unity_native_render_plugin/Assets/Scripts/Features/OIT/WBOIT/WBOITBlend.shader

Shader "Hidden/OIT/WBOITBlend"
{

    SubShader
    {
        ZTest Always Cull Back ZWrite Off Fog { Mode Off }
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            sampler2D _CameraColorTex;
            sampler2D _AccumTex;
			sampler2D _RevealageTex;

            v2f vert (uint vertexID: SV_VertexID)
            {
                v2f o;
                float2 uv = float2((vertexID << 1) & 2, vertexID & 2);
                // 如果 ZWrite Off，在 gl 下 CCW 逆时针环绕，dx 默认 CW 顺时针环绕，需要 uv.xy = uv.yx;
                float4 pos = float4(uv * 2.0 - 1.0, UNITY_NEAR_CLIP_VALUE, 1.0);
                #ifdef UNITY_PRETRANSFORM_TO_DISPLAY_ORIENTATION
                    pos = ApplyPretransformRotation(pos);
                #endif

                #if UNITY_UV_STARTS_AT_TOP
                    uv = float2((vertexID << 1) & 2, 1.0 - (vertexID & 2));
                #endif

                o.vertex = pos;
                o.uv = uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
      		    fixed4 background = tex2D(_CameraColorTex, i.uv);
				float4 accum = tex2D(_AccumTex, i.uv);
				float r = tex2D(_RevealageTex, i.uv).r;

				fixed4 col = float4(accum.rgb / clamp(accum.a, 1e-4, 5e4), r);

				return (1.0 - col.a) * col + col.a * background;
            }
            ENDCG
        }
    }
}