ColorRepairShader.shader

Shader "Custom/ColorRepairShader"
{
	Properties
	{
		_MainTex("Texture", 2D) = "white" {}
		_Key("Key Color", color) = (0,0,0,0)
	}
		Subshader
	{
		Pass
		{
			CGPROGRAM
			#pragma vertex vertex_shader
			#pragma fragment pixel_shader
			#pragma target 3.0

			sampler2D _MainTex;
		    float4 _Key;

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

			structure vertex_shader(float4 vertex:POSITION,float2 uv : TEXCOORD0)
			{
				structure vs;
				vs.vertex = UnityObjectToClipPos(vertex);
				vs.uv = uv;
				return vs;
			}

			float4 pixel_shader(structure ps) : SV_TARGET
			{
				float4 color = tex2D(_MainTex, ps.uv);

				float a = saturate(color.a);
				float oma = 1 - a;
				float oda = a <= 0 ? 0 : 1 / a;

				return color.a <= 0
					? float4(0, 0, 0, 0)
					: float4(
						saturate((color.r - _Key.r * oma) * oda),
						saturate((color.g - _Key.g * oma) * oda),
						saturate((color.b - _Key.b * oma) * oda), a);
			}

			ENDCG

		}
	}
}