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Daniel Wilson

Member Since 31 May 2012
Offline Last Active Aug 26 2012 04:16 PM

Posts I've Made

In Topic: Tool to mathematically create a mesh

26 August 2012 - 04:17 PM

I've only played with this on linux, but seems to fit your description the most: http://k3dsurf.sourceforge.net/

That's what I needed thanks!

In Topic: What to do with an attenuated light vector in my shader

17 August 2012 - 01:12 PM

So I've been working on this a while longer, and the only real conclusion I have come up with is the colour values must be wrong. I thought for a while maybe they were right and I was not doing the correct thing with the result. I was given the good advice that:

The scattered radiance should be added to the phong radiance component because
the phong model computes the radiance at the surface only, the scattered radiance is
just more radiance coming from under the surface, to the eye.

So hopefully that might help some future googlers, now if if I could just work out the correct values to begin with! I knew the colours were too trippy Posted Image

In Topic: How to change colour based on viewing angle

14 August 2012 - 07:54 AM

Very nice thanks for that cool answer, the effect is simple works well for my purposes!

In Topic: What to do with an attenuated light vector in my shader

07 August 2012 - 09:29 PM

Yeah should've mentioned that too sorry, I am certain that data is correct. This shader is actually being used in Ogre, and it's easy to generate the texture in Ogre and the output is virtually identical to fx composer. Each rgba component in the floating point texture just holds a preset scattering coefficient value taken from this table:
Posted Image

In Topic: What to do with an attenuated light vector in my shader

07 August 2012 - 12:33 PM

Woops sorry, I've gotten so deep into this thing I'm just assuming the whole world knows what I mean by p_omega_out Posted Image. I appreciate the help and even general advice is very useful. Here is another screen from the paper which should be looked at with the image from the first post.
Posted Image
When I say p_omega_out, I mean the vector from the pixel P to the viewer.

Here is the fx composer file I have at the moment, it's rather large and based off of the algorithms in the paper which you would probably need to read in full to make sense of so I won't ask you to do that! I am applying this map as the subsurface texture map.

