渐变纹理

fixed halfLambert = 0.5 * dot(worldNormal, worldLightDir) + 0.5;
fixed3 diffuseColor = tex2D(_RampTex, fixed2(halfLambert, halfLambert)).rgb * _Color.rgb;

关键代码有两行

• 第一行代码获得了法线和光线方向的夹角的余弦值*0.5 + 0.5, 即把余弦值映射到[0, 1]。
• 第二行代码在渐变纹理上采样

Shader "UnityShaderLearning/RampTexture" 
{
	Properties
	{
		_Color ("Color Tint", Color) = (1,1,1,1)
		_RampTex ("Ramp Tex", 2D) = "white" {}
		_Specular ("Specular", Color) = (1, 1, 1, 1)
		_Gloss ("Gloss", Range(8.0, 256)) = 20
	}
	SubShader
	{
		Pass
		{
			Tags { "LightMode"="ForwardBase" }
			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag
			#include "Lighting.cginc"

			fixed4 _Color;
			sampler2D _RampTex;
			float4 _RampTex_ST;
			fixed4 _Specular;
			float _Gloss;

			struct a2v
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 pos : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
				float2 uv : TEXCOORD2;
			};

			v2f vert(a2v v)
			{
				v2f o;
				o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				o.worldPos = mul(_Object2World, v.vertex).xyz;
				o.uv = TRANSFORM_TEX(v.texcoord, _RampTex);
				return o;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				fixed3 worldNormal = normalize(i.worldNormal);
				fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));
				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz;
				fixed halfLambert = 0.5 * dot(worldNormal, worldLightDir) + 0.5;
				fixed3 diffuseColor = tex2D(_RampTex, fixed2(halfLambert, halfLambert)).rgb * _Color.rgb;
				fixed3 diffuse = _LightColor0.rgb * diffuseColor;
				fixed3 viewDir = normalize(UnityWorldSpaceViewDir(i.worldPos));
				fixed3 halfDir = normalize(worldLightDir + viewDir);
				fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(worldNormal, halfDir)), _Gloss);

				return fixed4(ambient + diffuse + specular, 1.0);
			}
			ENDCG
		}
	}
	FallBack "Diffuse"
}

赏

谢谢你请我吃糖果