[UnityShader基础]06.#pragma multi_compile

参考链接：

https://blog.csdn.net/qq826364410/article/details/81774741

https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html

1.#pragma multi_compile MY_multi_1 MY_multi_2

定义了两个shader关键字，一个是MY_multi_1，另一个是MY_multi_2

MultiCompile.shader

 Shader "Custom/MultiCompile"
 {
     SubShader
     {
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma multi_compile MY_multi_1 MY_multi_2

             #include "UnityCG.cginc"

             struct appdata
             {
                 float4 vertex : POSITION;
             };

             struct v2f
             {
                 float4 vertex : SV_POSITION;
             };

             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                 return o;
             }

             fixed4 frag (v2f i) : SV_Target
             {
                 fixed4 col = fixed4(, , , );
                 #ifdef MY_multi_1
                 col = fixed4(, , , );
                 #endif
                 #ifdef MY_multi_2
                 col = fixed4(, , , );
                 #endif
                 return col;
             }
             ENDCG
         }
     }
 }

测试如下，来回按下QW，即可以看到两种颜色的切换

 using UnityEngine;

 public class MultiCompile : MonoBehaviour {

     void Update ()
     {
         if (Input.GetKeyDown(KeyCode.Q))
         {
             Shader.EnableKeyword("MY_multi_1");
             Shader.DisableKeyword("MY_multi_2");
         }
         else if(Input.GetKeyDown(KeyCode.W))
         {
             Shader.EnableKeyword("MY_multi_2");
             Shader.DisableKeyword("MY_multi_1");
         }
     }
 }

2.#pragma multi_compile __ MY_multi_3

定义了一个shader关键字，MY_multi_3

MultiCompile2.shader

 Shader "Custom/MultiCompile2"
 {
     SubShader
     {
         Pass
         {
             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             #pragma multi_compile __ MY_multi_3

             #include "UnityCG.cginc"

             struct appdata
             {
                 float4 vertex : POSITION;
             };

             struct v2f
             {
                 float4 vertex : SV_POSITION;
             };

             v2f vert (appdata v)
             {
                 v2f o;
                 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                 return o;
             }

             fixed4 frag (v2f i) : SV_Target
             {
                 fixed4 col = fixed4(, , , );
                 #ifdef MY_multi_3
                 col = fixed4(, , , );
                 #endif
                 return col;
             }
             ENDCG
         }
     }
 }

测试如下，来回按下ER，即可以看到两种颜色的切换

 using UnityEngine;

 public class MultiCompile2 : MonoBehaviour {

     void Update ()
     {
         if (Input.GetKeyDown(KeyCode.E))
         {
             Shader.EnableKeyword("MY_multi_3");
         }
         else if (Input.GetKeyDown(KeyCode.R))
         {
             Shader.DisableKeyword("MY_multi_3");
         }
     }
 }