[source lang="java"]/*****************************************************************//*** HOST APPLICATION IDENTIFIERS ********************************//*** Potentially predefined by varying host environments *********//*****************************************************************/// #define _XSI_ /* predefined when running in XSI */// #define TORQUE /* predefined in TGEA 1.7 and up */// #define _3DSMAX_ /* predefined in 3DS Max */#ifdef _3DSMAX_int ParamID = 0x0003; /* Used by Max to select the correct parser */#endif /* _3DSMAX_ */#ifdef _XSI_#define Main Static /* Technique name used for export to XNA */#endif /* _XSI_ */#ifndef FXCOMPOSER_VERSION /* for very old versions */#define FXCOMPOSER_VERSION 180#endif /* FXCOMPOSER_VERSION */#ifndef DIRECT3D_VERSION#define DIRECT3D_VERSION 0x900#endif /* DIRECT3D_VERSION */#define FLIP_TEXTURE_Y /* Different in OpenGL & DirectX *//*****************************************************************//*** EFFECT-SPECIFIC CODE BEGINS HERE ****************************//*****************************************************************//******* Lighting Macros *******//** To use "Object-Space" lighting definitions, change these two macros: **/#define LIGHT_COORDS "World"// #define OBJECT_SPACE_LIGHTS /* Define if LIGHT_COORDS is "Object" *//**** UNTWEAKABLES: Hidden & Automatically-Tracked Parameters **********/// transform object vertices to world-space:float4x4 gWorldXf : World < string UIWidget="None"; >;// transform object vertices to view space and project them in perspective:float4x4 gWvpXf : WorldViewProjection < string UIWidget="None"; >;// Ambient Lightfloat4 ambient : AMBIENT < string UIName = "Ambient Light Color"; string UIWidget = "Color";> = {0.7f,0.7f,0.7f,1.0f};// surface colorfloat4 diffuse : DIFFUSE < string UIName = "Diffuse Color"; string UIWidget = "Color";> = {0.9f,0.9f,0.9f,1.0f};float4 specular < string UIName = "Specular Color"; string UIWidget = "color";> = {0.75,0.75,0.75,1};float specularPower < string UIName = "Phong Exponent"; string UIWidget = "slider"; float UIMin = 1.0f; float UIStep = 4; float UIMax = 256.0f;> = 8.0;/*********** TEXTURES ***************/texture gColorTexture : DIFFUSE < string ResourceName = "grey.jpg"; string UIName = "Color Texture"; string ResourceType = "2D";>;sampler2D cm = sampler_state { Texture = <gColorTexture>;#if DIRECT3D_VERSION >= 0xa00 Filter = MIN_MAG_MIP_LINEAR;#else /* DIRECT3D_VERSION < 0xa00 */ MinFilter = Linear; MipFilter = Linear; MagFilter = Linear;#endif /* DIRECT3D_VERSION */ AddressU = Wrap; AddressV = Wrap;};texture gReliefTexture < string ResourceName = "SSTM.png"; string UIName = "SSTM"; string ResourceType = "2D";>;sampler2D sstm = sampler_state { Texture = <gReliefTexture>;#if DIRECT3D_VERSION >= 0xa00 Filter = MIN_MAG_MIP_LINEAR;#else /* DIRECT3D_VERSION < 0xa00 */ MinFilter = Linear; MipFilter = Linear; MagFilter = Linear;#endif /* DIRECT3D_VERSION */ AddressU = Wrap; AddressV = Wrap;};texture gNormalTexture : NORMAL < string ResourceName = "grey.jpg"; string UIName = "Normal Texture"; string ResourceType = "2D";>;sampler2D nm = sampler_state { Texture = <gNormalTexture>;#if DIRECT3D_VERSION >= 0xa00 Filter = MIN_MAG_MIP_LINEAR;#else /* DIRECT3D_VERSION < 0xa00 */ MinFilter = Linear; MipFilter = Linear; MagFilter = Linear;#endif /* DIRECT3D_VERSION */ AddressU = Wrap; AddressV = Wrap;};texture gMatrixTex < string ResourceName = "grey.jpg"; string UIName = "Matrix Texture"; string ResourceType = "1D";>;sampler1D matrix_tex = sampler_state { Texture = <gMatrixTex>;};float3x3 matTangent;float3 worldEyePos : CAMERAPOSITION;static const float AmbientIntensity = 1.0f; // The intensity of the ambient light.static const float DiffuseIntensity = 1.0f; // The intensity of the diffuse light.static const float SpecularIntensity = 1.0f; // The intensity of the specular light./********** CONNECTOR STRUCTURES *****************/struct a2v //Application to a vertex{ float4 pos : POSITION0; float3 normal : NORMAL;float4 tangent : TANGENT0;float4 binormal : BINORMAL0; float2 texcoord : TEXCOORD0;float3 NSp : TEXCOORD1;};struct v2f //Vertex to a fragment (vertex output){ float4 hpos : POSITION0; //For rasterizer (not available in fragment shader, but must be written to) float2 texcoord : TEXCOORD0; float3 oNSp : TEXCOORD1; float4 tangent : TEXCOORD2; float3 eye : TEXCOORD3; float3 worldLightDir : TEXCOORD4; float4 binormal : TEXCOORD5; float3 normal : TEXCOORD6; float3 oPosition : TEXCOORD7; float3 tangentSpaceEye : TEXCOORD8; float3 tangentSpaceLightDir : TEXCOORD9;};struct outPixel{ float4 colour : COLOR0;};/*** SHADER FUNCTIONS **********************************************/v2f view_spaceVS(a2v IN,uniform float4x4 WorldXf,uniform float4x4 WvpXf) { // invert matrixes for FX Composer WvpXf = transpose(WvpXf); WorldXf = transpose(WorldXf); v2f OUT = (v2f)0; // vertex position in homogeneous clip space OUT.hpos=mul(WvpXf, IN.pos); OUT.texcoord = IN.texcoord; // View vector in world space float3 worldPos = mul(WorldXf, IN.pos).xyz; OUT.eye = normalize(worldEyePos - worldPos); //Vertex to the eye (as opposed to incident eye->vert) // Directional light so just normalize once OUT.worldLightDir = normalize(float3(0, -1, 0)); // Planar approximation in world space float4 N = float4(0, 1, 0, 0); float4 B = float4(0, 0, 1, 0); float4 T = float4(1, 0, 0, 0); OUT.oNSp = mul(WorldXf, N); //Position in world space OUT.oPosition = worldPos; //T, B, N in world space OUT.normal = mul(WorldXf, N); OUT.tangent = mul(WorldXf, T); OUT.binormal = mul(WorldXf, B); matTangent[0] = OUT.tangent; matTangent[1] = OUT.binormal; matTangent[2] = OUT.normal; OUT.tangentSpaceEye = normalize(mul(OUT.eye, matTangent)); OUT.tangentSpaceLightDir = normalize(mul(-OUT.worldLightDir, matTangent)); return OUT;}//--------------------------float4 color_mapping(v2f IN, in float3 p_omega_out, in float4 ambient, in float4 diffuse, in float4 specular, in float specularPower, in sampler2D color_map : register(s0), in sampler2D sstm : register(s1), in sampler2D nm : register(s3)){ float3 BumpNormal = tex2D(nm, IN.texcoord)*2.0 - 1.0; float4 amb = AmbientIntensity * ambient; float4 diff = DiffuseIntensity * float4(p_omega_out, 1) * saturate(dot(IN.tangentSpaceLightDir,BumpNormal)); float3 R = normalize(2.0 * dot(BumpNormal, IN.tangentSpaceLightDir) * BumpNormal - IN.tangentSpaceLightDir); float3 v = normalize(IN.tangentSpaceEye); float spec = pow(saturate(dot(R,v)), specularPower) * SpecularIntensity; // compute final color float4 color = tex2D(color_map,IN.texcoord); float4 finalcolor = (amb + diff + spec) * color; //Remove this line to display p_omega_out with the diffuse and normal map //----------------------------------- finalcolor = float4(p_omega_out, 1.0); //----------------------------------- return finalcolor;}//--------------------------float FindLayer(in float depthM, in float2 umvm, in sampler2D sstm : register(s1) ){float4 ss_val = tex2Dlod(sstm, float4(umvm.x, umvm.y, 0, 1));float layer = 0;//Check red first, if depth is < red, layer = 0//If and only if depth is greater than red, check if depth < green -> layer = 1if(-depthM > ss_val.x){ if(-depthM > ss_val.y) { layer = 1; if(-depthM > ss_val.z) { layer = 2; } }}//if(depthM > ss_val.w){layer = 3;}return layer;}//--------------------------float4 LayerThickness(in float3 m, in float2 umvm, in sampler2D sstm : register(s1) ){float4 ss_val = tex2Dlod(sstm, float4(umvm.x, umvm.y, 0, 1));return ss_val/4.0; //Divided by 4 because (1,0,0,0) = 1/4 red, (1, 1, 1, 1) = 0.25 + 0.25 + 0.25 + 0.25 = the full depth of 1}//--------------------------float3 ReducedIntensity(in float3 p, in float3 m, in float3 lightdir, in sampler2D sstm : register(s1), in float3 normal, in float2 umvm, in float i, in float3 PM_max, in float2 upvp, in float4 tangent, in float4 binormal, in float3 NSp, in float3 diffuse, in float num_samplesF ){//L_ri(M, Omega_in)float3 finalLightVector = float3(0, 0, 0);float AttenuationKM = 1.0;//Obtain a planar surface approximation for the current m depth [light and m in view space]//light position - mfloat3 omega_in = normalize(float3(0, 1, 0) - m);float3 Nm = ((i*normal)+((num_samplesF - i)*NSp))/num_samplesF;float3 Pm = ((i*PM_max) + ((num_samplesF - i)*p))/num_samplesF;//Nm = normalize(Nm);//Pm = normalize(Pm);float cosTheta = cos(dot(Nm, omega_in));//Calculate the distance ||KM||float KM = length(dot((Pm*m),Nm))/cosTheta;//Compute the thickness of the layers at the point M, lookup SSTMfloat4 thicknessLayersM = LayerThickness(m, umvm, sstm);//Compute the thickness of the layers at the point Kfloat3 K = m + (KM*-omega_in); //SWAPPED to go back up to Kfloat3 PK = K - p; //PK 0 first time round, p ad K are the samefloat2 ukvk = (0,0);ukvk.x = upvp.x + dot(PK, tangent.xyz);ukvk.y = upvp.y + dot(PK, binormal.xyz);//ukvk = normalize(ukvk);float4 thicknessLayersK = LayerThickness(K, ukvk, sstm);//Average thicknessesfloat4 thicknessAverage = 0.5*(thicknessLayersM + thicknessLayersK);float sigmaX = ((thicknessLayersM.x - thicknessLayersK.x)/2.0)/cosTheta;float sigmaY = ((thicknessLayersM.y - thicknessLayersK.y)/2.0)/cosTheta;float sigmaZ = ((thicknessLayersM.z - thicknessLayersK.z)/2.0)/cosTheta;float sigmaW = ((thicknessLayersM.w - thicknessLayersK.w)/2.0)/cosTheta;float sigmaTotal = sigmaX+sigmaY+sigmaZ+sigmaW;float d1,d2,d3,d4;d1 = min(KM - sigmaTotal, thicknessAverage.x/cosTheta);d2 = min(KM - sigmaTotal, thicknessAverage.y/cosTheta);d3 = min(KM - sigmaTotal, thicknessAverage.z/cosTheta);d4 = min(KM - sigmaTotal, thicknessAverage.w/cosTheta);//Calculate the attenuation along KM:float att_1, att_2, att_3, att_4;att_1 = exp(-2.6 * d1);att_2 = exp(-6.6 * d2);att_3 = exp(-1.5 * d3);att_4 = exp(-1.0 * d4); //TODO: Make not HARD CODED! [img]http://public.gamedev.net//public/style_emoticons/default/ohmy.png[/img]AttenuationKM = att_1*att_2*att_3*att_4;//Estimate the reduced intensity, light position - kfloat3 omega_in_k = float3(0, 1, 0) - K;finalLightVector = omega_in_k*AttenuationKM;return finalLightVector;}//--------------------------float PhaseFunction(float g, float theta){float pTheta = (1.0-(g*g))/4.0*3.14*(1.0+g*cos(theta))*(1.0+g*cos(theta));return pTheta;}//--------------------------/************ PIXEL SHADER ******************/float4 pixel_shader(v2f IN, uniform float specularPower, uniform float4 ambient, uniform float4 diffuse, uniform float4 specular, uniform sampler2D cm, //diffuse color map uniform sampler2D sstm, //Subsurface Texture uniform sampler1D matrix_tex, //Floating Point texture containing scattering coefficients uniform sampler2D nm //Normal map, not needed) : COLOR0{float3 p = IN.oPosition; //The pixel position in world spacefloat num_samplesF = 50.0f;//Omega out is the view vector to the pointfloat3 omega_out = IN.eye; //The view vector in world space//L(P, Omega_out) The lighting contribution vector from point Pfloat3 p_omega_out = float3(0,0,0);float AttenuationPM = 1.0;float Depth_max = 1.0;float3 M_max = p - ((Depth_max/dot(IN.oNSp, omega_out))*omega_out);float3 PM_max = M_max - p;float3 PMstep = PM_max/num_samplesF;float tan = dot(PM_max, IN.tangent.xyz);float bi = dot(PM_max, IN.binormal.xyz);float2 dsdt = float2(tan, bi); //normalize(IN.eye.xy);float2 texCoordStep = float2(dsdt.x/num_samplesF, dsdt.y/num_samplesF);float2 umvm = IN.texcoord.xy;float depthM = 0;float depthStep = dot(PMstep, IN.normal); //This needs to be a value between 0-1float3 m = p; //M starts of as the point p and increases in depthfloat theta = dot(IN.worldLightDir.xyz, omega_out);//The angle between the light vector and the eye vectorfloat currentLayer = 0;float3 reducedIntensity;float4 mScattering; //Check thisfloat4 currentLayerCoeffs_S, currentLayerCoeffs_T;float currentLayerCoeffs_g; //RGBA = S-T-g-Blankfloat3 myTest;for(int i = 0; i < num_samplesF; i++){ float iF = i; //Point M localization currentLayer = FindLayer(depthM, umvm, sstm); //Returns a value between 0 and 3 //Estimate the reduced intensity - L_ri(M, omega_in) reducedIntensity = ReducedIntensity(p, m, IN.worldLightDir.xyz, sstm, IN.normal.xyz, umvm, iF, PM_max, IN.texcoord, IN.tangent, IN.binormal, IN.oNSp, diffuse, num_samplesF); //IMPLICIT CAST //Estimate the single scattering at point M: float3 coeffsPixel = float3(currentLayer/16.0, ((currentLayer+4.0)/16.0), ((currentLayer+8.0)/16.0)); //16 pixels in tex, divide by 16 for 0-1 tex space currentLayerCoeffs_S = tex1Dlod(matrix_tex, float4(coeffsPixel.r, 0, 0, 1)); //0-3rd pixel currentLayerCoeffs_T = tex1Dlod(matrix_tex, float4(coeffsPixel.g, 0, 0, 1)); //4-7th pixel range currentLayerCoeffs_g = tex1Dlod(matrix_tex, float4(coeffsPixel.b, 0, 0, 1)); //8-11th pixel range -- only r component of this texel used mScattering = currentLayerCoeffs_S * float4(reducedIntensity, 1.0) * PhaseFunction(currentLayerCoeffs_g.x, theta); //L_ri(M, omega_out) //Attenuate the scattered radiance along PM and add the contribution of point M p_omega_out += float3(mScattering * AttenuationPM * -PMstep); //Move to the next sample M and compute its tex coords and attenuation umvm.x += texCoordStep.x; umvm.y += texCoordStep.y; depthM += depthStep; m += PMstep; AttenuationPM *= exp(-currentLayerCoeffs_T*length(PMstep));}return color_mapping(IN, p_omega_out, ambient, diffuse, specular, specularPower, cm, sstm, nm);}////////////////////////////////////////// TECHNIQUES ///////////////////////////////////////////////////////////////technique SSTM <string Script = "Pass=p0;";> { pass p0 <string Script = "Draw=geometry;"; > { VertexShader = compile vs_3_0 view_spaceVS(gWorldXf, gWvpXf); ZEnable = true; ZWriteEnable = true; ZFunc = LessEqual; AlphaBlendEnable = false; CullMode = None; PixelShader = compile ps_3_0 pixel_shader( specularPower, ambient, diffuse, specular, cm, sstm, matrix_tex, nm); }}[/source]

The file is attached here as well because it's not really displaying properly here.