[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(1, 0, 0, 0);
                #ifdef MY_multi_1
                col = fixed4(0, 1, 0, 0);
                #endif
                #ifdef MY_multi_2
                col = fixed4(0, 0, 1, 0);
                #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(1, 0, 0, 0);
                #ifdef MY_multi_3
                col = fixed4(1, 1, 1, 0);
                #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");
        }
    }
}