UnityのShader Variantについて調べてみた ref: http://qiita.com/Es_Program/items/79edf9f8fca786b365aa

file0.txt

#pragma multi_compile _ Lighting_ON Lighting_OFF

file1.txt

#ifdef Lighting_ON
    //ライティングONの時の処理
#elif Lighting_OFF
    //ライティングOFFの時の処理
#endif

file2.txt

Shader "Unlit/Test1"
{
    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert_img
            #pragma fragment frag
            #include "UnityCG.cginc"
            #pragma multi_compile RED GREEN BLUE
            #pragma debug

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = float4(0, 0, 0, 1);
                #ifdef RED
                    col = float4(1, 0, 0, 1);
                #elif GREEN
                    col = float4(0, 1, 0, 1);
                #elif BLUE
                    col = float4(0, 0, 1, 1);
                #endif
                return col;
            }
            ENDCG
        }
    }
}

file3.txt

#pragma multi_compile RED GREEN BLUE

file4.txt

#ifdef RED
    col = float4(1, 0, 0, 1);
#elif GREEN
    col = float4(0, 1, 0, 1);
#elif BLUE
    col = float4(0, 0, 1, 1);
#endif

file5.txt

// Compiled shader for custom platforms, uncompressed size: 6.4KB

Shader "Unlit/Test1" {
SubShader { 


 // Stats for Vertex shader:
 //       d3d11 : 4 math
 Pass {
  GpuProgramID 59568
Program "vp" {
SubProgram "d3d11 " {
// Stats: 4 math
Keywords { "RED" }
Bind "vertex" Vertex
Bind "texcoord" TexCoord0
ConstBuffer "UnityPerDraw" 352
Matrix 0 [glstate_matrix_mvp]
BindCB  "UnityPerDraw" 0
"
~省略~
"
}
SubProgram "d3d11 " {
// Stats: 4 math
Keywords { "GREEN" }
Bind "vertex" Vertex
Bind "texcoord" TexCoord0
ConstBuffer "UnityPerDraw" 352
Matrix 0 [glstate_matrix_mvp]
BindCB  "UnityPerDraw" 0
"
~省略~
"
}
SubProgram "d3d11 " {
// Stats: 4 math
Keywords { "BLUE" }
Bind "vertex" Vertex
Bind "texcoord" TexCoord0
ConstBuffer "UnityPerDraw" 352
Matrix 0 [glstate_matrix_mvp]
BindCB  "UnityPerDraw" 0
"
~省略~
"
}
}
Program "fp" {
SubProgram "d3d11 " {
Keywords { "RED" }
"
~省略~
"
}
SubProgram "d3d11 " {
Keywords { "GREEN" }
"
~省略~
"
}
SubProgram "d3d11 " {
Keywords { "BLUE" }
"
~省略~
"
}
}
 }
}
}

file6.txt

using System.Collections;
using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{
  public void OnGUI()
  {
    KeywordButtonGUI("RED");
    KeywordButtonGUI("GREEN");
    KeywordButtonGUI("BLUE");
  }

  private void KeywordButtonGUI(string keyword)
  {
    if(GUILayout.Button(keyword + " : ON"))
      Shader.EnableKeyword(keyword);
    if(GUILayout.Button(keyword + " : OFF"))
      Shader.DisableKeyword(keyword);
    GUILayout.Label(keyword + " Enabled : " + Shader.IsKeywordEnabled(keyword).ToString());
  }
}

file7.txt

#pragma shader_feature FANCY_STUFF

file8.txt

#pragma multi_compile A B C
#pragma multi_compile D E

file9.txt

Shader "Unlit/Test1"
{
    Properties{
        [KeywordEnum(RED,GREEN,BLUE)]
        _COLOR("COLOR KEYWORD", Float) = 0
    }

    SubShader
    {
        Pass
        {
            CGPROGRAM
            #pragma vertex vert_img
            #pragma fragment frag
            #include "UnityCG.cginc"
            #pragma multi_compile _COLOR_RED _COLOR_GREEN _COLOR_BLUE

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            fixed4 frag (v2f i) : SV_Target
            {
                fixed4 col = float4(0, 0, 0, 1);
                #ifdef _COLOR_RED
                    col = float4(1, 0, 0, 1);
                #elif _COLOR_GREEN
                    col = float4(0, 1, 0, 1);
                #elif _COLOR_BLUE
                    col = float4(0, 0, 1, 1);
                #endif
                return col;
            }
            ENDCG
        }
    }
}