#include "CoreRP/ShaderLibrary/Common.hlsl"

static const float2 poissonDisk64[64] =
{
    float2 ( 0.1187053,   0.7951565),
    float2 ( 0.1173675,   0.6087878),
    float2 (-0.09958518,  0.7248842),
    float2 ( 0.4259812,   0.6152718),
    float2 ( 0.3723574,   0.8892787),
    float2 (-0.02289676,  0.9972908),
    float2 (-0.08234791,  0.5048386),
    float2 ( 0.1821235,   0.9673787),
    float2 (-0.2137264,   0.9011746),
    float2 ( 0.3115066,   0.4205415),
    float2 ( 0.1216329,   0.383266),
    float2 ( 0.5948939,   0.7594361),
    float2 ( 0.7576465,   0.5336417),
    float2 (-0.521125,    0.7599803),
    float2 (-0.2923127,   0.6545699),
    float2 ( 0.6782473,   0.22385),
    float2 (-0.3077152,   0.4697627),
    float2 ( 0.4484913,   0.2619455),
    float2 (-0.5308799,   0.4998215),
    float2 (-0.7379634,   0.5304936),
    float2 ( 0.02613133,  0.1764302),
    float2 (-0.1461073,   0.3047384),
    float2 (-0.8451027,   0.3249073),
    float2 (-0.4507707,   0.2101997),
    float2 (-0.6137282,   0.3283674),
    float2 (-0.2385868,   0.08716244),
    float2 ( 0.3386548,   0.01528411),
    float2 (-0.04230833, -0.1494652),
    float2 ( 0.167115,   -0.1098648),
    float2 (-0.525606,    0.01572019),
    float2 (-0.7966855,   0.1318727),
    float2 ( 0.5704287,   0.4778273),
    float2 (-0.9516637,   0.002725032),
    float2 (-0.7068223,  -0.1572321),
    float2 ( 0.2173306,  -0.3494083),
    float2 ( 0.06100426, -0.4492816),
    float2 ( 0.2333982,   0.2247189),
    float2 ( 0.07270987, -0.6396734),
    float2 ( 0.4670808,  -0.2324669),
    float2 ( 0.3729528,  -0.512625),
    float2 ( 0.5675077,  -0.4054544),
    float2 (-0.3691984,  -0.128435),
    float2 ( 0.8752473,   0.2256988),
    float2 (-0.2680127,  -0.4684393),
    float2 (-0.1177551,  -0.7205751),
    float2 (-0.1270121,  -0.3105424),
    float2 ( 0.5595394,  -0.06309237),
    float2 (-0.9299136,  -0.1870008),
    float2 ( 0.974674,    0.03677348),
    float2 ( 0.7726735,  -0.06944724),
    float2 (-0.4995361,  -0.3663749),
    float2 ( 0.6474168,  -0.2315787),
    float2 ( 0.1911449,  -0.8858921),
    float2 ( 0.3671001,  -0.7970535),
    float2 (-0.6970353,  -0.4449432),
    float2 (-0.417599,   -0.7189326),
    float2 (-0.5584748,  -0.6026504),
    float2 (-0.02624448, -0.9141423),
    float2 ( 0.565636,   -0.6585149),
    float2 (-0.874976,   -0.3997879),
    float2 ( 0.9177843,  -0.2110524),
    float2 ( 0.8156927,  -0.3969557),
    float2 (-0.2833054,  -0.8395444),
    float2 ( 0.799141,   -0.5886372)
};

real PenumbraSize(real Reciever, real Blocker)
{
    return abs((Reciever - Blocker) / Blocker);
}

bool BlockerSearch(inout real averageBlockerDepth, inout real numBlockers, real lightArea, real3 coord, real2 sampleJitter, real2 sampleBias, ShadowContext shadowContext, float slice, uint texIdx, uint sampIdx, int sampleCount)
{
    real blockerSum = 0.0;
    for (int i = 0; i < sampleCount; ++i)
    {
        real2 offset = real2(poissonDisk64[i].x *  sampleJitter.y + poissonDisk64[i].y * sampleJitter.x,
                             poissonDisk64[i].x * -sampleJitter.x + poissonDisk64[i].y * sampleJitter.y) * lightArea;

        real shadowMapDepth = SampleShadow_T2DA(shadowContext, texIdx, sampIdx, coord.xy + offset, slice).x;

