Shader "Builtin Gaussian Splat Composite"
{
    SubShader
    {
        Pass
        {
            Name "GaussianComposite"
            Tags { "LightMode" = "GaussianComposite" }
            Cull Off
            ZWrite Off
            ZTest Always
            Blend One OneMinusSrcAlpha
            HLSLPROGRAM
            #pragma target 4.5
            #pragma vertex MainVS
            #pragma fragment MainPS

            Texture2D GaussianSplatAccumulationTexture;

            struct VSOutput
            {
                float4 position : SV_POSITION;
            };

            VSOutput MainVS(uint vertexId : SV_VertexID)
            {
                const float2 positions[3] = {
                    float2(-1.0f, -1.0f),
                    float2(-1.0f,  3.0f),
                    float2( 3.0f, -1.0f)
                };

                VSOutput output;
                output.position = float4(positions[vertexId], 1.0f, 1.0f);
                return output;
            }

            float4 MainPS(VSOutput input) : SV_TARGET
            {
                const int2 pixelCoord = int2(input.position.xy);
                return GaussianSplatAccumulationTexture.Load(int3(pixelCoord, 0));
            }
            ENDHLSL
        }
    }
}