source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/globillum.cg @ 3104

////////////////////
// SSAO + color bleeding shader
// based on shader of Alexander Kusternig

#include "../shaderenv.h"


struct fragment
{
        float2 texCoord: TEXCOORD0; 
        float3 view: TEXCOORD1;
};


struct pixel2
{
        float4 ssao_col: COLOR0;
        float4 illum_col: COLOR1;
};


struct pixel
{
        float4 illum_col: COLOR0;
};


float2 myreflect(float2 pt, float2 n)
{
        // distance to plane
        float d = dot(n, pt);
        // reflect around plane
        float2 rpt = pt - d * 2.0f * n;
        return rpt;
}

struct GiStruct
{
        float3 illum;
        float2 ao;
};



inline float3 Interpol(float2 w, float3 bl, float3 br, float3 tl, float3 tr)
{
        float3 x1 = lerp(bl, tl, w.y);
        float3 x2 = lerp(br, tr, w.y); 
        float3 v = lerp(x1, x2, w.x); 

        return v;
}


/** Computes  diffuse reflections + ambient occlusion
*/
GiStruct globIllum(fragment IN,
                                   uniform sampler2D colors,
                                   uniform sampler2D noiseTexture,
                                   uniform float2 samples[NUM_SAMPLES],
                                   uniform float3 currentNormal,
                                   uniform float3 centerPosition,
                                   float scaleFactor,
                                   uniform float3 bl,
                                   uniform float3 br,
                                   uniform float3 tl,
                                   uniform float3 tr
                                   , uniform float3 viewDir
                                   )
{
        GiStruct gi;

        // Check in a circular area around the current position.
        // Shoot vectors to the positions there, and check the angle to these positions.
        // Summing up these angles gives an estimation of the occlusion at the current position.

        // ao is in stored in the w component
        float3 total_color = float3(0, 0, 0);
        float total_ao = 0.0f;
        float numSamples = 0.0f;

        ////////////
        //-- the main sampling loop

        for (int i = 0; i < NUM_SAMPLES; i ++) 
        {
                const float2 offset = samples[i];

#if 1
                ////////////////////
                // add random noiseTex: reflect around random normal vector (warning: slow!)
                float2 mynoise = tex2D(noiseTexture, IN.texCoord.xy).xy;
                float2 offsetTransformed = myreflect(offset, mynoise);
#else
                float2 offsetTransformed = offset;
#endif
                // weight with projected coordinate to reach similar kernel size for near and far
                float2 texcoord = IN.texCoord.xy + offsetTransformed * scaleFactor;

                //if ((texcoord.x <= 1.0f) && (texcoord.x >= 0.0f) && (texcoord.y <= 1.0f) && (texcoord.y >= 0.0f)) ++ numSamples;


                //////////
                //-- reconstruct world space position from sample

                const float4 sample = tex2Dlod(colors, float4(texcoord, 0, 0));
                //const float4 sample = tex2D(colors, texcoord);

                const float eyeSpaceDepth = sample.w;
                float3 rotView = Interpol(texcoord, bl, br, tl, tr);
                
                const float3 samplePos = - rotView * eyeSpaceDepth;
                const float3 sampleCol = sample.xyz;

                // distance between current position and sample position controls AO intensity.

                float3 dirSample = samplePos - centerPosition.xyz;
                const float magSample = length(dirSample);
                // normalize
                dirSample /= magSample;

                // use angle between current normal and direction to sample controls AO intensity.
                float cosAngle = max(dot(dirSample, currentNormal), 0);

                const float denom = (DISTANCE_SCALE + magSample * magSample);

                float2 intensity = float2(SAMPLE_INTENSITY, ILLUM_INTENSITY);
                intensity /= denom;

