Shader-漫反射（像素实现）半兰伯特计算

• 半兰伯特光照模型
• Diffuse = 直射光颜色 *（ cosθ *0.5 +0.5）
• 兰伯特光照模型(漫反射)
• Diffuse = 直射光颜色 * max(0,cos夹角(光和法线的夹角) )  cosθ = 光方向· 法线方向

• // Upgrade NOTE: replaced '_World2Object' with 'unity_WorldToObject'
  
  Shader "LXC/06 Diffuse Fragment HalfLambert"
  {
  	Properties{
  		_Diffuse("Diffuse Color",Color) = (1,1,1,1)
  	}
  		SubShader
  	{
  		Pass{
  		Tags{ "LightMode" = "ForwardBase" }
  		CGPROGRAM
  #include "Lighting.cginc"
  #pragma vertex vert		
  #pragma fragment frag
  		fixed4 _Diffuse;
  
  	struct a2v {
  		float4 vertex:POSITION;
  		float3 normal:NORMAL;
  	};
  
  	struct v2f {
  		float4 position:SV_POSITION;
  		fixed3 worldNormalDir : COLOR0;
  	};
  
  	v2f vert(a2v v) {
  		v2f f;
  		f.position = UnityObjectToClipPos(v.vertex);
  		f.worldNormalDir = mul(v.normal, (float3x3) unity_WorldToObject);
  		return f;
  	}
  
  
  	fixed4 frag(v2f f) :SV_Target{
  		fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.rgb;
  	fixed3 normalDir = normalize(f.worldNormalDir);	
  	fixed3 lightDir = normalize(_WorldSpaceLightPos0.xyz);
  	//半兰伯特公式
  	float halfLambert = dot(normalDir, lightDir) * 0.5 + 0.5;
  	fixed3 diffuse = _LightColor0.rgb * halfLambert *_Diffuse.rgb;
  	fixed3 tempColor = diffuse + ambient;
  	return fixed4(tempColor,1);
  	}
  		ENDCG
  	}
  	}
  		Fallback "Diffuse"	
  }