半兰伯特光照模型

Shader "QStudyShader/Per_Fragment_HalfLambertLaw"
{
    
	Properties{
    

	}
	SubShader{
    
		Pass{
    
			Tags{
     "LightModel" = "ForwardBase"}
			CGPROGRAM
			#include "Lighting.cginc"
			#pragma vertex Vertex
			#pragma fragment Fragment
			struct a2v {
    
				float4 vertex : POSITION;
				float3 normal : NORMAL;
			};
			struct v2f {
    
				float4 pos : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
			};
			v2f Vertex(a2v v) {
    
				v2f o;
				o.pos = UnityObjectToClipPos(v.vertex);
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				return o;
			}
			fixed4 Fragment(v2f i) : SV_TARGET{
    
				//世界空间下的法线方向
				fixed3 worldNormal = normalize(i.worldNormal);
				//世界空间下的光照方向
				fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				//环境光
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				//半兰伯特光照公式
				fixed halfLambert = dot(worldNormal, worldLightDir) * 0.5 + 0.5;
				//漫反射强度
				fixed3 diffuse = _LightColor0.xyz * halfLambert;
				return fixed4(diffuse + ambient, 1.0);
			}
			ENDCG
		}
	}
}