【Unity】ソーベルフィルターでエッジ検出【Shader】

SobelEdge.shader

Shader "Unlit/SobelEdge"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}	
		_Width("Width",float)=1920
		_Height("Height",float)=1080  	      
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag			
			
			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

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

			sampler2D _MainTex;
			float _Width;
			float _Height; 
			
			float gray(fixed4 c)
      			{
           			return 0.2126*c.r+0.7152*c.g+0.0722*c.b;
      			}
              
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{				
				float dx=1/_Width;
                		float dy=1/_Height;
                
                		float c00=gray(tex2D(_MainTex,i.uv+float2(-dx,-dy)));
                		float c01=gray(tex2D(_MainTex,i.uv+float2(0,-dy)));
				float c02=gray(tex2D(_MainTex,i.uv+float2(dx,-dy))); 	
                		float c10=gray(tex2D(_MainTex,i.uv+float2(-dx,0)));
                		float c12=gray(tex2D(_MainTex,i.uv+float2(dx,0)));
                		float c20=gray(tex2D(_MainTex,i.uv+float2(-dx,dy)));
                		float c21=gray(tex2D(_MainTex,i.uv+float2(0,dy)));
                		float c22=gray(tex2D(_MainTex,i.uv+float2(dx,dy)));
                
                		float sx=-1.0*c00+-2.0*c10+-1.0*c20+1.0*c02+2.0*c12+1.0*c22;
                		float sy=1.0*c00+2.0*c01+1.0*c02+-1.0*c20+-2.0*c21+-1.0*c22;
                
                		return sqrt(sx*sx+sy*sy); 
			}
			ENDCG
		}
	}
}