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Kilian Laudt

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About Kilian Laudt

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  1. Hi, I took a look at the code you posted and I'm not 100% sure if I can do what I want with it.  I have a fullscreenquad with my depth texture on it and my shader should calculate normals in view space on it. Therefore I need to calculate the view space position of my current fragment and the neighboring fragments.  As far as I unterstand the code above it's only possible for the current fragment. Or am I wrong?
  2.   I tried my own approach of a derivative to see if it changes anything. I now put it back to the original code from the slides   What this code does is sample neighbouring texels. So if you have a non-square texture then replace float2(texelSize, 0) with float2(1.0 / texSizeX, 0) and replace float2(0, texelSize) with float2(0, 1.0 / texSizeY). Allright, I figured that out but even if I'm using not the correct texelSize i figure it's not the cause of my problem. But I will fix this now.   It's a 32-bit target (called Ogre::PF_FLOAT32_R)     Yeah, it's float3 posEye = uvToEye(input.texco, depth, invProj_m);  Dont know why it's not in my original post, It's definitively in my program  
  3. double post, can't find a button to delete it..
  4. Hey, I just came a little bit further using the code in my first post. It turned out I gave a wrong inverted projection matrix. I fixed that, I guess. At least my screen isn't black anymore :-D This is what it looks like: http://img221.imageshack.us/img221/8892/closeupr.png http://img833.imageshack.us/img833/7654/wrongnormals.png   My guess is there is something wrong with my depth texture. When I view it, all the spheres are just white except when I come really close. That would explain why my normals are black inside the spheres. There is no difference in the depth, so my derivatives will be zero and so will be the calculated normal.   I don't think that I want to let the normals face the light. I just want to have the normals on my spheres so I can use them and their position to shade the surface.   Regards, Kilian
  5. Thanks for your advice. I will definitly look into it. Regards, Kilian   Edit: You recommended: float texelSize = 1.0 / textureSize; //eg: 1.0 / 1024.0   What should I do if my texture is not square?
  6. Hello, I'm trying to implement Nvidias Screen Space Fluid Rendering in Ogre using Direct3D9 as my rendering system. (http://developer.download.nvidia.com/presentations/2010/gdc/Direct3D_Effects.pdf for slides and https://www.google.de/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDoQFjAA&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.,d.Yms for paper).   I got my billboard quad particles and using a shader they look like spheres. I save the depth from those spheres in a texture. At the next step I have to blur the depth. Now I put this blurred texture on a screen filling quad and let the next shader run on it. Now I have to create the normals at this point. To get the normals I have to calculate the view-space coordinates from the depth and texture coordinates (see slide 18).   My problem is the mysterious uvToEye-function.   I found some code to recalculate the coordinates here: http://mynameismjp.wordpress.com/2009/03/10/reconstructing-position-from-depth/ but it doesn't work (all I seem to get is (0,0,0) for every point).   This is my code: I skipped the blur-step since I figured there is no need to blur the depth before I cant calculate normals from it.   My vertex shader for depth and making the billboardquads spherical: struct VertexIn { float4 pos : POSITION; float2 texco : TEXCOORD0; }; struct VertexOut { float4 pos : POSITION; float2 texco : TEXCOORD0; float3 eyeSpacePos : TEXCOORD1; }; struct PixelInput { float2 texco : TEXCOORD0; float3 eyeSpacePos : TEXCOORD1; }; struct PixelOutput { float4 color : COLOR0; }; VertexOut mainVS( VertexIn input, uniform float4x4 worldViewProj_m, uniform float4x4 worldView_m, uniform float sphereRadius ) { VertexOut output = (VertexOut)0; input.pos.y += sphereRadius; //partikel nicht im Boden versinken lassen output.pos = mul( worldViewProj_m, input.pos ); output.texco = input.texco; output.eyeSpacePos = mul(worldView_m, input.pos).xyz; return output; } PixelOutput mainPS(PixelInput input, uniform float4x4 projMatrix, uniform float sphereRadius ) { PixelOutput output = (PixelOutput)0; // calculate eye-space sphere normal from texture coordinates float3 N; N.xy = input.texco*2.0-1.0; float r2 = dot(N.xy, N.xy); if (r2 > 1.0) discard; // kill pixels outside circle N.z = sqrt(1.0 - r2); // calculate depth float4 pixelPos = float4(input.eyeSpacePos + N*sphereRadius, 1.0); //approximation of a sphere float4 clipSpacePos = mul(projMatrix,pixelPos); float fragDepth = clipSpacePos.z / clipSpacePos.w; output.color.r = fragDepth; return output; }   And this is my shader for calculating the normals: struct VertexIn { float4 pos : POSITION; float2 texco : TEXCOORD0; }; struct VertexOut { float4 pos : POSITION; float2 texco : TEXCOORD0; }; struct PixelInput { float2 texco : TEXCOORD0; }; struct PixelOutput { float4 color : COLOR0; }; VertexOut mainVS(VertexIn input, uniform float4x4 worldViewProj_m) { VertexOut output = (VertexOut)0; output.pos = mul( worldViewProj_m, input.pos ); output.texco = input.texco; return output; } float3 uvToEye(float2 texCoord, float depth, float4x4 iP_m){ // Get x/w and y/w from the viewport position float x = texCoord.x * 2.0 - 1.0; float y = (1 - texCoord.y) * 2.0 - 1.0; //float y = texCoord.y * 2.0 - 1.0; float4 clipPos = float4(x , y, depth, 1.0f); // Transform by the inverse projection matrix //float4 viewPos = mul(clipPos, iP_m); float4 viewPos = mul(iP_m , clipPos); // Divide by w to get the view-space position return viewPos.xyz / viewPos.w; } PixelOutput mainPS(PixelInput input, uniform sampler depthTex: register(s0), uniform float4x4 invProj_m) { PixelOutput output = (PixelOutput)0; // read eye-space depth from texture float depth = tex2D(depthTex, input.texco).r; // calculate eye-space position from depth float texelSize = 0.0001; // correct value? // calculate differences float3 ddx1 = uvToEye(input.texco + float2(texelSize, 0), tex2D(depthTex, input.texco + float2(texelSize, 0)).r, invProj_m) - posEye; float3 ddx2 = posEye - uvToEye(input.texco + float2(-texelSize, 0), tex2D(depthTex, input.texco + float2(-texelSize, 0)).r, invProj_m); ddx1 = -ddx2 + ddx1; if (abs(ddx1.z) > abs(ddx2.z)) { ddx1 = ddx2; } float3 ddy1 = uvToEye(input.texco + float2(0, texelSize), tex2D(depthTex, input.texco + float2(0, texelSize)).r, invProj_m) - posEye; float3 ddy2 = posEye - uvToEye(input.texco + float2(0, -texelSize), tex2D(depthTex, input.texco + float2(0, -texelSize)).r, invProj_m); ddy1 = -ddy2 + ddy1; if (abs(ddy2.z) < abs(ddy1.z)) { ddy1 = ddy2; } // calculate normal float3 n = cross(ddx1, ddy1); n = normalize(n); //output.color = float4(posEye, 1.0); // for testing, results in a black screen output.color = float4(n,1); return output; } I hope someone here can tell me what I'm doing wrong and what is the right way to do it. Regards, Kilian  
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