高级纹理_折射

折射

折射是光线穿过折射率不同的两种介质所产生的现象，其中入射角和出射角遵循斯涅尔定律（snell’s low）

Shader "Unlit/Refraction"
{
    Properties
    {
        _Color ("Color Tint", Color) = (1, 1, 1, 1)
        _RefractColor ("Refraction Color", Color) = (1, 1, 1, 1)
        _RefractAmount ("Refraction Amount", Range(0, 1)) = 1
        _RefractRatio ("Refraction Ratio", Range(0.1, 1)) = 0.5
        _Cubemap ("Refraction Cubemap", Cube) = "_Skybox" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" "Queue"="Geometry"}
        LOD 100

    
            
        Pass { 
            Tags { "LightMode"="ForwardBase" }
            
            CGPROGRAM
            
            #pragma multi_compile_fwdbase
            
            #pragma vertex vert
            #pragma fragment frag
            
            #include "Lighting.cginc"
            #include "AutoLight.cginc"


            fixed4 _Color;
            fixed4 _RefractColor;
            float _RefractAmount;
            fixed _RefractRatio;
            samplerCUBE _Cubemap;


            struct a2v {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
            };

            struct v2f {
                float4 pos : SV_POSITION;
                float3 worldPos : TEXCOORD0;
                fixed3 worldNormal : TEXCOORD1;
                fixed3 worldViewDir : TEXCOORD2;
                fixed3 worldRefr : TEXCOORD3;
                SHADOW_COORDS(4)
            };
            
            v2f vert(a2v v) {

                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                
                o.worldNormal = UnityObjectToWorldNormal(v.normal);
                
                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;
                
                o.worldViewDir = UnityWorldSpaceViewDir(o.worldPos);
                
                // 计算世界空间的折射率dir

                o.worldRefr = refract(-normalize(o.worldViewDir), normalize(o.worldNormal), _RefractRatio);
                
                TRANSFER_SHADOW(o);
                
                return o;
            }
            fixed4 frag(v2f i) : SV_Target {
                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));
                fixed3 worldViewDir = normalize(i.worldViewDir);
                                
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
                
                fixed3 diffuse = _LightColor0.rgb * _Color.rgb * max(0, dot(worldNormal, worldLightDir));
                
                // //使用世界空间中的折射目录来访问cubemap

                fixed3 refraction = texCUBE(_Cubemap, i.worldRefr).rgb * _RefractColor.rgb;
                
                UNITY_LIGHT_ATTENUATION(atten, i, i.worldPos);
                
                // 混合漫射颜色和折射颜色
                fixed3 color = ambient + lerp(diffuse, refraction, _RefractAmount) * atten;
                
                return fixed4(color, 1.0);
            }
            ENDCG
        }
    }
    FallBack "Reflective/VertexLit"
}