@@ -1,7 +1,3 @@
1−// TODO: Refactor update into 2 calls: metalRendering() and textureToImage()
2−// TODO: Use async dispatch to free up main queue
3−// TODO: Use two textures/images to alternate the 2 calls (like OpenGL double buffers)
4−
51// TODO: Make graphics have edges only according to graph (instead of being a complete graph)
62
73// TODO: Interpolate metaball colors
@@ -11,45 +7,92 @@
117import Metal
128import UIKit
139
14−class MetalMetaballRenderer: MetaballRenderer {
10+var i = 0
1511
16− typealias TargetView = UIImageView
12+class MetalMetaballRenderer {
1713
18− var supportsDynamicRendering: Bool { get {
19− return true
20− }
21− }
14+ typealias TargetView = UIImageView
2215
23− let targetView = TargetView()
24− var previousFrame = CGRect.zero
16+ let targetView: TargetView
2517
2618 let context = MTLContext()
27− var renderingTexture: MTLTexture!
28− var imageBuffer: UnsafeMutablePointer<Void>!
19+ var activeComputeContext: MTLComputeContext
20+ var idleComputeContext: MTLComputeContext
2921
3022 let dataSource: MetaballDataSource
3123
32− required init(dataSource: MetaballDataSource) {
24+ let semaphore = dispatch_semaphore_create(2)
25+
26+ enum RendererState {
27+ case Idle
28+ case Running
29+ case Ending
30+ }
31+
32+ var state: RendererState = .Idle {
33+ willSet {
34+ if state == .Idle {
35+ if newValue == .Running {
36+ updateTargetView()
37+ }
38+ }
39+ }
40+ }
41+
42+ required init(dataSource: MetaballDataSource, frame: CGRect) {
3343 self.dataSource = dataSource
44+
45+ targetView = TargetView(frame: frame)
46+
47+ let width = Int(frame.width)
48+ let height = Int(frame.height)
49+ let textureDescriptor =
50+ MTLTextureDescriptor.texture2DDescriptorWithPixelFormat(.BGRA8Unorm, width: width, height: height, mipmapped: false)
51+
52+ let texture1 = context.device.newTextureWithDescriptor(textureDescriptor)
53+ activeComputeContext = MTLComputeContext(size: targetView.size, texture: texture1)
54+ let texture2 = context.device.newTextureWithDescriptor(textureDescriptor)
55+ idleComputeContext = MTLComputeContext(size: targetView.size, texture: texture2)
3456 }
3557
3658 func updateTargetView() {
37− let metaballs = dataSource.metaballs
3859
39− if previousFrame != targetView.frame {
40− previousFrame = targetView.frame
41− updateFrame()
42− }
60+ let timeout = dispatch_time(DISPATCH_TIME_NOW, 1000000000)
61+ dispatch_semaphore_wait(semaphore, timeout)
4362
44− let width = Int(targetView.width)
45− let height = Int(targetView.height)
63+ print("Update \(i++)!")
64+
65+ state = .Ending
4666
47− if renderingTexture == nil {
48− let textureDescriptor =
49− MTLTextureDescriptor.texture2DDescriptorWithPixelFormat(.BGRA8Unorm, width: width, height: height, mipmapped: false)
67+ dispatch_async(dispatch_get_global_queue(Int(QOS_CLASS_USER_INTERACTIVE.rawValue), 0)) { () -> Void in
5068
51− renderingTexture = context.device.newTextureWithDescriptor(textureDescriptor)
69+ let computeContext = self.activeComputeContext
70+ swap(&self.activeComputeContext, &self.idleComputeContext)
71+
72+ // Render graphics to metal texture
73+ self.renderToContext(computeContext)
74+
75+ if self.state != .Running {
76+ self.state = .Idle
77+ } else {
78+ self.updateTargetView()
79+ }
80+
81+ // Transform metal texture into image
82+ let uiimage = self.createImageFromContext(computeContext)
83+
84+ dispatch_semaphore_signal(self.semaphore)
85+
86+ dispatch_async(dispatch_get_main_queue(), { () -> Void in
87+ // Send image to view
88+ self.targetView.image = uiimage
89+ })
5290 }
91+ }
92+
93+ func renderToContext(computeContext: MTLComputeContext) {
94+ let width = Int(targetView.width)
95+ let height = Int(targetView.height)
5396
5497 let kernelFunction: MTLFunction?
