added chapter 14

README.md

@@ -14,4 +14,5 @@ Repository to accompany the following blog posts:
 - [Using MetalKit part 10](http://mhorga.org/2016/05/02/using-metalkit-part-10.html)
 - [Using MetalKit part 11](http://mhorga.org/2016/05/10/using-metalkit-part-11.html)
 - [Using MetalKit part 12](http://mhorga.org/2016/05/18/using-metalkit-part-12.html)
-- [Using MetalKit part 13](http://mhorga.org/2016/05/25/using-metalkit-part-13.html)
+- [Using MetalKit part 13](http://mhorga.org/2016/05/25/using-metalkit-part-13.html)
+- [Using MetalKit part 14](http://mhorga.org/2016/06/01/using-metalkit-part-14.html)

ch14/chapter14.playground/Contents.swift

@@ -0,0 +1,8 @@
+
+import Cocoa
+import XCPlayground
+
+let device = MTLCreateSystemDefaultDevice()!
+let frame = NSRect(x:0, y:0, width:400, height:400)
+let view = MetalView(frame: frame, device: device)
+XCPlaygroundPage.currentPage.liveView = view

ch14/chapter14.playground/Resources/Shaders.metal

@@ -0,0 +1,49 @@
+
+#include <metal_stdlib>
+
+using namespace metal;
+
+float random(float2 p)
+{
+    return fract(sin(dot(p, float2(15.79, 81.93)) * 45678.9123));
+}
+
+float noise(float2 p)
+{
+    float2 i = floor(p);
+    float2 f = fract(p);
+    f = f * f * (3.0 - 2.0 * f);
+    float bottom = mix(random(i + float2(0)), random(i + float2(1.0, 0.0)), f.x);
+    float top = mix(random(i + float2(0.0, 1.0)), random(i + float2(1)), f.x);
+    float t = mix(bottom, top, f.y);
+    return t;
+}
+
+float fbm(float2 uv)
+{
+    float sum = 0;
+    float amp = 0.7;
+    for(int i = 0; i < 4; ++i)
+    {
+        sum += noise(uv) * amp;
+        uv += uv * 1.2;
+        amp *= 0.4;
+    }
+    return sum;
+}
+
+kernel void compute(texture2d<float, access::write> output [[texture(0)]],
+                    constant float2 &mouse [[buffer(0)]],
+                    constant float &timer [[buffer(1)]],
+                    uint2 gid [[thread_position_in_grid]])
+{
+    int width = output.get_width();
+    int height = output.get_height();
+    float2 uv = float2(gid) / float2(width, height);
+    uv = uv * 2.0 - 1.0;
+    float radius = 0.5;
+    float distance = length(uv) - radius;
+    uv = fmod(uv + float2(timer * 0.2, 0), float2(width, height));
+    float t = fbm( uv * 3 );
+    output.write(distance < 0 ? float4(float3(t), 1) : float4(0), gid);
+}

ch14/chapter14.playground/Sources/MetalView.swift

@@ -0,0 +1,70 @@
+
+import MetalKit
+
+public class MetalView: MTKView, NSWindowDelegate {
+
+    var queue: MTLCommandQueue! = nil
+    var cps: MTLComputePipelineState! = nil
+    var timer: Float = 0
+    var timerBuffer: MTLBuffer!
+    var mouseBuffer: MTLBuffer!
+    var pos: NSPoint!
+
+    override public func mouseDown(event: NSEvent) {
+        pos = convertPointToLayer(convertPoint(event.locationInWindow, fromView: nil))
+        let scale = layer!.contentsScale
+        pos.x *= scale
+        pos.y *= scale
+    }
+
+    required public init(coder: NSCoder) {
+        super.init(coder: coder)
+    }
+
+    override public init(frame frameRect: CGRect, device: MTLDevice?) {
+        super.init(frame: frameRect, device: device)
+        registerShaders()
+    }
+
+    override public func drawRect(dirtyRect: NSRect) {
+        if let drawable = currentDrawable {
+            let commandBuffer = queue.commandBuffer()
+            let commandEncoder = commandBuffer.computeCommandEncoder()
+            commandEncoder.setComputePipelineState(cps)
+            commandEncoder.setTexture(drawable.texture, atIndex: 0)
+            commandEncoder.setBuffer(mouseBuffer, offset: 0, atIndex: 2)
+            commandEncoder.setBuffer(timerBuffer, offset: 0, atIndex: 1)
+            update()
+            let threadGroupCount = MTLSizeMake(8, 8, 1)
+            let threadGroups = MTLSizeMake(drawable.texture.width / threadGroupCount.width, drawable.texture.height / threadGroupCount.height, 1)
+            commandEncoder.dispatchThreadgroups(threadGroups, threadsPerThreadgroup: threadGroupCount)
+            commandEncoder.endEncoding()
+            commandBuffer.presentDrawable(drawable)
+            commandBuffer.commit()
+        }
+
+    }
+
+    func update() {
+        timer += 0.01
+        var bufferPointer = timerBuffer.contents()
+        memcpy(bufferPointer, &timer, sizeof(Float))
+        bufferPointer = mouseBuffer.contents()
+        memcpy(bufferPointer, &pos, sizeof(NSPoint))
+    }
+
+    func registerShaders() {
+        queue = device!.newCommandQueue()
+        let path = NSBundle.mainBundle().pathForResource("Shaders", ofType: "metal")
+        do {
+            let input = try String(contentsOfFile: path!, encoding: NSUTF8StringEncoding)
+            let library = try device!.newLibraryWithSource(input, options: nil)
+            let kernel = library.newFunctionWithName("compute")!
+            cps = try device!.newComputePipelineStateWithFunction(kernel)
+        } catch let e {
+            Swift.print("\(e)")
+        }
+        timerBuffer = device!.newBufferWithLength(sizeof(Float), options: [])
+        mouseBuffer = device!.newBufferWithLength(sizeof(NSPoint), options: [])
+    }
+}

ch14/chapter14.playground/contents.xcplayground

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='osx'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

ch14/chapter14.playground/timeline.xctimeline

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+   </TimelineItems>
+</Timeline>