I send 5 instances of that texture data to the gpu or am I simply telling the GPU what preloaded texture to use? Or does XNA do the heavy lifting in the background?

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  • Wine shader model 3.0 not detected

    - by LillyPopper
    I am trying to run eve off the latest version of wine. It was running just fine yesterday, now I go to start it and it tells me that I need shader model version 3.0. I followed this guide here for setting up wine: http://www.unixmen.com/install-and-configure-wine-to-play-latest-windows-games-in-linux-ubuntu-linuxmint-fedora/ I used a shortcut with the following command: wine "/media/gibbo/Games/EVE/eve.exe" Now it just seems to not work...after it was before Any ideas?

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  • OpenGL quake 3 shader file for objects (for trees)

    - by mlodziaszka
    I decided to add to my game few trees, I already quake 3 model loader (md3) its for characters and method for texture drawing is store in *.ini file. I found a package of trees in MD3 and I have no problem with loading model alone, but there is a *.shader file and i have no idea how to load it to draw texture properly. Tree pack: http://www.custommapmakers.org/wiki/index.php/Models:GR_Trees_set I do not have to use exactly this format, I can write another loader, but trees in *.obj or .3ds look even harder

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  • XNA .FBX Vertex Color Missing

    - by Alex
    When I vertex paint and export my models from Blender (or Maya) for use in my XNA 4.0 project, I somehow lose the vertex color channel for the model. I use no custom model object or content pipelines and my own shader throws me the error: The current vertex declaration does not include all the elements required by the current vertex shader. Color0 is missing. I tryed to reopen the model in other modeling tools and the vertex colors are there. What could cause the vertex color channel to not get loaded in XNA 4.0? Here's a temporary link to the FBX file(server refuses to send a fbx, so rename the .jpg file to .fbx after downloading) http://resources.gamestack.org/BananaBush.jpg

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  • Using DynamicVertexBuffer in XNA 4.0

    - by Bevin
    I read about DynamicVertexBuffer, and how it's supposed to be better for data that changes often. I have a world built up by cubes, and I need to store the cubes' vertices in this buffer to draw them to the screen. However, not all cubes have vertices (some are air, which is transparent) and not all faces of the cubes need to be drawn either (they are facing each other), so how do I keep track of what vertices are stored where in the buffer? Also, certain faces need to be drawn last, namely the ones with transparency in them (like glass or leaves), and these faces also need to be drawn in a back-to-front order to not mess up the alpha blending. If all of these vertices are stored arbitrarily in this buffer, how do I know what vertices are where? Also, the number of vertices can change, but the DynamicVertexBuffer doesn't seem very dynamic to me, since I can't change it's size at all. Do I have to recreate the buffer every time I need to add or remove faces?

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  • Problems implementing a screen space shadow ray tracing shader

    - by Grieverheart
    Here I previously asked for the possibility of ray tracing shadows in screen space in a deferred shader. Several problems were pointed out. One of the most important problem is that only visible objects can cast shadows and objects between the camera and the shadow caster can interfere. Still I thought it'd be a fun experiment. The idea is to calculate the view coordinates of pixels and cast a ray to the light. The ray is then traced pixel by pixel to the light and its depth is compared with the depth at the pixel. If a pixel is in front of the ray, a shadow is casted at the original pixel. At first I thought that I could use the DDA algorithm in 2D to calculate the distance 't' (in p = o + t d, where o origin, d direction) to the next pixel and use it in the 3D ray equation to find the ray's z coordinate at that pixel's position. For the 2D ray, I would use the projected and biased 3D ray direction and origin. The idea was that 't' would be the same in both 2D and 3D equations. Unfortunately, this is not the case since the projection matrix is 4D. Thus, some tweak needs to be done to make this work this way. I would like to ask if someone knows of a way to do what I described above, i.e. from a 2D ray in texture coordinate space to get the 3D ray in screen space. I did implement a simple version of the idea which you can see in the following video: video here Shadows may seem a bit pixelated, but that's mostly because of the size of the step in 't' I chose. And here is the shader: #version 330 core uniform sampler2D DepthMap; uniform vec2 projAB; uniform mat4 projectionMatrix; const vec3 light_p = vec3(-30.0, 30.0, -10.0); noperspective in vec2 pass_TexCoord; smooth in vec3 viewRay; layout(location = 0) out float out_AO; vec3 CalcPosition(void){ float depth = texture(DepthMap, pass_TexCoord).r; float linearDepth = projAB.y / (depth - projAB.x); vec3 ray = normalize(viewRay); ray = ray / ray.z; return linearDepth * ray; } void main(void){ vec3 origin = CalcPosition(); if(origin.z < -60) discard; vec2 pixOrigin = pass_TexCoord; //tex coords vec3 dir = normalize(light_p - origin); vec2 texel_size = vec2(1.0 / 600.0); float t = 0.1; ivec2 pixIndex = ivec2(pixOrigin / texel_size); out_AO = 1.0; while(true){ vec3 ray = origin + t * dir; vec4 temp = projectionMatrix * vec4(ray, 1.0); vec2 texCoord = (temp.xy / temp.w) * 0.5 + 0.5; ivec2 newIndex = ivec2(texCoord / texel_size); if(newIndex != pixIndex){ float depth = texture(DepthMap, texCoord).r; float linearDepth = projAB.y / (depth - projAB.x); if(linearDepth > ray.z + 0.1){ out_AO = 0.2; break; } pixIndex = newIndex; } t += 0.5; if(texCoord.x < 0 || texCoord.x > 1.0 || texCoord.y < 0 || texCoord.y > 1.0) break; } } As you can see, here I just increment 't' by some arbitrary factor, calculate the 3D ray and project it to get the pixel coordinates, which is not really optimal. Hopefully, I would like to optimize the code as much as possible and compare it with shadow mapping and how it scales with the number of lights. PS: Keep in mind that I reconstruct position from depth by interpolating rays through a full screen quad.

