Unity3D shader（9）——vertex shader（phong光照和BlinnPhong光照）

首先来看一下反射原理：首先通过L和N来求出R的向量，然后求出视角的向量V，最后将V和R点乘，可以求出光照强度。

承接上一篇，具体代码如下：

Shader "Custom/Vf Shader" {properties{_SpecularColor("SpecularColor",color)=(1,1,1,1)_Shininess("Shininess",range(1,8))=4}SubShader {PASS{tags{"LightMode"="ForwardBase"}CGPROGRAM#pragma vertex vert          #pragma fragment frag        #include "UnityCG.cginc"        #include "Lighting.cginc"        float _Shininess;        float4 _SpecularColor;        struct v2f{        float4 pos:POSITION;        float4 col:COLOR;        };          v2f vert(appdata_base v){        v2f o;        o.pos=UnityObjectToClipPos(v.vertex);        float3 N=normalize(v.normal);        float3 L=normalize(_WorldSpaceLightPos0);        //float3 L2=mul(_World2Object,float4(L,0)).xyz;        //float ndotl=saturate(dot(N,L2));        N=mul(float4(N,0),_World2Object);        N=normalize(N);        float ndotl=saturate(dot(N,L));        float3 I=-WorldSpaceLightDir(v.vertex);        float3 R=reflect(I,N);        float3 V=WorldSpaceViewDir(v.vertex);        R=normalize(R);        V=normalize(V);        float specularScale=pow(saturate(dot(R,V)),_Shininess);        float3 wpos=mul(_Object2World,v.vertex);        o.col=_LightColor0*ndotl*specularScale*_SpecularColor;        o.col.rgb+=Shade4PointLights(unity_4LightPosX0,unity_4LightPosY0,unity_4LightPosZ0,                                      unity_LightColor[0].rgb,unity_LightColor[1].rgb,unity_LightColor[2].rgb,unity_LightColor[3].rgb,                                      unity_4LightAtten0,                                      wpos,N                                      ) ;              return o;        }        float4 frag(v2f IN):COLOR{        return IN.col+UNITY_LIGHTMODEL_AMBIENT;        }ENDCG}}FallBack "Diffuse"}

最后的效果如图：

接着来看一下BlinnPhong的原理，通过L和V得到H向量，然后将H向量和N向量点乘得到光照强度。BlinnPhong的计算速度更快，因为它少了反射向量的计算。

Shader "Custom/Vf Shader" {properties{_SpecularColor("SpecularColor",color)=(1,1,1,1)_Shininess("Shininess",range(1,8))=4}SubShader {PASS{tags{"LightMode"="ForwardBase"}CGPROGRAM#pragma vertex vert          #pragma fragment frag        #include "UnityCG.cginc"        #include "Lighting.cginc"        float _Shininess;        float4 _SpecularColor;        struct v2f{        float4 pos:POSITION;        float4 col:COLOR;        };          v2f vert(appdata_base v){        v2f o;        o.pos=UnityObjectToClipPos(v.vertex);        float3 N=normalize(v.normal);        float3 L=normalize(_WorldSpaceLightPos0);        //float3 L2=mul(_World2Object,float4(L,0)).xyz;        //float ndotl=saturate(dot(N,L2));        N=mul(float4(N,0),_World2Object);        N=normalize(N);        float ndotl=saturate(dot(N,L));        float3 I=normalize(-WorldSpaceLightDir(v.vertex));        float3 V=normalize(WorldSpaceViewDir(v.vertex));        float3 H=I+V;        float specularScale=pow(saturate(dot(H,N)),_Shininess);        float3 wpos=mul(_Object2World,v.vertex);        o.col=_LightColor0*ndotl*specularScale*_SpecularColor;        o.col.rgb+=Shade4PointLights(unity_4LightPosX0,unity_4LightPosY0,unity_4LightPosZ0,                                      unity_LightColor[0].rgb,unity_LightColor[1].rgb,unity_LightColor[2].rgb,unity_LightColor[3].rgb,                                      unity_4LightAtten0,                                      wpos,N                                      ) ;              return o;        }        float4 frag(v2f IN):COLOR{        return IN.col+UNITY_LIGHTMODEL_AMBIENT;        }ENDCG}}FallBack "Diffuse"}