高光反射

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本文深入探讨了Phong和BlinnPhong光照模型在计算机图形学中的应用，详细解析了顶点高光和片元高光反射Shader的实现原理。通过对比Phong与BlinnPhong模型，阐述了两者在高光计算上的差异，为读者提供了全面的光照模型理解和实践指导。

在这里插入图片描述
Phong顶点高光反射Shader

Shader "Unlit/01"
{
	Properties
	{
		_Diffuse("Diffuse", Color) = (1,1,1,1)
		_Specular("Specular", Color) = (1,1,1,1)
		_Gloss("Gloss", Range(1,256)) = 5
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"
			#include "Lighting.cginc"

			fixed4 _Diffuse;
			fixed4 _Specular;
			float _Gloss;

			struct v2f
			{
				float4 vertex : SV_POSITION;
				fixed3 color: Color;
			};

			v2f vert (appdata_base v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				//取得物体顶点的世界位置信息
				fixed3 worldPos = mul(unity_ObjectToWorld, v.vertex);

				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				//世界空间下的法线方向
				fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
				//fixed3 worldLight = normalize(_WorldSpaceLightPos0.xyz);
				//光的方向
				fixed3 worldLight = UnityWorldSpaceLightDir(worldPos);
				//先取得漫反射信息 入射光线颜色和强度*材质漫反射系数*max(0, dot(worldNormal,worldLight))
				fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * max(0, dot(worldNormal,worldLight));
				//reflect(I, N)	根据光源方向和表面法向量N计算反射向量，仅对三元向量有效
				fixed3 reflectDir = normalize(reflect(-worldLight,worldNormal));
				//世界空间坐标下  相机位置-物体顶点位置
				//fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - UnityObjectToWorldDir(v.vertex));
				fixed3 viewDir = normalize(UnityWorldSpaceViewDir(worldPos));
				//fixed3 viewDir = normalize(WorldSpaceViewDir(v.vertex));
				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0,dot(reflectDir,viewDir)),_Gloss);
				//漫反射加环境光加高光
				o.color = diffuse + ambient + specular;
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				return fixed4(i.color,1);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

Phong片元高光反射Shader

Shader "Unlit/02"
{
   Properties
	{
		_Diffuse("Diffuse", Color) = (1,1,1,1)
		_Specular("Specular", Color) = (1,1,1,1)
		_Gloss("Gloss", Range(1,256)) = 5
	}

	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"
			#include "Lighting.cginc"

			fixed4 _Diffuse;
			fixed4 _Specular;
			float _Gloss;

			struct v2f
			{
				float4 vertex : SV_POSITION;
				fixed3 worldNormal: TEXCOORD0;
				float3 worldPos: TEXCOORD1;
			};

			v2f vert (appdata_base v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				fixed3 worldNormal = UnityObjectToWorldNormal( v.normal);
				o.worldNormal = worldNormal;
				o.worldPos =  mul(unity_ObjectToWorld, v.vertex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				//漫反射
				fixed3 worldLightDir = UnityWorldSpaceLightDir(i.worldPos);
				//fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * max(0,dot(worldLightDir,i.worldNormal));

				//高光反射
				fixed3 reflectDir = normalize(reflect(-worldLightDir,i.worldNormal));
				//fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
				fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(saturate(dot(reflectDir,viewDir)),_Gloss);
				
				fixed3 color = ambient + diffuse + specular;
				return fixed4(color,1);
			}
			ENDCG
		}
	}
}

BlinnPhong高光反射

Shader "Unlit/03"
{
   Properties
	{
		_Diffuse("Diffuse", Color) = (1,1,1,1)
		_Specular("Specular", Color) = (1,1,1,1)
		_Gloss("Gloss", Range(1,256)) = 5
	}

	SubShader
	{
		Tags { "RenderType"="Opaque" }
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#include "UnityCG.cginc"
			#include "Lighting.cginc"

			fixed4 _Diffuse;
			fixed4 _Specular;
			float _Gloss;

			struct v2f
			{
				float4 vertex : SV_POSITION;
				fixed3 worldNormal: TEXCOORD0;
				float3 worldPos: TEXCOORD1;
			};

			v2f vert (appdata_base v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				fixed3 worldNormal = UnityObjectToWorldNormal( v.normal);
				o.worldNormal = worldNormal;
				o.worldPos = mul(unity_ObjectToWorld, v.vertex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				//漫反射
				fixed3 worldLightDir = UnityWorldSpaceLightDir(i.worldPos);
				//fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
				fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * max(0,dot(worldLightDir,i.worldNormal));

				//高光反射
				//fixed3 reflectDir = normalize(reflect(-worldLightDir,i.worldNormal));
				fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
				//fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
				fixed3 halfDir = normalize(worldLightDir + viewDir);
				//去Phong光照的区别 
				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(saturate(dot(i.worldNormal,halfDir)),_Gloss);
				
				fixed3 color = ambient + diffuse + specular;
				return fixed4(color,1);
			}
			ENDCG
		}
	}
}