Texture2D<float4> PositionTexture : register(t0, space2);
SamplerState Sampler0 : register(s0, space2);

Texture2D<float4> NormalTexture : register(t1, space2);
SamplerState Sampler1 : register(s1, space2);

Texture2D<float4> NoiseTexture : register(t2, space2);
SamplerState Sampler2 : register(s2, space2);

#include "randomSamplesFloat3.hlsli"

cbuffer Uniforms : register(b0, space3)
{
    float4x4 View;
    float4x4 ViewProjection;
    float4x4 Projection;
    float2 extents;
    float radius; // = 0.5;
    float bias; // = 0.025;
    int numSamples; // up to 64
};

float4 main(float2 UV: TEXCOORD0) : SV_Target0
{
    float2 uv = UV;
    uv.y *= -1;
    uv.y += 1.0;

    float2 scale = float2(1280 / 4.0, 720 / 4.0);

    float4 c = PositionTexture.Sample(Sampler0, uv);
    float3 position = mul(View, PositionTexture.Sample(Sampler0, uv)).xyz;
    if (position.z < 0.01)
    {
        return 1.0;
    }

    float3 normal = NormalTexture.Sample(Sampler1, uv).xyz;
    float3 randomVec = normalize(NoiseTexture.Sample(Sampler2, uv * scale).xyz);
    // randomVec = normalize(float3(1.0, 1.0, 0.0) + randomVec * 0.00001);
    // randomVec = mul(View, randomVec);

    float3 x = normal;

    float3 tangent = normalize(randomVec - normal * dot(randomVec, normal));
    float3 bitangent = cross(normal, tangent);
    float3x3 TBN = transpose(float3x3(tangent, bitangent, normal));

    x = tangent;

    float occlusion = 0.0;

    x = (normal + 1.0) * 0.5; // -1 -> 0 . 1.0 -> 1.0  0 ->  0.5

    // x = tangent;
    //for(int i = 0; i < numSamples; i += 1)
    for(int i = 0; i < numSamples; i += 1)
     {
        float d = length(SamplingKernel[i]);
        //float3 samplePos = mul(TBN, d * normalize(SamplingKernel[i] * float3(1.0, 1.0, 1.0))); //float3(0.0, 0.0, 1.0)); // from tangent to view-space
        float3 samplePos = mul(TBN, SamplingKernel[i] + float3(0.0, 0.0, 0.05)); //float3(0.0, 0.0, 1.0)); // from tangent to view-space
        samplePos = position + samplePos * radius; 
        
        // project sample position (to sample texture) (to get position on screen/texture)
        float4 offset = float4(samplePos, 1.0);
        // c = offset - float4(position, 1.0);

        offset = mul(Projection, offset); // from view to clip-space
        offset.xyz /= offset.w; // perspective divide
        offset.xyz = offset.xyz * 0.5 + 0.5; // transform to range 0.0 - 1.0
        
        offset.y *= -1;
        offset.y += 1.0;

        // x += (float3(offset.xy - uv, 0.0) * 0.5 + 0.5) / numSamples;
        // get sample depth
        float sampleDepth = mul(View, PositionTexture.Sample(Sampler0, offset.xy)).z; // texture(gPosition, offset.xy).z; // get depth value of kernel sample
        // x += float3(sampleDepth, sampleDepth, sampleDepth) / numSamples;
        // x -= float3(samplePos.z, samplePos.z, samplePos.z) / numSamples;
        // c = float4(sampleDepth, sampleDepth, sampleDepth, 1.0) / 100;
        // c = float4(offset) * 2.0 - 0.6 ;

        // range check & accumulate
        float rangeCheck = smoothstep(0.0, 1.0, radius / abs(position.z - sampleDepth));
        occlusion += (sampleDepth <= samplePos.z - bias ? 1.0 : 0.0) * rangeCheck;           

        if (samplePos.z > 30) 
        {
            occlusion *= max(0.0, 1.0 - ((samplePos.z - 30) / 300));
        }
    }

    occlusion = 1.0 - (occlusion / numSamples); 
    // occlusion = 1.0 - occlusion;
    // c += PositionTexture.Sample(Sampler0, uv).x * 0.00001;
    // c += NormalTexture.Sample(Sampler1, uv).x * 0.00001;
    // c += NoiseTexture.Sample(Sampler2, uv).x * 0.00001;
    // float x = length(c);
    // c = float4(x, x, x, 1.0);
    
#if 1
    c = occlusion;
#else

    c = mul(View, PositionTexture.Sample(Sampler0, uv)).z / 100; // texture(gPosition, offset.xy).z; // get depth value of kernel sample
#endif
    //float j = x.z;
    //c = float4(x, 1.0);
    
    return c + occlusion * 0.00001;
}