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  • Safe way for getting/finding a vertex in a graph with custom properties -> good programming practice

    - by Shadow
    Hi, I am writing a Graph-class using boost-graph-library. I use custom vertex and edge properties and a map to store/find the vertices/edges for a given property. I'm satisfied with how it works, so far. However, I have a small problem, where I'm not sure how to solve it "nicely". The class provides a method Vertex getVertex(Vertexproperties v_prop) and a method bool hasVertex(Vertexproperties v_prop) The question now is, would you judge this as good programming practice in C++? My opinion is, that I have first to check if something is available before I can get it. So, before getting a vertex with a desired property, one has to check if hasVertex() would return true for those properties. However, I would like to make getVertex() a bit more robust. ATM it will segfault when one would directly call getVertex() without prior checking if the graph has a corresponding vertex. A first idea was to return a NULL-pointer or a pointer that points past the last stored vertex. For the latter, I haven't found out how to do this. But even with this "robust" version, one would have to check for correctness after getting a vertex or one would also run into a SegFault when dereferencing that vertex-pointer for example. Therefore I am wondering if it is "ok" to let getVertex() SegFault if one does not check for availability beforehand?

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  • Billboard shader without distortion

    - by Nick Wiggill
    I use the standard approach to billboarding within Unity that is OK, but not ideal: transform.LookAt(camera). The problem is that this introduces distortion toward the edges of the viewport, especially as the field of view angle grows larger. This is unlike the perfect billboarding you'd see in eg. Doom when seeing an enemy from any angle and irrespective of where they are located in screen space. Obviously, there are ways to blit an image directly to the viewport, centred around a single vertex, but I'm not hot on shaders. Does anyone have any samples of this approach (GLSL if possible), or any suggestions as to why it isn't typically done this way (vs. the aforementioned quad transformation method)? EDIT: I was confused, thanks Nathan for the heads up. Of course, Causing the quads to look at the camera does not cause them to be parallel to the view plane -- which is what I need.

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  • assigning values to shader parameters in the XNA content pipeline

    - by Nick
    I have tried creating a simple content processor that assigns the custom effect I created to models instead of the default BasicEffect. [ContentProcessor(DisplayName = "Shadow Mapping Model")] public class ShadowMappingModelProcessor : ModelProcessor { protected override MaterialContent ConvertMaterial(MaterialContent material, ContentProcessorContext context) { EffectMaterialContent shadowMappingMaterial = new EffectMaterialContent(); shadowMappingMaterial.Effect = new ExternalReference<EffectContent>("Effects/MultipassShadowMapping.fx"); return context.Convert<MaterialContent, MaterialContent>(shadowMappingMaterial, typeof(MaterialProcessor).Name); } } This works, but when I go to draw a model in a game, the effect has no material properties assigned. How would I go about assigning, say, my DiffuseColor or SpecularColor shader parameter to white or (better) can I assign it to some value specified by the artist in the model? (I think this may have something to do with the OpaqueDataDictionary but I am confused on how to use it--the content pipeline has always been a black box to me.)

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  • Shader inputs in a general purpose engine

    - by dreta
    I'm not familiar with SDKs like Unity or UDK that much, so i can't check this offhand. Do general purpose engines allow users to create custom uniform variables? The way i see it, and the way i have implemented it in an engine i'm writing to learn 3D, is that there is a "set" of uniforms provided by the engine and if you want to write a custom shader then you utilize uniforms you need to create a wanted effect. Now, the thing is, first of all i'm not an artist, second of all, i didn't have a chance to create complex scenes yet. So my question is, is it common practice to define variables that the engine provides and only allow the user to work with what they're given? Allowing users to add custom programs and use them where they want is not hard, but i have issues imagining how you'd go about doing the same for uniforms.

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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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  • 3d vertex translated onto 2d viewport

    - by Dan Leidal
    I have a spherical world defined by simple trigonometric functions to create triangles that are relatively similar in size and shape throughout. What I want to be able to do is use mouse input to target a range of vertices in the area around the mouse click in order to manipulate these vertices in real time. I read a post on this forum regarding translating 3d world coordinates into the 2d viewport.. it recommended that you should multiply the world vector coordinates by the viewport and then the projection, but they didn't include any code examples, and suffice to say i couldn't get any good results. Further information.. I am using a lookat method for the viewport. Does this cause a problem, and if so is there a solution? If this isn't the problem, does anyone have a simple code example illustrating translating one vertex in a 3d world into a 2d viewspace? I am using XNA.

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