                // if normal perpenticular to view dir, only the samples approx count half
#if 1
                const float viewCorrect = 1.0f + VIEW_CORRECTION_SCALE * dot(viewDir, currentNormal);
        
                total_ao += cosAngle * intensity.x * viewCorrect;
                total_color += cosAngle * intensity.y * sampleCol * viewCorrect;
#else
                total_ao += cos_angle * intensity.x;
                total_color += cos_angle * intensity.y * sampleCol;
#endif
        }

        gi.illum = total_color;
        gi.ao = float2(max(0.0f, 1.0f - total_ao), numSamples);

        return gi;
}



pixel2 main(fragment IN, 
                   uniform sampler2D colors,
                   uniform sampler2D normals,
                   uniform sampler2D noiseTex,
                   uniform float2 samples[NUM_SAMPLES],
                   uniform sampler2D oldSsaoTex,
                   uniform sampler2D oldIllumTex,
                   const uniform float4x4 oldModelViewProj,
                   const uniform float4x4 modelViewProj,
                   uniform float temporalCoherence,
                   uniform float3 bl,
                   uniform float3 br,
                   uniform float3 tl,
                   uniform float3 tr
                   )
{
        pixel2 OUT;

        float4 norm = tex2Dlod(normals, float4(IN.texCoord, 0 ,0));
        float3 normal = normalize(norm.xyz);    

        
        /////////////
        //-- reconstruct position from the eye space depth

        float3 viewDir = IN.view;
        const float eyeDepth = tex2Dlod(colors, float4(IN.texCoord, 0, 0)).w;
        
        const float4 eyeSpacePos = float4(-viewDir * eyeDepth, 1.0f);

        // calculcate the current projected depth for next frame
        float4 currentPos = mul(modelViewProj, eyeSpacePos);

        const float w = SAMPLE_RADIUS / currentPos.w;
        currentPos /= currentPos.w;
        
        const float currentDepth = currentPos.z * PRECISION_SCALE;

        ///////////
        //-- compute color bleeding + ao

        GiStruct gi = globIllum(IN, colors, noiseTex, samples, normal, eyeSpacePos, w, bl, br, tl, tr, normalize(IN.view));
        

        /////////////////
        //-- compute temporally smoothing

        // reprojection new frame into old one 
        // calculate projected depth
        float4 projPos = mul(oldModelViewProj, eyeSpacePos);
        projPos /= projPos.w;

        // the current depth projected into the old frame
        const float projDepth = projPos.z * PRECISION_SCALE;

        // fit from unit cube into 0 .. 1
        float2 tex = projPos.xy * 0.5f + 0.5f;

        // retrieve the sample from the last frame
        float3 oldSsao = tex2D(oldSsaoTex, tex).xyz;
        float3 oldIllum = tex2D(oldIllumTex, tex).xyz;

        const float oldDepth = oldSsao.z;
        //const float depthDif = 1.0f - projDepth / oldDepth;
        const float depthDif = projDepth - oldDepth;

        // the weights that indicate the state of convergence
        const float oldWeight = clamp(oldSsao.y, .0f, temporalCoherence);
        float newWeight;

        //const float oldNumSamples = oldSsao.y;
        
        if ((temporalCoherence > 1e-6f) &&
                (tex.x >= 0.0f) && (tex.x < 1.0f) && 
                (tex.y >= 0.0f) && (tex.y < 1.0f) && 
                (abs(depthDif) < MIN_DEPTH_DIFF)
                // check if something changed in the surrounding area
                //&& (oldNumSamples > 0.2 * gi.ao.y)
                )
        {
                newWeight = oldWeight + 1;

                float4 tmp = float4(gi.ao.x, gi.illum);
                float4 oldTmp = float4(oldSsao.x, oldIllum);

                float4 interpol = (tmp + oldTmp * oldWeight) / newWeight;

                OUT.ssao_col.x = interpol.x;
                OUT.illum_col.xyz = interpol.yzw;
        }
        else
        {
                newWeight = 0;

                OUT.ssao_col.x = gi.ao.x;
                OUT.illum_col.xyz = gi.illum;
        }

        OUT.ssao_col.y = newWeight;
        OUT.ssao_col.z = currentDepth;

        return OUT;
}


pixel combine(fragment IN, 
                          uniform sampler2D colorsTex,
                          uniform sampler2D ssaoTex,
                          uniform sampler2D illumTex
                          )
{
        pixel OUT;

        float4 col = tex2Dlod(colorsTex, float4(IN.texCoord, 0, 0));
        float ao = tex2Dlod(ssaoTex, float4(IN.texCoord, 0, 0)).x;

        float3 illum = tex2Dlod(illumTex, float4(IN.texCoord, 0, 0)).xyz;

        OUT.illum_col.xyz = (col.xyz + illum) * ao;
        //OUT.illum_col.xyz = col.xyz * ao;

        OUT.illum_col.w = col.w;

        return OUT;
}