Unity实现经验光照模型

漫反射：

Lambert:

公式：  //diffuse = ambient + _parm*lightcolor* max(0, Dot(N,L))

  fixed4 frag (v2f i) : SV_Target
  {
     //diffuse = ambient + _parm*lightcolor* max(0, Dot(N,L))
     fixed3 ambient = unity_AmbientSky;

     fixed3 N = normalize(i.worldNormal);

     fixed3 diffuse = _parm*_LightColor0.rgb * max(0,dot(i.worldNormal,_WorldSpaceLightPos0));
                
     fixed3 color = ambient + diffuse;
     return fixed4(color,1);
  }

HalfLambert:

公式： diffuse = ambient + K * lightcolor* （Dot(N,L)*0.5+0.5）

  fixed4 frag (v2f i) : SV_Target
  {
    //diffuse = ambient + _parm*lightcolor*Dot(N,L)*0.5 + 0.5
    fixed3 ambient = unity_AmbientSky;

    fixed3 N = normalize(i.worldNormal);
    
    fixed3 L = normalize(_WorldSpaceLightPos0);

    fixed3 diffuse = _parm*_LightColor0.rgb *(dot(i.worldNormal,L)* 0.5 + 0.5);
                
    fixed3 color = ambient + diffuse;
    return fixed4(color,1);
  }

镜面反射：

Phong：

公式：Spcular = spacularColor + K*pow(max(0,dot(R,V)),shininess)

 //Phong
 //specular = specularcolor + k * pow(max(0,dot(R,v)),shininess)
 fixed3 V = normalize(_worldSpaceCameraPos - i.worldPos);

 fixed3 R = reflect(-L,N);

 fixed4 specular = fixed4(1) + 1 * pow(max(0,dot(R,V)),shininess);

Blin-Phong：

公式：Spcular = spacularColor + K*pow(max(0,dot(N,H)),shininess)

 //Blin-phong
 //specular = specularcolor + k * pow(max(0,dot(N,H)),shininess)
 float3 H = normalize(L + V);
 fixed3 BlinSpecular = fixed4(1) + 1 * pow(max(0,dot(N,V)),shininess);

物体的颜色= diffuse + spcular;