How to load black white image into metal texture - ios

Question

I use two methods to load black white image texture in metal as below:
//1.
mtltexture01 = [textureLoader newTextureWithName:#"texture02"
scaleFactor:1.0
bundle:nil
options:textureLoaderOptions
error:&error];
//2.
UIImage *img = [UIImage imageNamed:#"texture02"];
mtltexture01 = [textureLoader newTextureWithCGImage:img.CGImage options:textureLoaderOptions error:&error];
but both crash, the error log is
"Error Domain=MTKTextureLoaderErrorDomain Code=0 "Image decoding
failed" UserInfo={NSLocalizedDescription=Image decoding failed,
MTKTextureLoaderErrorKey=Image decoding failed}",
how to fix this issue? Also if I load the colorful image into metal, it runs.

Answer 1

-(id<MTLTexture>)textureWithName:(NSString*)imgname UsingDevice:(id<MTLDevice>)device {
MTKTextureLoader* textureLoader = [[MTKTextureLoader alloc] initWithDevice:device];
NSDictionary *textureLoaderOptions = #{
MTKTextureLoaderOptionTextureUsage : #(MTLTextureUsageShaderRead),
MTKTextureLoaderOptionTextureStorageMode : #(MTLStorageModePrivate)
};
return [textureLoader newTextureWithName:imgname
scaleFactor:1.0
bundle:nil
options:textureLoaderOptions
error:nil];
}
and in your metal configurations
id<MTLTexture> mtltexture01;
mtltexture01 = [self textureWithName:#"texture02" UsingDevice:device];
Keep in mind texture02 is a filename and the file needs to be available in your apps assets. You can store the image as MTLTexture into your asset in Xcode and so the conversion is done at build time.
Also check if the image contains at least proper opacity and is one of PNG, JPEG, or TIFF format. There is known loader trouble when textures contain only gray/ black colors and 0% transparency is used.
later integrate your texture to the renderEncoder/commandEncoder
screenshot: Xcode Assets Texture Configurator