        if (COMPARE_DEVICE_DEPTH_CLOSER(shadowMapDepth, coord.z + dot(sampleBias, offset)))
        {
            blockerSum  += shadowMapDepth;
            numBlockers += 1.0;
        }
    }
    averageBlockerDepth = blockerSum / numBlockers;

    return numBlockers >= 1;
}

bool BlockerSearch(inout real averageBlockerDepth, inout real numBlockers, real lightArea, real3 coord, float slice, real2 sampleJitter, real2 sampleBias, Texture2DArray shadowMap, SamplerState PointSampler, int sampleCount)
{
    real blockerSum = 0.0;
    for (int i = 0; i < sampleCount; ++i)
    {
        real2 offset = real2(poissonDisk64[i].x *  sampleJitter.y + poissonDisk64[i].y * sampleJitter.x,
                             poissonDisk64[i].x * -sampleJitter.x + poissonDisk64[i].y * sampleJitter.y) * lightArea;

        real shadowMapDepth = SAMPLE_TEXTURE2D_ARRAY_LOD(shadowMap, PointSampler, coord.xy + offset, slice, 0.0).x;

        if (COMPARE_DEVICE_DEPTH_CLOSER(shadowMapDepth, coord.z + dot(sampleBias, offset)))
        {
            blockerSum  += shadowMapDepth;
            numBlockers += 1.0;
        }
    }
    averageBlockerDepth = blockerSum / numBlockers;

    return numBlockers >= 1;
}

real PCSS(real3 coord, real filterRadius, real4 scaleOffset, float slice, real2 sampleBias, real2 sampleJitter, ShadowContext shadowContext, uint texIdx, uint sampIdx, int sampleCount)
{
    real UMin = scaleOffset.z;
    real UMax = scaleOffset.z + scaleOffset.x;

    real VMin = scaleOffset.w;
    real VMax = scaleOffset.w + scaleOffset.y;

    real sum = 0.0;
    for(int i = 0; i < sampleCount; ++i)
    {
        real2 offset = real2(poissonDisk64[i].x *  sampleJitter.y + poissonDisk64[i].y * sampleJitter.x,
                             poissonDisk64[i].x * -sampleJitter.x + poissonDisk64[i].y * sampleJitter.y) * filterRadius;

        real U = coord.x + offset.x;
        real V = coord.y + offset.y;

        //NOTE: We must clamp the sampling within the bounds of the shadow atlas.
        //        Overfiltering will leak results from other shadow lights.
        //TODO: Investigate moving this to blocker search.
        if (U <= UMin || U >= UMax || V <= VMin || V >= VMax)
            sum += SampleCompShadow_T2DA(shadowContext, texIdx, sampIdx, real3(coord.xy, coord.z), slice).r;
        else
            sum += SampleCompShadow_T2DA(shadowContext, texIdx, sampIdx, real3(U, V, coord.z + dot(sampleBias, offset)), slice).r;
    }

    return sum / sampleCount;
}

real PCSS(real3 coord, real filterRadius, real4 scaleOffset, float slice, real2 sampleBias, real2 sampleJitter, Texture2DArray shadowMap, SamplerComparisonState compSampler, int sampleCount)
{
    real UMin = scaleOffset.z;
    real UMax = scaleOffset.z + scaleOffset.x;

    real VMin = scaleOffset.w;
    real VMax = scaleOffset.w + scaleOffset.y;

    real sum = 0.0;
    for(int i = 0; i < sampleCount; ++i)
    {
        real2 offset = real2(poissonDisk64[i].x *  sampleJitter.y + poissonDisk64[i].y * sampleJitter.x,
                             poissonDisk64[i].x * -sampleJitter.x + poissonDisk64[i].y * sampleJitter.y) * filterRadius;

        real U = coord.x + offset.x;
        real V = coord.y + offset.y;

        //NOTE: We must clamp the sampling within the bounds of the shadow atlas.
        //        Overfiltering will leak results from other shadow lights.
        //TODO: Investigate moving this to blocker search.
        if (U <= UMin || U >= UMax || V <= VMin || V >= VMax)
            sum += SAMPLE_TEXTURE2D_ARRAY_SHADOW(shadowMap, compSampler, real3(coord.xy, coord.z), slice).r;
        else
            sum += SAMPLE_TEXTURE2D_ARRAY_SHADOW(shadowMap, compSampler, real3(U, V, coord.z + dot(sampleBias, offset)), slice).r;
    }

    return sum / sampleCount;
}