﻿Shader "SnapshotProHDRP/SobelOutline"
{
    HLSLINCLUDE

    #pragma target 4.5
    #pragma only_renderers d3d11 ps4 xboxone vulkan metal switch

    #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Common.hlsl"
    #include "Packages/com.unity.render-pipelines.core/ShaderLibrary/Color.hlsl"
    #include "Packages/com.unity.render-pipelines.high-definition/Runtime/ShaderLibrary/ShaderVariables.hlsl"
    #include "Packages/com.unity.render-pipelines.high-definition/Runtime/PostProcessing/Shaders/FXAA.hlsl"
    #include "Packages/com.unity.render-pipelines.high-definition/Runtime/PostProcessing/Shaders/RTUpscale.hlsl"

    struct Attributes
    {
        uint vertexID : SV_VertexID;
        UNITY_VERTEX_INPUT_INSTANCE_ID
    };

    struct Varyings
    {
        float4 positionCS : SV_POSITION;
        float2 texcoord   : TEXCOORD0;
        UNITY_VERTEX_OUTPUT_STEREO
    };

    Varyings Vert(Attributes input)
    {
        Varyings output;
        UNITY_SETUP_INSTANCE_ID(input);
        UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(output);
        output.positionCS = GetFullScreenTriangleVertexPosition(input.vertexID);
        output.texcoord = GetFullScreenTriangleTexCoord(input.vertexID);
        return output;
    }

    // List of properties to control your post process effect
	TEXTURE2D_X(_InputTexture);

	float3 sobel(float2 uv)
	{
		float3 x = 0.0f;
		float3 y = 0.0f;

		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2(-1, -1)).xyz * -1.0f;
		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2(-1,  0)).xyz * -2.0f;
		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2(-1,  1)).xyz * -1.0f;

		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 1, -1)).xyz *  1.0f;
		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 1,  0)).xyz *  2.0f;
		x += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 1,  1)).xyz *  1.0f;

		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2(-1, -1)).xyz * -1.0f;
		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 0, -1)).xyz * -2.0f;
		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 1, -1)).xyz * -1.0f;

		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2(-1,  1)).xyz *  1.0f;
		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 0,  1)).xyz *  2.0f;
		y += LOAD_TEXTURE2D_X(_InputTexture, uv + float2( 1,  1)).xyz *  1.0f;

		float xLum = Luminance(x);
		float yLum = Luminance(y);

		return sqrt(xLum * xLum + yLum * yLum);
	}

    float4 CustomPostProcess(Varyings input) : SV_Target
    {
        UNITY_SETUP_STEREO_EYE_INDEX_POST_VERTEX(input);

        uint2 positionSS = input.texcoord * _ScreenSize.xy;

		return float4(sobel(positionSS), 1.0f);
    }

    ENDHLSL

    SubShader
    {
        Pass
        {
            Name "SobelOutline"

            ZWrite Off
            ZTest Always
            Blend Off
            Cull Off

            HLSLPROGRAM
                #pragma fragment CustomPostProcess
                #pragma vertex Vert
            ENDHLSL
        }
    }
    Fallback Off
}
