我有兴趣远离Xcode并在项目中为混合语言应用程序手动编译Metal着色器。
但是，我不知道如何做到这一点。 Xcode在运行时隐藏着色器编译和后续加载到应用程序的细节（您只需调用device.newDefaultLibrary()）。这甚至是可能的，还是我必须为我的目的使用运行时着色器编译？
答案 0 :(得分：9)
通常，您有三种方法可以在Metal中加载着色器库：
通过newLibraryWithSource:options:completionHandler:或MTLLibrary newLibraryWithFile:error:方法从着色器源代码中使用运行时着色器编译。尽管纯粹主义者可能会回避运行时编译，但此选项的实际开销很小，因此完全可行。避免此选项的主要实际原因可能是避免将着色器源代码作为应用程序的一部分提供，以保护您的IP。
使用newLibraryWithData:error:或*.metal方法加载已编译的二进制库。按照Using Command Line Utilities to Build a Library中的说明在构建时创建这些单独的二进制库。
让 Xcode 在构建时将各种MTLDevice newDefaultLibrary文件编译到{{1}}提供的默认库中。
答案 1 :(得分：4)
这是从字符串创建顶点和片段程序的实际代码;使用它可以让你在运行时编译着色器（显示在着色器字符串方法之后的代码中）。
为了消除使用转义序列（例如，n ...）的需要，我使用了STRINGIFY宏。为了解决使用双引号的限制，我写了一个块，它接受一个头文件名数组并从中创建import语句。然后将它们插入到适当位置的着色器中;我对include语句做了同样的事情。它简化并加快了有时候相当冗长的列表的插入。
合并此代码不仅允许您根据本地化选择要使用的特定着色器，而且，如有必要，还可以用于更新应用程序的着色器而无需更新应用程序。您只需创建并发送包含着色器代码的文本文件，您的应用程序可以预编程为引用作为着色器源。
#if !defined(_STRINGIFY)
#define __STRINGIFY( _x ) # _x
#define _STRINGIFY( _x ) __STRINGIFY( _x )
#endif
typedef NSString *(^StringifyArrayOfIncludes)(NSArray <NSString *> *includes);
static NSString *(^stringifyHeaderFileNamesArray)(NSArray <NSString *> *) = ^(NSArray <NSString *> *includes) {
NSMutableString *importStatements = [NSMutableString new];
[includes enumerateObjectsUsingBlock:^(NSString * _Nonnull include, NSUInteger idx, BOOL * _Nonnull stop) {
[importStatements appendString:@"#include <"];
[importStatements appendString:include];
[importStatements appendString:@">\n"];
}];
return [NSString new];
};
typedef NSString *(^StringifyArrayOfHeaderFileNames)(NSArray <NSString *> *headerFileNames);
static NSString *(^stringifyIncludesArray)(NSArray *) = ^(NSArray *headerFileNames) {
NSMutableString *importStatements = [NSMutableString new];
[headerFileNames enumerateObjectsUsingBlock:^(NSString * _Nonnull headerFileName, NSUInteger idx, BOOL * _Nonnull stop) {
[importStatements appendString:@"#import "];
[importStatements appendString:@_STRINGIFY("")];
[importStatements appendString:headerFileName];
[importStatements appendString:@_STRINGIFY("")];
[importStatements appendString:@"\n"];
}];
return [NSString new];
};
- (NSString *)shader
{
NSString *includes = stringifyIncludesArray(@[@"metal_stdlib", @"simd/simd.h"]);
NSString *imports = stringifyHeaderFileNamesArray(@[@"ShaderTypes.h"]);
NSString *code = [NSString stringWithFormat:@"%s",
_STRINGIFY(
using namespace metal;
typedef struct {
float scale_factor;
float display_configuration;
} Uniforms;
typedef struct {
float4 renderedCoordinate [[position]];
float2 textureCoordinate;
} TextureMappingVertex;
vertex TextureMappingVertex mapTexture(unsigned int vertex_id [[ vertex_id ]],
constant Uniforms &uniform [[ buffer(1) ]])
{
float4x4 renderedCoordinates;
float4x2 textureCoordinates;
if (uniform.display_configuration == 0 ||
uniform.display_configuration == 2 ||
