我有兴趣远离Xcode,在一个混合语言应用程序的项目中手动编译Metal着色器。
我不知道怎么做。Xcode隐藏了着色器编译的细节以及在运行时将其加载到应用程序中(只需调用device.newDefaultLibrary()
)。这是否可行,还是我必须使用运行时着色器编译来实现我的目的?
我有兴趣远离Xcode,在一个混合语言应用程序的项目中手动编译Metal着色器。
我不知道怎么做。Xcode隐藏了着色器编译的细节以及在运行时将其加载到应用程序中(只需调用device.newDefaultLibrary()
)。这是否可行,还是我必须使用运行时着色器编译来实现我的目的?
通常,您有三种方法在Metal中加载着色器库:
使用来自着色器源代码的运行时着色器编译,通过MTLDevice newLibraryWithSource:options:error:
或newLibraryWithSource:options:completionHandler:
方法。虽然纯粹主义者可能会回避运行时编译,但此选项具有最小的实际开销,因此完全可行。避免选择此选项的主要实际原因可能是为了避免将您的着色器源代码作为应用程序的一部分公开,以保护您的知识产权。
使用MTLLibrary newLibraryWithFile:error:
或newLibraryWithData:error:
方法加载已编译的二进制库。请按照使用命令行工具构建库中的说明,在构建时创建这些单个二进制库。
让Xcode在构建时将各种*.metal
文件编译为默认库可通过MTLDevice newDefaultLibrary
获得。
#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"];
.
.
.