5598 let pipeline: MTLComputePipelineState
@@ -63,15 +106,13 @@ class MetalMetaballRenderer: MetaballRenderer {
63106 let threadGroups = MTLSizeMake(width / threadGroupCounts.width,
64107 height / threadGroupCounts.height, 1)
65108
66− // Create up-to-date metaball buffer
67− let metaballInfoBuffer = metaballBuffer(metaballs)
68−
69109 // Send commands to metal and render
70110 let commandBuffer = context.commandQueue.commandBuffer()
71111
72112 let commandEncoder = commandBuffer.computeCommandEncoder()
73113 commandEncoder.setComputePipelineState(pipeline)
74− commandEncoder.setTexture(renderingTexture, atIndex: 0)
114+ commandEncoder.setTexture(computeContext.texture, atIndex: 0)
115+ let metaballInfoBuffer = metaballBuffer()
75116 commandEncoder.setBuffer(metaballInfoBuffer, offset: 0, atIndex: 0)
76117 commandEncoder.dispatchThreadgroups(threadGroups,
77118 threadsPerThreadgroup: threadGroupCounts)
@@ -83,12 +124,11 @@ class MetalMetaballRenderer: MetaballRenderer {
83124 } catch _ {
84125 print("Error!")
85126 }
86−
87− // Transform new metal texture into image
88− targetView.image = image(texture: renderingTexture)
89127 }
90128
91− func image(texture texture: MTLTexture) -> UIImage {
129+ func createImageFromContext(computeContext: MTLComputeContext) -> UIImage {
130+ let texture = computeContext.texture
131+
92132 // Get image info
93133 let imageSize = CGSizeMake(CGFloat(texture.width),
94134 CGFloat(texture.height))
@@ -99,16 +139,16 @@ class MetalMetaballRenderer: MetaballRenderer {
99139 let region = MTLRegionMake2D(0, 0, width, height)
100140
101141 // Allocate the buffer if needed
102− if imageBuffer == nil {
103− imageBuffer = malloc(imageByteCount)
142+ if computeContext.imageBuffer == nil {
143+ computeContext.imageBuffer = malloc(imageByteCount)
104144 }
105145
106146 // Transfer texture info into image buffer
107− texture.getBytes(imageBuffer, bytesPerRow: bytesPerRow,
147+ texture.getBytes(computeContext.imageBuffer, bytesPerRow: bytesPerRow,
108148 fromRegion: region, mipmapLevel: 0)
109149
110150 // Get info for UIImage
111− let provider = CGDataProviderCreateWithData(nil, imageBuffer,
151+ let provider = CGDataProviderCreateWithData(nil, computeContext.imageBuffer,
112152 imageByteCount, nil)
113153 let bitsPerComponent = 8
114154 let bitsperPixel = 32
@@ -129,17 +169,18 @@ class MetalMetaballRenderer: MetaballRenderer {
129169 return image
130170 }
131171
132− func metaballBuffer(metaballs: [Metaball]) -> MTLBuffer {
172+ func metaballBuffer() -> MTLBuffer {
133173 // Create Float array for buffer
134174 // Exclude metaballs far from the view's bounds
135175 let border: CGFloat = 100
176+ let metaballs = self.dataSource.metaballs
136177 var floats: [Float] = metaballs.reduce([Float(0)]) { (var array, metaball) -> [Float] in
137178 let x = CGFloat(metaball.midX)
138179 let y = CGFloat(metaball.midY)
139180 if -border < x ≤ targetView.width + border &&
140− -border < y ≤ targetView.height + border {
141− array.append(Float(x))
142− array.append(Float(y))
181+ -border < y ≤ targetView.height + border {
182+ array.append(Float(x))
183+ array.append(Float(y))
143184 }
144185 return array
145186 }
@@ -148,18 +189,7 @@ class MetalMetaballRenderer: MetaballRenderer {
148189
149190 // Create buffer
150191 let buffer = context.device.newBufferWithBytes(floats, length: floats.count * sizeof(Float), options: .StorageModeShared)
151−
192+
152193 return buffer
153194 }
154−
155− func updateFrame() {
156− if imageBuffer != nil {
157− free(imageBuffer)
158− }
159− imageBuffer = nil
160− }
161−
162− deinit {
163− free(imageBuffer)
164− }
165195}