uniform.display_configuration == 4 ||
uniform.display_configuration == 6)
{
renderedCoordinates = float4x4(float4( -1.0, -1.0, 0.0, 1.0 ),
float4( 1.0, -1.0, 0.0, 1.0 ),
float4( -1.0, 1.0, 0.0, 1.0 ),
float4( 1.0, 1.0, 0.0, 1.0 ));
textureCoordinates = float4x2(float2( 0.0, 1.0 ),
float2( 2.0, 1.0 ),
float2( 0.0, 0.0 ),
float2( 2.0, 0.0 ));
} else if (uniform.display_configuration == 1 ||
uniform.display_configuration == 3 ||
uniform.display_configuration == 5 ||
uniform.display_configuration == 7)
{
renderedCoordinates = float4x4(float4( -1.0, -1.0, 0.0, 1.0 ),
float4( -1.0, 1.0, 0.0, 1.0 ),
float4( 1.0, -1.0, 0.0, 1.0 ),
float4( 1.0, 1.0, 0.0, 1.0 ));
if (uniform.display_configuration == 1 ||
uniform.display_configuration == 5)
{
textureCoordinates = float4x2(float2( 0.0, 1.0 ),
float2( 1.0, 1.0 ),
float2( 0.0, -1.0 ),
float2( 1.0, -1.0 ));
} else if (uniform.display_configuration == 3 ||
uniform.display_configuration == 7)
{
textureCoordinates = float4x2(float2( 0.0, 2.0 ),
float2( 1.0, 2.0 ),
float2( 0.0, 0.0 ),
float2( 1.0, 0.0 ));
}
}
TextureMappingVertex outVertex;
outVertex.renderedCoordinate = float4(uniform.scale_factor, uniform.scale_factor , 1.0f, 1.0f ) * renderedCoordinates[vertex_id];
outVertex.textureCoordinate = textureCoordinates[vertex_id];
return outVertex;
}
fragment half4 displayTexture(TextureMappingVertex mappingVertex [[ stage_in ]],
texture2d<float, access::sample> texture [[ texture(0) ]],
sampler samplr [[sampler(0)]],
constant Uniforms &uniform [[ buffer(1) ]]) {
if (uniform.display_configuration == 1 ||
uniform.display_configuration == 2 ||
uniform.display_configuration == 4 ||
uniform.display_configuration == 6 ||
uniform.display_configuration == 7)
{
mappingVertex.textureCoordinate.x = 1 - mappingVertex.textureCoordinate.x;
}
if (uniform.display_configuration == 2 ||
uniform.display_configuration == 6)
{
mappingVertex.textureCoordinate.y = 1 - mappingVertex.textureCoordinate.y;
}
if (uniform.scale_factor < 1.0)
{
mappingVertex.textureCoordinate.y += (texture.get_height(0) - (texture.get_height(0) * uniform.scale_factor));
}
half4 new_texture = half4(texture.sample(samplr, mappingVertex.textureCoordinate));
return new_texture;
}
)];
return [NSString stringWithFormat:@"%@\n%@", includes, imports, code];
}
/*
* Metal setup: Library
*/
__autoreleasing NSError *error = nil;
NSString* librarySrc = [self shader];
if(!librarySrc) {
[NSException raise:@"Failed to read shaders" format:@"%@", [error localizedDescription]];
}
_library = [_device newLibraryWithSource:librarySrc options:nil error:&error];
if(!_library) {
[NSException raise:@"Failed to compile shaders" format:@"%@", [error localizedDescription]];
}
id <MTLFunction> vertexProgram = [_library newFunctionWithName:@"mapTexture"];
id <MTLFunction> fragmentProgram = [_library newFunctionWithName:@"displayTexture"];
.
.
.