added compute

README.md

@@ -35,3 +35,4 @@ Repository to accompany the following blog posts:
 - [Working with Particles in Metal part 3](http://metalkit.org/2017/11/30/working-with-particles-in-metal-part-3.html)
 - [Metal By Tutorials book!](http://metalkit.org/2018/05/29/metal-by-tutorials-book.html)
 - [Raytracing with Metal](http://metalkit.org/2018/07/14/raytracing-with-metal.html)
+- [Introduction to compute using Metal](http://metalkit.org/2019/01/31/intro-to-metal-compute.html)

compute/compute.playground/Contents.swift

@@ -0,0 +1,9 @@
+
+import MetalKit
+import PlaygroundSupport
+
+let frame = NSRect(x: 0, y: 0, width: 800, height: 500)
+let delegate = Renderer()
+let view = MTKView(frame: frame, device: delegate.device)
+view.delegate = delegate
+PlaygroundPage.current.liveView = view

compute/compute.playground/Resources/Shaders.metal

@@ -0,0 +1,11 @@
+
+#include <metal_stdlib>
+using namespace metal;
+
+kernel void compute(texture2d<float, access::read> input [[texture(0)]],
+                    texture2d<float, access::write> output [[texture(1)]],
+                    uint2 id [[thread_position_in_grid]]) {
+    uint2 index = uint2((id.x / 5) * 5, (id.y / 5) * 5);
+    float4 color = input.read(index);
+    output.write(color, id);
+}

compute/compute.playground/Sources/MetalView.swift

@@ -0,0 +1,57 @@
+
+import MetalKit
+
+public class Renderer: NSObject, MTKViewDelegate {
+    
+    public var device: MTLDevice!
+    var queue: MTLCommandQueue!
+    var pipelineState: MTLComputePipelineState!
+    var image: MTLTexture!
+
+    override public init() {
+        super.init()
+        initializeMetal()
+    }
+
+    func initializeMetal() {
+        device = MTLCreateSystemDefaultDevice()
+        queue = device.makeCommandQueue()
+        let textureLoader = MTKTextureLoader(device: device)
+        let url = Bundle.main.url(forResource: "nature", withExtension: "jpg")!
+        guard let file = Bundle.main.path(forResource: "Shaders", ofType: "metal") else { return }
+        do {
+            let source = try String(contentsOfFile: file, encoding: String.Encoding.utf8)
+            let library = try device.makeLibrary(source: source, options: nil)
+            guard let function = library.makeFunction(name: "compute") else { return }
+            pipelineState = try device.makeComputePipelineState(function: function)
+            image = try textureLoader.newTexture(URL: url, options: [:])
+        } catch let error {
+            print(error.localizedDescription)
+        }
+    }
+
+    public func draw(in view: MTKView) {
+        guard let commandBuffer = queue.makeCommandBuffer(),
+              let commandEncoder = commandBuffer.makeComputeCommandEncoder(),
+              let drawable = view.currentDrawable else {
+            return
+        }
+        commandEncoder.setComputePipelineState(pipelineState)
+        commandEncoder.setTexture(image, index: 0)
+        commandEncoder.setTexture(drawable.texture, index: 1)
+        
+        var width = pipelineState.threadExecutionWidth
+        var height = pipelineState.maxTotalThreadsPerThreadgroup / width
+        let threadsPerGroup = MTLSizeMake(width, height, 1)
+        width = Int(view.drawableSize.width)
+        height = Int(view.drawableSize.height)
+        let threadsPerGrid = MTLSizeMake(width, height, 1)
+        commandEncoder.dispatchThreads(threadsPerGrid, threadsPerThreadgroup: threadsPerGroup)
+        
+        commandEncoder.endEncoding()
+        commandBuffer.present(drawable)
+        commandBuffer.commit()
+    }
+
+    public func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {}
+}

compute/compute.playground/contents.xcplayground

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='6.0' target-platform='macos' executeOnSourceChanges='false'/>

compute/compute.playground/playground.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:">
+   </FileRef>
+</Workspace>

compute/compute.playground/playground.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>