Matcap

Shader "Custom/Matcap"
{
    Properties
    {
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _Matcap ("Matcap", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }

        CGPROGRAM
        
        #pragma surface surf _NoLight noambient

        sampler2D _MainTex;
        sampler2D _Matcap;

        struct Input
        {
            float2 uv_MainTex;
            float3 worldNormal;
        };

        void surf (Input IN, inout SurfaceOutput o)
        {
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex);
                                    //UNITY_MATRIX_V : view 좌표계 메트릭스 
            float3 viewNormal = mul((float3x3)UNITY_MATRIX_V, IN.worldNormal.rgb);  //메트릭스 곱셈 
            //o.Emission = IN.worldNormal;      //색이 변함 
            //o.Emission = viewNormal;    //왼쪽이 항상 파랑 

            //o.Emission = viewNormal.x;

            //viewNormal의 x, y를 u, v로 사용가능 
            float2 matcapUV = viewNormal.xy * 0.5 + 0.5;    //normal uv 0 ~ 1 을 -1 ~ 1로 만듬 

            //o.Emission = float3(matcapUV, 0);
            o.Emission = tex2D(_Matcap, matcapUV) * c.rgb;

            o.Alpha = c.a;
        }

        float4 Lighting_NoLight(SurfaceOutput s, float3 lightDir, float atten){
            return float4(0, 0, 0, s.Alpha);
        }
        ENDCG
    }
    FallBack "Diffuse"
}