ios - 为什么在 SceneKit 着色器修改器中使用 glsl 或定义函数只会产生错误？

Question

每次我尝试编写 SceneKit 着色器修改器时，我都会看到一个粉红色的屏幕和一个充满错误的调试屏幕。根据documents ，我应该能够在 glsl 中编写 SceneKit 着色器修改器，但我得到的只是这些错误，如

error: use of undeclared identifier 'vec3'; did you mean 'vec'?

嗯？为什么我不能使用 vec3？

我试过像这样手动将所有 vec3 转换为 float3

#pragma arguments

float3 myFunction()
{
    return float3(1,1,1);
}

#pragma transparent
#pragma body

float3 myVar = myFunction();

但是我只是得到一个错误

[SceneKit] Error: FATAL ERROR : failed compiling shader:
Error Domain=MTLLibraryErrorDomain Code=3 "Compilation failed: 

program_source:2847:41: error: expected parameter declarator
                                      , constant return& float3
                                        ^
program_source:2847:50: error: expected ')'
                                      , constant return& float3
                                                 ^
program_source:2732:38: note: to match this '('
fragment SCNOutput commonprofile_frag(commonprofile_io                 in                               [[ stage_in  ]]
                                     ^
program_source:3340:2: error: expected function body after function declarator
}
 ^
" UserInfo={NSLocalizedDescription=Compilation failed: 

program_source:2847:41: error: expected parameter declarator
                                      , constant return& float3
                                        ^
program_source:2847:50: error: expected ')'
                                      , constant return& float3
                                                 ^
program_source:2732:38: note: to match this '('
fragment SCNOutput commonprofile_frag(commonprofile_io                 in                               [[ stage_in  ]]
                                     ^
program_source:3340:2: error: expected function body after function declarator
}
 ^
}
2019-08-31 20:30:28.724039-0700 zLab[3725:903320] [SceneKit] Error: FATAL ERROR : failed compiling shader:
Error Domain=MTLLibraryErrorDomain Code=3 "Compilation failed: 

program_source:2847:41: error: expected parameter declarator
                                      , constant return& float3
                                        ^
program_source:2847:50: error: expected ')'
                                      , constant return& float3
                                                 ^
program_source:2732:38: note: to match this '('
fragment SCNOutput commonprofile_frag(commonprofile_io                 in                               [[ stage_in  ]]
                                     ^
program_source:3340:2: error: expected function body after function declarator
}
 ^
" UserInfo={NSLocalizedDescription=Compilation failed: 

program_source:2847:41: error: expected parameter declarator
                                      , constant return& float3
                                        ^
program_source:2847:50: error: expected ')'
                                      , constant return& float3
                                                 ^
program_source:2732:38: note: to match this '('
fragment SCNOutput commonprofile_frag(commonprofile_io                 in                               [[ stage_in  ]]
                                     ^
program_source:3340:2: error: expected function body after function declarator
}
 ^
}

这一切意味着什么？我做错了什么？

Answer 1

#pragma arguments 指令应用于声明从 CPU 客户端代码设置的着色器修改器的参数。

对于自定义函数和帮助程序，您可以使用#pragma statements 指令(另请参阅 Custom Variable Declarations Using Metal With Scene Kit Shader Modifiers )