Realization of reflection and refraction effect in unity shader cube texture

Reflection ：

If you don't consider the reflection effect , The effect of the mirror surface in the scene should be to sample the cube texture with the normal of the surface to get the color of the point .
So when we calculate the reflection , Just find the reflection direction , Then sample the cube texture in the direction of reflection .
effect ：

Code ：

Shader "Custom/Chapter10-Reflaction"
{
    
   Properties
    {
    
    _Color("Color Tint",Color)=(1,1,1,1)
    // Reflection color 
    _RefractColor("Reflection Color",Color)=(1,1,1,1)
    // Degree of reflection 
    _RefractAmount("Reflect Amount",Range(0,1))=1
    // Proportion of media 
    _RefractRatio("Refraction Ratio",Range(0.1,1))=0.5
    // Cubic texture 
    _Cubemap("Reflection Cubemap",Cube)="_Skybox"{
    }
    }
    SubShader
    {
    
    Tags {
     "RenderType"="Opaque" "Queue"="Geometry"}

    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;
    // Direction of reflected light 
    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);
    // Direction of reflection 
    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));
                fixed3 Refraction=texCUBE(_Cubemap,i.worldRefr).rgb*_RefractColor.rgb;
                UNITY_LIGHT_ATTENUATION(atten,i,i.worldPos);
                fixed3 color=ambient +lerp(diffuse,Refraction,_RefractAmount)*atten;

                return fixed4(color,1.0);
    }
    ENDCG
    }
    }
    FallBack "Reflective/VertexLit"
}

refraction

Empathy , Find the direction of refraction , Sample the cube texture .
Realization effect ：

Code ：

Shader "Custom/Chapter10-Reflaction"
{
    
   Properties
    {
    
    _Color("Color Tint",Color)=(1,1,1,1)
    // Refraction color 
    _RefractColor("Reflection Color",Color)=(1,1,1,1)
    // Degree of refraction 
    _RefractAmount("Reflect Amount",Range(0,1))=1
    // Proportion of media 
    _RefractRatio("Refraction Ratio",Range(0.1,1))=0.5
    // Cubic texture 
    _Cubemap("Reflection Cubemap",Cube)="_Skybox"{
    }
    }
    SubShader
    {
    
    Tags {
     "RenderType"="Opaque" "Queue"="Geometry"}

    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;
    // Refract the direction of light 
    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);
    // The direction of refraction 
    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));
                fixed3 Refraction=texCUBE(_Cubemap,i.worldRefr).rgb*_RefractColor.rgb;
                UNITY_LIGHT_ATTENUATION(atten,i,i.worldPos);
                fixed3 color=ambient +lerp(diffuse,Refraction,_RefractAmount)*atten;

                return fixed4(color,1.0);
    }
    ENDCG
    }
    }
    FallBack "Reflective/VertexLit"
}

Fresnel reflex

The degree of reflection is controlled by Fresnel reflection according to the direction of viewing angle . For example, in real life , We looked at the water near the lake , You can see stones, fish and so on under the water , But when we walk far away and look at the water beside the lake, we can only see the water , And I can't see the underwater scene , This is the Fresnel effect .
Fresnel approximate equation ：

• Schlick Fresnel approximate equation ： f Is the reflection coefficient , Control the intensity of Fresnel reflection

• Empricial Fresnel approximate equation ：
  effect ：
  

Code ：

Shader "Custom/Chapter10-Fresnel"
{
    
    Properties
    {
    
    _Color("Color Tint",Color)=(1,1,1,1)
    //F0
    _FresnelScale("Fresnel Scale",Range(0,1))=0.5
    // Cubic texture 
    _Cubemap("Reflection Cubemap",Cube)="_Skybox"{
    }
    }
    SubShader
    {
    
    Tags {
     "RenderType"="Opaque" "Queue"="Geometry"}

    Pass{
    
    Tags{
    "LightMode"="ForwardBase"}

    CGPROGRAM

    #pragma multi_compile_fwdbase

    #pragma vertex vert
    #pragma fragment frag

    #include "Lighting.cginc"
    #include "AutoLight.cginc"

    fixed4 _Color;
    float _FresnelScale;
    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;
    // Direction of reflected light 
    fixed3 worldRefl: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);
    // Direction of reflection 
    o.worldRefl = reflect(-o.worldViewDir,o.worldNormal);
    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));
                // The Fresnel approximation is obtained by calculation 
                fixed3 Reflection =texCUBE(_Cubemap,i.worldRefl).rgb;
                fixed fresnel =_FresnelScale+(1-_FresnelScale)*pow(1-dot(worldViewDir,worldNormal),5);
                UNITY_LIGHT_ATTENUATION(atten,i,i.worldPos);
                // Use Fresnel approximation to difference reflection color and diffuse reflection color 
                fixed3 color =ambient +lerp(diffuse,Reflection,saturate(fresnel))*atten;

                return fixed4(color,1.0);
    }
    ENDCG
    }
    }
    FallBack "Reflective/VertexLit"
}