Unity 镜面反射

一、公式
specuColor = Kd*_LightColor0*pow(max(R·V 0), _Shininess)；
Kd–环境光颜色、顶点颜色、点光源的距离衰减
_LightColor0–光源颜色
R·V–反射光向量 · 观察向量

二、逐顶点着色（古罗着色）

Shader "Custom/MySpecular_Vertex"{    Properties    {        _MainTex ("Texture", 2D) = "white" {}        _Bright("Bright",Float) = 2        _Shininess("Shininess",Float) = 10    }    SubShader    {        Tags { "RenderType" = "Opaque" }        LOD 100        Pass        {            Tags{ "LightMode" = "ForwardBase" }            CGPROGRAM            #pragma vertex vert            #pragma fragment frag            #include "UnityCG.cginc"            #include "Lighting.cginc"            uniform float _Shininess;            uniform float _Bright;            uniform sampler2D _MainTex;            struct appdata            {                float4 vertex:POSITION;                float2 texcoord:TEXCOORD0;                half3 normal:NORMAL;            };            struct v2f            {                float4 pos:SV_POSITION;                float2 uv:TEXCOORD0;                fixed4 difColor : COLOR0;                fixed4 specuColor : COLOR1;            };            v2f vert(in appdata v)            {                v2f o;                o.pos = UnityObjectToClipPos(v.vertex);                o.uv = v.texcoord;                float3 vertexWorldPos = mul(unity_ObjectToWorld, v.vertex);                float3 N = normalize(mul((float3x3)unity_ObjectToWorld, v.normal));//法线                float3 L;//入射光方向                float atten;//点光源的距离衰减系数                if (_WorldSpaceLightPos0.w == 0)//_WorldSpaceLightPos0:平行光: (world space direction, 0)；                {                    L = normalize(_WorldSpaceLightPos0);                    atten = 1;                }                else //_WorldSpaceLightPos0: 其他光: (world space position, 1).                {                    float3 light2Vertex = _WorldSpaceLightPos0 - vertexWorldPos;                    L = normalize(light2Vertex);                    float Length = length(light2Vertex);                    atten = 1 / Length;                }                float Kd = atten*_Bright/**UNITY_LIGHTMODEL_AMBIENT*/;                //计算入射光和法线的夹角的余弦值，并剔除小于零的值（小于0的值相当于从物体的背面向物体表面照射，没有物理意义）                float cos = max(dot(N, L), 0);                fixed4 difColor = Kd*_LightColor0 *cos;//漫反射光的颜色                //镜面反射                float3 R = reflect(-L, N);                float3 V= normalize(_WorldSpaceCameraPos - vertexWorldPos);                fixed4 specuColor = Kd* _LightColor0*pow(max(dot(R, V), 0), _Shininess);                o.difColor = difColor;                o.specuColor = specuColor;                return o;            }            fixed4 frag(in v2f i) :SV_Target            {                fixed4 col;                //纹理采样                col = tex2D(_MainTex, i.uv);                col *= i.difColor;                col += i.specuColor;                return col;            }            ENDCG        }    }}

三、逐像素着色（冯式着色）

Shader "Custom/MySpecular_Fragment"{    Properties    {        _MainTex("Texture", 2D) = "white" {}        _Bright("Bright",Float) = 2        _Shininess("Shininess",Float) = 10    }    SubShader    {        Tags{ "RenderType" = "Opaque" }        LOD 100        Pass       {            Tags{ "LightMode" = "ForwardBase" }            CGPROGRAM            #pragma vertex vert            #pragma fragment frag            #include "UnityCG.cginc"            #include "Lighting.cginc"            uniform float _Shininess;            uniform float _Bright;            uniform sampler2D _MainTex;            struct appdata            {                float4 vertex:POSITION;                float2 texcoord:TEXCOORD0;                float3 normal:NORMAL;            };            struct v2f            {                float4 pos:SV_POSITION;                float2 uv:TEXCOORD0;                float3 normalDir:TEXCOORD1;                float3 worldPos:TEXCOORD2;            };            v2f vert(in appdata v)            {                v2f o;                o.pos = UnityObjectToClipPos(v.vertex);                o.uv = v.texcoord;                o.normalDir = normalize(mul((float3x3)unity_ObjectToWorld, v.normal));                o.worldPos = mul((float3x3)unity_ObjectToWorld, v.vertex);                return o;            }            fixed4 frag(in v2f i) :SV_Target            {                fixed4 col;            col = tex2D(_MainTex, i.uv);            float3 N = normalize(i.normalDir);            float3 L;            float atten;            if (_WorldSpaceLightPos0.w == 0)            {                L = normalize(_WorldSpaceLightPos0);                atten = 1;            }            else            {                float3 light2Vertex = _WorldSpaceLightPos0 - i.worldPos;                L = normalize(light2Vertex);                float Length = length(light2Vertex);                atten = 1 / Length;            }            float Kd = atten*_Bright;            float4 difColor = Kd*_LightColor0*max(0, dot(N, L));            float3 R = reflect(-L, N);            float3 V = normalize(_WorldSpaceCameraPos - i.worldPos);            float4 specuColor = Kd*_LightColor0*pow(max(dot(R,V), 0), _Shininess);            col *= difColor;            col += specuColor;            return col;            }            ENDCG        }    }       }