Unity #pragma multi_compile说明

multi_compile

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• 作用
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  • 根据编译选项产生shader变体
  • 避免分支语句导致的性能下降
  • 主要用于在代码中选择shader变体
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• Unity在打包时会把所有multi_compile产生的shader变体都打进包中
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示例shader

Shader "DC/Shader/ShaderLab/MultiCompile" {     Properties     {         _MainTex ("Texture", 2D) = "white" {}         [KeywordEnum(R,G,B)] _CL("ColorSelect", Float) = 0     }     SubShader     {         Tags { "RenderType"="Opaque" }         LOD 100          Pass         {             CGPROGRAM             #pragma vertex vert             #pragma fragment frag                          #pragma multi_compile _CL_R _CL_G _CL_B             //使用 __ 减少一个编译选项，编译选项最多256个             #pragma multi_compile __ DB_ON              #include "UnityCG.cginc"              struct appdata             {                 float4 vertex : POSITION;                 float2 uv : TEXCOORD0;             };              struct v2f             {                 float2 uv : TEXCOORD0;                 float4 vertex : SV_POSITION;             };              sampler2D _MainTex;             float4 _MainTex_ST;              v2f vert (appdata v)             {                 v2f o;                 o.vertex = UnityObjectToClipPos(v.vertex);                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);                 UNITY_TRANSFER_FOG(o,o.vertex);                 return o;             }              fixed4 frag (v2f i) : SV_Target             {                 #if DB_ON                     return fixed4(1,1,0,1);                 #elif _CL_R                     return fixed4(1,0,0,1);                 #elif _CL_G                     return fixed4(0,1,0,1);                 #elif _CL_B                     return fixed4(0,0,1,1);                 #else                     fixed4 col = tex2D(_MainTex, i.uv);                     return col;                 #endif             }             ENDCG         }     } }

示例脚本

using UnityEngine;  namespace DC {   public class MultiCompile : MonoBehaviour   {     public Material mat;      public void OnEnable()     {       mat.EnableKeyword("DB_ON"); //      Shader.EnableKeyword("ON");     }      public void OnDisable()     {       mat.DisableKeyword("DB_ON"); //      Shader.DisableKeyword("DB_ON");     }   } }