Persistent error with contradictory textureUsage in Metal?

Question

This occurs in my attempts to render metal with a CAMetalLayer, and in a lot of 'Metal By Example' sample code I download. The problem is with the 'texture' I guess, here's some code, I can't provide all of it, but I'll try to provide the most relevant parts. It doesn't accept the texture descriptor, printing this into the console.

failed assertion `MTLTextureDescriptor: Depth, Stencil, DepthStencil, and Multisample textures must be allocated with the MTLStorageModePrivate or MTLStorageModeMemoryless storage mode.'

- (void)buildDepthTexture
{
    CGSize drawableSize = self.layer.drawableSize;
    MTLTextureDescriptor *descriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatDepth32Float
                                                                                          width:drawableSize.width
                                                                                         height:drawableSize.height
                                                                                      mipmapped:NO];
    self.depthTexture = [self.device newTextureWithDescriptor:descriptor]; // Thread 1: signal SIGABRT
    [self.depthTexture setLabel:@"Depth Texture"];
}

Again, this is sample code that presumably worked, but no longer does. So I'm like OK, let's allocate it with private storage mode or some junk. descriptor.storageMode = MTLStorageModePrivate;

But when I do that, the render pass descriptor can't be created in draw.

failed assertion `Texture at depthAttachment has usage (0x01) which doesn't specify MTLTextureUsageRenderTarget (0x04)'

MTLRenderPassDescriptor *renderPass = [self newRenderPassWithColorAttachmentTexture:[drawable texture]];

id<MTLCommandBuffer> commandBuffer = [self.commandQueue commandBuffer];

id<MTLRenderCommandEncoder> commandEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPass]; //Thread 1: signal SIGABRT

Here's the code for newRenderPassWithColorAttachmentTexture.

- (MTLRenderPassDescriptor *)newRenderPassWithColorAttachmentTexture:(id<MTLTexture>)texture
{
    MTLRenderPassDescriptor *renderPass = [MTLRenderPassDescriptor new];

    renderPass.colorAttachments[0].texture = texture;
    renderPass.colorAttachments[0].loadAction = MTLLoadActionClear;
    renderPass.colorAttachments[0].storeAction = MTLStoreActionStore;
    renderPass.colorAttachments[0].clearColor = MBEClearColor;

    renderPass.depthAttachment.texture = self.depthTexture;
    renderPass.depthAttachment.loadAction = MTLLoadActionClear;
    renderPass.depthAttachment.storeAction = MTLStoreActionStore;
    renderPass.depthAttachment.clearDepth = 1.0;

    return renderPass;
}

So basically, it seems two different stages of rendering require two different mutually exclusive conditions to be the case. If one's works, the other doesn't work, and vice versa. Seems impossible, seriously, what am I supposed to do? What gives?

Answer 1

You should provide texture usage description:

    - (void)buildDepthTexture
    {
        CGSize drawableSize = self.layer.drawableSize;
        MTLTextureDescriptor *descriptor = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatDepth32Float
                                                                                              width:drawableSize.width
                                                                                             height:drawableSize.height
                                                                                          mipmapped:NO];
    
        descriptor.storageMode = MTLStorageModePrivate;
        descriptor.usage = MTLTextureUsageRenderTarget | MTLTextureUsageShaderRead | MTLTextureUsageShaderWrite;

        self.depthTexture = [self.device newTextureWithDescriptor:descriptor]; // Thread 1: signal SIGABRT
        [self.depthTexture setLabel:@"Depth Texture"];
    }