source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/combineSsao.cg @ 3232

#include "../shaderenv.h"
#include "common.h"


/*************************************************/
/*     Filter for combining ssao with image      */
/*************************************************/


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


struct pixel
{
        float4 illum_col: COLOR0;
};


/** Filter taking into account depth, normal discontinuities 
   and ssao convergence of a sample (the higher the more reliably
   has the sample a correct ssao value)
*/
float DiscontinuityFilter(float2 texCoord,
                                                  float4 ao,
                                                  float4 color,
                                                  uniform sampler2D ssaoTex,
                                                  uniform sampler2D normalsTex,
                                                  uniform sampler2D colorsTex,
                                                  uniform float2 filterOffs[NUM_SSAO_FILTER_SAMPLES],
                                                  float scale,
                                                  float3 bl,
                                                  float3 br,
                                                  float3 tl,
                                                  float3 tr)
{
        float average = .0f;
        float total_w = .0f;

        //const float3 centerPos = ReconstructSamplePos(ssaoTex, texCoord, bl, br, tl, tr);
        const float3 centerPos = ReconstructSamplePos(colorsTex, texCoord, bl, br, tl, tr);
        const float3 centerNormal = tex2Dlod(normalsTex, float4(texCoord, 0, 0)).xyz;

        float4 aoSample;
        float3 sampleNorm;
        float3 samplePos;
        float w;
        float4 sampleTexCoord;
        float spatialFactor;
        float normalFactor;
        float convergenceFactor;
        float len;

        const float convergenceThresh = 200.0f;

        for (int i = 0; i < NUM_SSAO_FILTER_SAMPLES; ++ i)
        {
                sampleTexCoord = float4(texCoord + filterOffs[i] * scale, .0f, .0f);

                aoSample = tex2Dlod(ssaoTex, sampleTexCoord);
                
                // check spatial discontinuity
                // note: using the depth from the color texture is not 100% correct as depth was
                // not scaled with the interpolated view vector depth yet ...
                samplePos = ReconstructSamplePos(colorsTex, sampleTexCoord.xy, bl, br, tl, tr);
                //samplePos = ReconstructSamplePos(ssaoTex, sampleTexCoord.xy, bl, br, tl, tr);

                len = min(SqrLen(centerPos - samplePos), 1e2f);
                spatialFactor = 1.0f / max(len, 1e-3f);

                convergenceFactor = aoSample.y + 1.0f;

                //sampleNorm = tex2Dlod(normalsTex, sampleTexCoord).xyz;
                //normalFactor = max(step(.2f, dot(sampleNorm, centerNormal)), 1e-2f);

                // combine the weights
                w = convergenceFactor * convergenceFactor * spatialFactor;// * normalFactor;
                
                average += aoSample.x * w;
                total_w += w;
        }

        average /= max(total_w, 1e-6f);

        return saturate(average);
}


/** Function combining image and indirect illumination buffer using a 
        depth and normal aware discontinuity filter. We assume that 
        we are using half resolution ssao for this version of the combineSsao
*/
pixel CombineSsaoHalfRes(fragment IN, 
                                                 uniform sampler2D colorsTex,
                                                 uniform sampler2D ssaoTex,
                                                 uniform sampler2D normalsTex,
                                                 uniform float2 filterOffs[NUM_SSAO_FILTER_SAMPLES],
                                                 uniform float filterWeights[NUM_SSAO_FILTER_SAMPLES],
                                                 uniform float ssaoFilterRadius,
                                                 uniform float4x4 modelViewProj,
                                                 uniform float3 bl,
                                                 uniform float3 br,
                                                 uniform float3 tl,
                                                 uniform float3 tr,
                                                 uniform float w,
                                                 uniform float h
                                                 )
{
        pixel OUT;

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

#if 0 // use half size

        // the following has to be done for half resolution ssao:
        // get the minimum convergence by exactly sampling the 4 surrounding
        // texels in the old texture, otherwise flickering because convergence
        // will be interpolated when upsampling and filter size does not match!

        float4 texelCenterConv;
        const float xoffs = .5f / w; const float yoffs = .5f / h;

        // get position exactly between old texel centers
        float2 center;
        center.x = (floor(IN.texCoord.x * w - .5f) + 1.0f) / w;
        center.y = (floor(IN.texCoord.y * h - .5f) + 1.0f) / h;

        texelCenterConv.x = tex2Dlod(ssaoTex, float4(center + float2( xoffs,  yoffs), 0, 0)).y;
        texelCenterConv.y = tex2Dlod(ssaoTex, float4(center + float2( xoffs, -yoffs), 0, 0)).y;
        texelCenterConv.z = tex2Dlod(ssaoTex, float4(center + float2(-xoffs, -yoffs), 0, 0)).y;
        texelCenterConv.w = tex2Dlod(ssaoTex, float4(center + float2(-xoffs,  yoffs), 0, 0)).y;

        const float m1 = min(texelCenterConv.x, texelCenterConv.y);
        const float m2 = min(texelCenterConv.z, texelCenterConv.w);

        const float minConvergence = min(m1, m2);
        const float convergence = minConvergence;

#else
        
        // just take unfiltered convergence in current pixel
        const float convergence = ao.y;

#endif
        
        // filter reaches size 1 pixel when sample size reaches threshold 
        // afterwards we do not use the filter anymore

        // filter up to a certain convergance value and leave out background (sky) by checking depth
        if ((convergence < SSAO_CONVERGENCE_THRESHOLD) && (col.w < 1e10f))
        {
                const float distanceScale = 1.0f;

                // descend to zero filter size after reaching thres pixels
                const float convergenceWeight = SSAO_CONVERGENCE_THRESHOLD / (ssaoFilterRadius - 1.0f);
                const float convergenceScale = convergenceWeight / (convergence + convergenceWeight);
                const float scale = ssaoFilterRadius * convergenceScale * distanceScale;

                // the filtered ssao value
                ao.x = DiscontinuityFilter(IN.texCoord, ao, col, ssaoTex, normalsTex, colorsTex, filterOffs, scale, bl, br, tl, tr);
        }

        // just apply ssao if we are not in the sky
        if (col.w < 1e10f)
                OUT.illum_col.xyz = col.xyz * max(2e-2f, 1.0f - ao.x);
                //OUT.illum_col.xyz = col.xyz * ao.x;
        else
                OUT.illum_col.xyz = col.xyz;


        //OUT.illum_col.xyz = float3(abs(ao.y * 1e2f), abs(ao.z * 1e2f), abs(ao.w * 1e2f));

        //if (convergence < (1.0f + NUM_SAMPLES * 10))
        //      OUT.illum_col.xyz = float3(1 - convergence / (NUM_SAMPLES * 10), convergence / (NUM_SAMPLES * 10), 0);
        
        //OUT.illum_col.xyz = float3(ao.z * 1e4f, ao.z * 1e4f, ao.z * 1e4f);

        //OUT.illum_col.xyz = float3(ao.x, ao.x, step(thres, convergence));
        //OUT.illum_col.xyz = float3(abs(center.x - IN.texCoord.x) * 16.0f, abs(center.y - IN.texCoord.y) * 12.0f, 0);
        //OUT.illum_col.xyz = float3(0, 1.0f - step(0.5f + NUM_SAMPLES, convergence), 1);

        OUT.illum_col.w = col.w;

        return OUT;
}