Explore Core Image kernel improvements

3:54 - Extern CIKernels

// MyKernels.ci.metal
#include <CoreImage/CoreImage.h> // includes CIKernelMetalLib.h

using namespace metal;

extern "C" float4 myKernel (coreimage::sample_t s, 
                            float param, 
                            coreimage::destination dest) 
{
  float4 result = s;
  
  // Example code to create striped pattern
	float diagLine = dest.coord().x + dest.coord().y;
	float stripe   = fract(diagLine/20.0 + param*2.0);
  
  // Color range check
	if((stripe > 0.5) && ((s.r > 1) || (s.g > 1) || (s.b > 1)))
		result = float4(2.0, 0.0, 0.0, 1.0);
  
	return result;
}

4:32 - Load your extern CI kernel and apply it to create a new image

class MyFilter: CIFilter {
    var inputImage: CIImage?
	var inputParam: Float = 0.0
    static var kernel: CIColorKernel = { () -> CIColorKernel in 
	  let url = Bundle.main.url(forResource: "MyKernels", 
                              withExtension: "ci.metallib")!
      let data = try! Data(contentsOf: url)
	  return try! CIColorKernel(functionName: "MyKernel", 
                              fromMetalLibraryData: data)
	}()
	override var outputImage : CIImage? {
      get { guard let input = inputImage else { return nil }
		return MyFilter.kernel.apply(extent:input.extent, 
                                 arguments:[input, inputParam]) }
	}
}

6:18 - Stitchable CI Kernel

// MyKernels.ci.metal
#include <CoreImage/CoreImage.h> // includes CIKernelMetalLib.h

using namespace metal;

[[stitchable]] float4 myKernel (coreimage::sample_t s, 
                                float param, 
                                coreimage::destination d) 
{
  float4 result = s;
  
  // Example code to create striped pattern
	float diagLine = dest.coord().x + dest.coord().y;
	float stripe   = fract(diagLine/20.0 + param*2.0);
  
  // Color range check
	if((stripe > 0.5) && ((s.r > 1) || (s.g > 1) || (s.b > 1)))
		result = float4(2.0, 0.0, 0.0, 1.0);
  
	return result;
}

6:40 - Load your stitchable CI kernel and apply it to create a new image

class MyFilter: CIFilter {
    var inputImage: CIImage?
	var inputParam: Float = 0.0
    static var kernel: CIColorKernel = { () -> CIColorKernel in 
	    let url = Bundle.main.url(forResource: "default", 
                                withExtension: "metallib")!
		let data = try! Data(contentsOf: url)
		return try! CIColorKernel(functionName: "MyKernel", fromMetalLibraryData: data)
	}()
	override var outputImage : CIImage? {
      get { guard let input = inputImage else { return nil }
		return MyFilter.kernel.apply(extent:input.extent, arguments:[input, inputParam]) }
	}
}