Metal Framework sur macOS

Question

Je crée un simple affichage de texture qui restitue essentiellement les images vidéo au format BGRA via l'affichage Metal. Je suis les mêmes étapes que celles décrites dans la session Metal WWDC. Mais j'ai des problèmes dans la création de l'encodeur de rendu. Mon code est

id <MTLDevice> device = MTLCreateSystemDefaultDevice(); 
id<MTLCommandQueue> commandQueue = [device newCommandQueue]; 

id<MTLLibrary> library = [device newDefaultLibrary]; 

// Create Render Command Descriptor. 
MTLRenderPipelineDescriptor* renderPipelineDesc = [MTLRenderPipelineDescriptor new]; 
renderPipelineDesc.colorAttachments[0].pixelFormat = MTLPixelFormatBGRA8Unorm; 
renderPipelineDesc.vertexFunction = [library newFunctionWithName:@"basic_vertex"]; 
renderPipelineDesc.fragmentFunction = [library newFunctionWithName:@"basic_fragment"]; 

NSError* error = nil; 
id<MTLRenderPipelineState> renderPipelineState = [device newRenderPipelineStateWithDescriptor:renderPipelineDesc 
                   error:&error]; 

id<MTLCommandBuffer> commandBuffer = [commandQueue commandBuffer]; 

MTLRenderPassDescriptor* renderPassDesc = [MTLRenderPassDescriptor renderPassDescriptor]; 

id<CAMetalDrawable> drawable = [_metalLayer nextDrawable]; 

MTLRenderPassColorAttachmentDescriptor* colorAttachmentDesc = [MTLRenderPassColorAttachmentDescriptor new]; 
colorAttachmentDesc.texture = drawable.texture; 
colorAttachmentDesc.loadAction = MTLLoadActionLoad; 
colorAttachmentDesc.storeAction = MTLStoreActionStore; 
colorAttachmentDesc.clearColor = MTLClearColorMake(0, 0, 0, 1); 

[renderPassDesc.colorAttachments setObject:colorAttachmentDesc atIndexedSubscript:0]; 

[inTexture replaceRegion:region 
     mipmapLevel:0 
      withBytes:imageBytes 
     bytesPerRow:CVPixelBufferGetBytesPerRow(_image)]; 

id<MTLRenderCommandEncoder> renderCmdEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDesc]; 

[renderCmdEncoder setRenderPipelineState:_renderPipelineState]; 
[renderCmdEncoder endEncoding]; 

Ce plantages de code dans la ligne en disant "Non Render cibles trouvées" id = renderCmdEncoder [commandBuffer renderCommandEncoderWithDescriptor: renderPassDesc]; Je ne suis pas en mesure de déterminer où et comment définir la cible de rendu.

Answer 1

Cela fonctionnera parfaitement; si vous avez besoin d'aide mise en œuvre, laissez-moi savoir:

@import UIKit; 
@import AVFoundation; 
@import CoreMedia; 
#import <MetalKit/MetalKit.h> 
#import <Metal/Metal.h> 
#import <MetalPerformanceShaders/MetalPerformanceShaders.h> 

@interface ViewController : UIViewController <MTKViewDelegate, AVCaptureVideoDataOutputSampleBufferDelegate> { 
    NSString *_displayName; 
    NSString *serviceType; 
} 

@property (retain, nonatomic) SessionContainer *session; 
@property (retain, nonatomic) AVCaptureSession *avSession; 

@end; 

#import "ViewController.h" 

@interface ViewController() { 
    MTKView *_metalView; 

    id<MTLDevice> _device; 
    id<MTLCommandQueue> _commandQueue; 
    id<MTLTexture> _texture; 

    CVMetalTextureCacheRef _textureCache; 
} 

@property (strong, nonatomic) AVCaptureDevice *videoDevice; 
@property (nonatomic) dispatch_queue_t sessionQueue; 

@end 

@implementation ViewController 

- (void)viewDidLoad { 
    NSLog(@"%s", __PRETTY_FUNCTION__); 
    [super viewDidLoad]; 

    _device = MTLCreateSystemDefaultDevice(); 
    _metalView = [[MTKView alloc] initWithFrame:self.view.bounds]; 
    [_metalView setContentMode:UIViewContentModeScaleAspectFit]; 
    _metalView.device = _device; 
    _metalView.delegate = self; 
    _metalView.clearColor = MTLClearColorMake(1, 1, 1, 1); 
    _metalView.colorPixelFormat = MTLPixelFormatBGRA8Unorm; 
    _metalView.framebufferOnly = NO; 
    _metalView.autoResizeDrawable = NO; 

    CVMetalTextureCacheCreate(NULL, NULL, _device, NULL, &_textureCache); 

    [self.view addSubview:_metalView]; 

    self.sessionQueue = dispatch_queue_create("session queue", DISPATCH_QUEUE_SERIAL); 

    if ([self setupCamera]) { 
     [_avSession startRunning]; 
    } 
} 

- (BOOL)setupCamera { 
    NSLog(@"%s", __PRETTY_FUNCTION__); 
    @try { 
     NSError * error; 

