UnityShaderBook/Assets/Shaders/Extra/Reflect/ReflectShaderByGrabPass.shader

Shader "Unlit/ReflectShaderByGrabPass"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_BumpMap ("Normal Map", 2D) = "bump" {}
		_GlassColor ("Glass Color" ,COLOR) = (1,1,1,1) 
		_ScaleTest("Scale Vertex" ,Range(0,1)) = 1
		_TexTint("Tex Tint",Range(0.0,3.0)) = 0.0
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" "Queue"="Transparent" }
		LOD 100
		GrabPass { "_RefractionTex2" }
		Cull Off
		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			//#pragma multi_compile_fog
			
			#include "UnityCG.cginc"
			sampler2D _RefractionTex2;
			float4 _RefractionTex2_ST;
			sampler2D _BumpMap;
			float4 _BumpMap_ST;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			float4 _GlassColor;
			float _TexTint;
			float _ScaleTest;


			struct a2v
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 tangent : TANGENT;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex : SV_POSITION;
				float4 scrPos : TEXCOORD0;
				float2 uv : TEXCOORD1;
				half3 wNormal : TEXCOORD2;
                half3 wTangent : TEXCOORD3;
                half3 wBitangent : TEXCOORD4;
				float3 worldPos : TEXCOORD5;
				UNITY_FOG_COORDS(1)
			};

			v2f vert (a2v v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				//o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				//o.vertex = float4(o.vertex.x+(1+sin(o.vertex.x+_ScaleTest)),o.vertex.y,o.vertex.z,o.vertex.w);
				o.scrPos = ComputeGrabScreenPos(o.vertex);
				o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
                o.uv = v.uv;
                o.wTangent = UnityObjectToWorldDir(v.tangent.xyz);
                o.wNormal = UnityObjectToWorldNormal(v.normal);
                // compute bitangent from cross product of normal and tangent
                // 通过计算法线与切线的叉积，得到二次切线bitangent,叉积*切线方向
                // half tangentSign = v.tangent.w * unity_WorldTransformParams.w;
                // output the tangent space matrix
                half tangentSign = v.tangent.w;
                o.wBitangent = cross(o.wNormal, o.wTangent) * tangentSign;
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 tex = tex2D(_MainTex, i.uv);
				half3 tnormal = UnpackNormal(tex2D(_BumpMap, i.uv));
				float3x3 TBNMatrix = float3x3(i.wTangent,i.wBitangent,i.wNormal);
				half3 worldNormal = mul(tnormal,TBNMatrix);
				half3 worldViewDir = UnityWorldSpaceViewDir(i.worldPos);

				half3 worldRefra = refract(worldViewDir,worldNormal,_ScaleTest);
				
				fixed4 texTint = _TexTint*fixed4(i.vertex.z,i.vertex.z,i.vertex.z,1);
				// sample the texture
				float2 offset = worldRefra.xy;
				i.scrPos.xy = offset * i.scrPos.z + i.scrPos.xy;
				//i.scrPos.xy = tex.xy * i.scrPos.z + i.scrPos.xy;
				fixed4 refrCol = tex2D(_RefractionTex2, i.scrPos.xy/i.scrPos.w);
				fixed4 col = tex2D(_RefractionTex2, i.uv);
				
				return refrCol*_GlassColor+tex*texTint;
				//return tex*_TexTint;
			}
			ENDCG
		}
	}
}