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BrushTest.shader

Shader "Custom/BrushTest" {
	Properties {
		_MainTex ("Base (RGB)", 2D) = "white" {}
		_ShapeTex ("brush tex", 2D) = "white" {}
		_Draw ("draw prop(s,y,size,alpha)",Vector) = (0,0,0,0)
	}
	SubShader {
		Tags { "RenderType"="Opaque" }
		LOD 200
		
		CGPROGRAM
		#pragma surface surf Lambert

		sampler2D _MainTex,_ShapeTex;
		float4 _Draw;
		half4 _MainTex_TexelSize;

		struct Input {
			float2 uv_MainTex;
		};

		void surf (Input IN, inout SurfaceOutput o) {
			half2
				pos = _Draw.xy,
				size = _MainTex_TexelSize.xy * _Draw.z;
			float2
				uv = IN.uv_MainTex,
				uv2 = (uv - (pos - size * 0.5))/size;
			half intencity = _Draw.a;
			
			half4
				base = tex2D(_MainTex, uv),
				draw = tex2D(_ShapeTex, uv2);
			draw.a *= intencity;
			
			o.Emission = lerp(base, draw, draw.a);
		}
		ENDCG
	} 
	FallBack "Diffuse"
}