      _avSession = [[AVCaptureSession alloc] init]; 
      [_avSession beginConfiguration]; 
      [_avSession setSessionPreset:AVCaptureSessionPreset640x480]; 

      // get list of devices; connect to front-facing camera 
      self.videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; 
      if (self.videoDevice == nil) return FALSE; 

      AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:self.videoDevice error:&error]; 
      [_avSession addInput:input]; 

      dispatch_queue_t sampleBufferQueue = dispatch_queue_create("CameraMulticaster", DISPATCH_QUEUE_SERIAL); 

      AVCaptureVideoDataOutput * dataOutput = [[AVCaptureVideoDataOutput alloc] init]; 
      [dataOutput setAlwaysDiscardsLateVideoFrames:YES]; 
      [dataOutput setVideoSettings:@{(id)kCVPixelBufferPixelFormatTypeKey: @(kCVPixelFormatType_32BGRA)}]; 
      [dataOutput setSampleBufferDelegate:self queue:sampleBufferQueue]; 

      [_avSession addOutput:dataOutput]; 
      [_avSession commitConfiguration]; 
    } @catch (NSException *exception) { 
     NSLog(@"%s - %@", __PRETTY_FUNCTION__, exception.description); 
     return FALSE; 
    } @finally { 
     return TRUE; 
    } 

} 

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection 
{ 
    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
    { 
     size_t width = CVPixelBufferGetWidth(pixelBuffer); 
     size_t height = CVPixelBufferGetHeight(pixelBuffer); 

     CVMetalTextureRef texture = NULL; 
     CVReturn status = CVMetalTextureCacheCreateTextureFromImage(kCFAllocatorDefault, _textureCache, pixelBuffer, NULL, MTLPixelFormatBGRA8Unorm, width, height, 0, &texture); 
     if(status == kCVReturnSuccess) 
     { 
      _metalView.drawableSize = CGSizeMake(width, height); 
      _texture = CVMetalTextureGetTexture(texture); 
      _commandQueue = [_device newCommandQueue]; 
      CFRelease(texture); 
     } 
    } 
} 

- (void)drawInMTKView:(MTKView *)view { 
    // creating command encoder 
    if (_texture) { 
     id<MTLCommandBuffer> commandBuffer = [_commandQueue commandBuffer]; 
     id<MTLTexture> drawingTexture = view.currentDrawable.texture; 

     // set up and encode the filter 
     MPSImageGaussianBlur *filter = [[MPSImageGaussianBlur alloc] initWithDevice:_device sigma:5]; 

     [filter encodeToCommandBuffer:commandBuffer sourceTexture:_texture destinationTexture:drawingTexture]; 

     // committing the drawing 
     [commandBuffer presentDrawable:view.currentDrawable]; 
     [commandBuffer commit]; 
     _texture = nil; 
    } 
} 

- (void)mtkView:(MTKView *)view drawableSizeWillChange:(CGSize)size { 

} 

@end 

Answer 2

vous devriez essayer l'un des éléments suivants

1.Instead de créer de nouveaux rendu descripteur de passe, utilisez l'objet descripteur de passe rendu en cours de MTKView object.this rendre le descripteur de passe sera déjà configured.you besoin d'être pas réglé anything.try le code exemple donné ci-dessous-

if let currentPassDesc = view.currentRenderPassDescriptor, 
let currentDrawable = view.currentDrawable 
{ 
let renderCommandEncoder =   

commandBuffer.makeRenderCommandEncoder(descriptor: currentPassDesc) 


renderCommandEncoder.setRenderPipelineState(renderPipeline) 

//set vertex buffers and call draw apis 
....... 
....... 
commandBuffer.present(currentDrawable) 

} 

2.you créent un nouveau descripteur de rendu passe, puis définir son attachement couleur par la texture de l'objet drawable donc au lieu de doi Vous devez créer un nouvel objet de texture, puis définir l'utilisation de cette texture comme rendu cible. Le contenu sera rendu dans votre nouvelle texture mais il ne sera pas affiché à l'écran, donc vous devrez afficher le contenu de votre texte. copier le contenu de votre texture dans la texture drawable, puis présente drawable.

ci-dessous est le code de faire rendre la cible -

renderPassDescriptor.colorAttachments[0].clearColor = 

MTLClearColor(red: 

0.0,green: 0.0,blue: 0.0,alpha: 1.0) 
renderPassDescriptor.colorAttachments[0].loadAction = .clear 
renderPassDescriptor.colorAttachments[0].storeAction = .store 

renderPassDescriptor.depthAttachment.clearDepth = 1.0 
renderPassDescriptor.depthAttachment.loadAction = .clear 
renderPassDescriptor.depthAttachment.storeAction = .dontCare 

let view = self.view as!MTKView 
let textDesc = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: 

.bgra8Unorm, width: Int(view.frame.width), 
height: Int(view.frame.height), mipmapped: false) 
textDesc.depth = 1 
//see below line  
textDesc.usage = 
[MTLTextureUsage.renderTarget,MTLTextureUsage.shaderRead] 
textDesc.storageMode = .private 
mainPassFrameBuffer = device.makeTexture(descriptor: textDesc) 
renderPassDescriptor.colorAttachments[0].texture = mainPassFrameBuffer