Blur CG OBS

// Based on libretro shader https://github.com/libretro/common-shaders/blob/master/test/lab/misc/sharpness.cg
// Converted to obs effect file by Nibbles

uniform float4x4 ViewProj;
uniform texture2d image;
uniform float4x4 color_matrix;
uniform float3 color_range_min = {0.0, 0.0, 0.0};
uniform float3 color_range_max = {1.0, 1.0, 1.0};

uniform texture2d target;
uniform float4 color = {1.0, 1.0, 1.0, 1.0};

uniform float sharpness;
uniform float texture_width;
uniform float texture_height;

sampler_state def_sampler {
    Filter   = Linear;
    AddressU = Clamp;
    AddressV = Clamp;
};

struct VertInOut {
    float4 pos : POSITION;
    float2 uv  : TEXCOORD0;
};

struct VertOut {
    float4 pos : POSITION;
    float4 col : COLOR;
    float2 uv  : TEXCOORD0;
};

VertOut VSDefault(VertInOut vert_in)
{
    VertOut vert_out;
    vert_out.pos = mul(float4(vert_in.pos.xyz, 1.0), ViewProj);
    vert_out.uv  = vert_in.uv;
    vert_out.col = color;

    return vert_out;
}

float4 PSDrawMatrix(VertOut vert_in) : TARGET
{
    float numBlurPixelsPerSide = 4.0;
    float2  blurMultiplyVec = float2(1.0, 0.0);
    float2  blurMultiplyVec2 = float2(0.0, 1.0);
    float sigma = 4.0;
    float pi = 3.14159265;
    float blurSize = sharpness / 25;

    float3 incrementalGaussian = float3(1.0 / (sqrt(2.0 * pi) * sigma), exp(-0.5 / (sigma * sigma)), exp(-0.5 / (sigma * sigma)) * exp(-0.5 / (sigma * sigma)));

    float4 avgValue = vec4(0.0, 0.0, 0.0, 0.0);
    float coefficientSum = 0.0;

    avgValue += image.Sample(def_sampler, vert_in.uv) * incrementalGaussian.x;
    coefficientSum += incrementalGaussian.x;
    incrementalGaussian.xy *= incrementalGaussian.yz;

    for (float i = 1.0f; i <= numBlurPixelsPerSide; i++)
    {
        avgValue += image.Sample(def_sampler, vert_in.uv - i * blurSize * blurMultiplyVec) * incrementalGaussian.x;
        avgValue += image.Sample(def_sampler, vert_in.uv + i * blurSize * blurMultiplyVec) * incrementalGaussian.x;
        avgValue += image.Sample(def_sampler, vert_in.uv - i * blurSize * blurMultiplyVec2) * incrementalGaussian.x;
        avgValue += image.Sample(def_sampler, vert_in.uv + i * blurSize * blurMultiplyVec2) * incrementalGaussian.x;

        coefficientSum += 4 * incrementalGaussian.x;
        incrementalGaussian.xy *= incrementalGaussian.yz;
    }

    return avgValue / coefficientSum;
}

technique Draw
{
    pass
    {
        vertex_shader = VSDefault(vert_in);
        pixel_shader  = PSDrawMatrix(vert_in);
    }
}

technique DrawMatrix
{
    pass
    {
        vertex_shader = VSDefault(vert_in);
        pixel_shader  = PSDrawMatrix(vert_in);
    }
}