final01_SSAO.fsh

//
#version 130


uniform sampler2D sampler0;
uniform sampler2D sampler1;
uniform sampler2D sampler2;
uniform sampler2D stepSampler0;
uniform sampler2D cleanDepth;

uniform float displayWidth;
uniform float displayHeight;
uniform float aspectRatio;
uniform float near;
uniform float far;

vec4 TexCoord0 = gl_TexCoord[0];

float
getDepth (vec2 coord)
{

    if (coord.x < 0.0)
        coord.x = -coord.x;     // should not sample outside the screen as there are no infos
    if (coord.x > 1.0)
        coord.x = (1.0 - coord.x) + 1.0;    // Telling the shader to go back on the tex
    if (coord.y < 0.0)
        coord.y = -coord.y / 2.0;
    if (coord.y > 1.0)
        coord.y = (1.0 - coord.y) + 1.0;

    float depth = texture2D (cleanDepth, coord).x;

    depth = (2.0 * near) / (far + near - depth * (far - near));
    return depth;

}

#ifdef SSAO_ENABLED             // Stuff only SSAO uses

vec4
getSSAO ()
{

    float depth = getDepth (TexCoord0.xy);
    float d;

    if (texture2D (sampler2, TexCoord0.xy).x < 1.0)
    {
        return vec4 (1.0, 1.0, 1.0, 1.0);
    }

    float depthN = depth;
    float Rp = clamp (DISTANCE_DECAY_BEGINS, 0.0, far) / far;
    float Rp2 = clamp (DISTANCE_DECAY_ENDS, 0.0, far) / far;
    if (Rp > Rp2)
    {
        Rp = Rp2 * 0.99;
    }
    float depthPush = (depthN - Rp) / (Rp2 - Rp);

    float ao = 0.0;

    if (depthN * depthPush < 1.0)
    {                           // If max_distance is not reached, then go ahead

        float aoCap = 1.0;
        float aoMultiplier = 512.0;
        float depthTolerance = 0.000015;

        float displayScale = (displayWidth / 854);  // scale ratio for you guys playing in fullscreen, 854 is the native width

        float totalSize = EFFECT_SIZE * displayScale;   // size of the ssao "envelope", modified by your resolution ( higher resolution tend to "compress" the effect )
        // this is actually used to do some maths below
        // in order to calculate the offset between each iteration.


        float pw = (EFFECT_SIZE) / (SAMPLES * displayWidth * depth * 20);   // retake on the code to allow depth to have a saying and not get
        float ph = (EFFECT_SIZE) / (SAMPLES * displayHeight * depth * 20);  // the exact same envelope on a near object and a far object.


#ifdef FPS_GAIN
//    for( int i = 1; i <= (floor(SAMPLES*(1-(depthN*depthPush))+1)); i++ ){    // Temp code; waiting to be used for some FPS optimization - not working great yet
        for (int i = 1; i <= SAMPLES + 1; i++)
        {                       // retake on the original code to allow more "blur"
            // and more "depth" in the occlusion effect

            d = getDepth (vec2 (TexCoord0.x + pw, TexCoord0.y + ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x - pw, TexCoord0.y + ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x - pw, TexCoord0.y - ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x + pw, TexCoord0.y - ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            pw *= pow ((totalSize), 1.0 / SAMPLES);
            ph *= pow ((totalSize), 1.0 / SAMPLES);
            aoMultiplier *= 1 - ((i - 1) / SAMPLES);
        }
        ao /= (SAMPLES * 3.0);

#else
//    for( int i = 1; i <= (floor(SAMPLES*(1-(depthN*depthPush))+1)); i++ ){    // Temp code; waiting to be used for some FPS optimization - not working great yet
        for (int i = 1; i <= SAMPLES + 1; i++)
        {                       // retake on the original code to allow more "blur"
            // and more "depth" in the occlusion effect

            d = getDepth (vec2 (TexCoord0.x + (pw * 1.5), TexCoord0.y));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x + pw, TexCoord0.y + ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x, TexCoord0.y + (ph * 1.5)));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x - pw, TexCoord0.y + ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x - (pw * 1.5), TexCoord0.y));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x - pw, TexCoord0.y - ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x, TexCoord0.y - (ph * 1.5)));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            d = getDepth (vec2 (TexCoord0.x + pw, TexCoord0.y - ph));
            ao +=
                min (aoCap,
                     max (0.0, depth - d - depthTolerance) * aoMultiplier);

            pw *= pow ((totalSize), 1.0 / SAMPLES);
            ph *= pow ((totalSize), 1.0 / SAMPLES);
            aoMultiplier *= 1 - ((i - 1) / SAMPLES);
        }
        ao /= (SAMPLES * 5.0);

#endif

        ao = clamp (SSAO_MULT * ao, 0.0, 1.0);  // multiplicator
        ao = clamp ((1 - ao) + (depthN * depthPush), 0.0, 1.0);

    }
    else
    {                           // If max_distance is reached, then ignore the long computation, and giev moar fps
        ao = 1.0;
    }

    return vec4 (ao, ao, ao, 1.0);
}
#endif

void
main ()
{
    vec4 baseColor = texture2D (sampler0, TexCoord0.st);

#ifdef SSAO_ENABLED
    baseColor *= getSSAO ();
#endif
    gl_FragColor = baseColor;
}