diff --git a/ch08/chapter08.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate b/ch08/chapter08.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate
index ee9d100..2b92eb4 100644
Binary files a/ch08/chapter08.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate and b/ch08/chapter08.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate differ
diff --git a/ch09/chapter09.playground/Resources/Shaders.metal b/ch09/chapter09.playground/Resources/Shaders.metal
index e98195c..f2464b2 100755
--- a/ch09/chapter09.playground/Resources/Shaders.metal
+++ b/ch09/chapter09.playground/Resources/Shaders.metal
@@ -22,5 +22,4 @@ vertex Vertex vertex_func(constant Vertex *vertices [[buffer(0)]], constant Unif
 
 fragment half4 fragment_func(Vertex vert [[stage_in]]) {
     return half4(vert.color);
-//    return half4(0.0, 1.0, 0.0, 1.0);
 }
diff --git a/ch09/chapter09.playground/Sources/MetalView.swift b/ch09/chapter09.playground/Sources/MetalView.swift
index 921a3e6..795b1ae 100755
--- a/ch09/chapter09.playground/Sources/MetalView.swift
+++ b/ch09/chapter09.playground/Sources/MetalView.swift
@@ -71,8 +71,6 @@ public class MetalView: NSObject, MTKViewDelegate {
         let modelMatrix = matrix_multiply(matrix_multiply(rotatedX, rotatedY), scaled)
         let cameraPosition = vector_float3(0, 0, -3)
         let viewMatrix = translationMatrix(position: cameraPosition)
-//        let aspect = Float(view.drawableSize.width / view.drawableSize.height)
-//        let projMatrix = projectionMatrix(0, far: 10, aspect: aspect, fovy: 1)
         let projMatrix = projectionMatrix(near: 0, far: 10, aspect: 1, fovy: 1)
         let modelViewProjectionMatrix = matrix_multiply(projMatrix, matrix_multiply(viewMatrix, modelMatrix))
         let bufferPointer = uniformBuffer.contents()
@@ -93,7 +91,6 @@ public class MetalView: NSObject, MTKViewDelegate {
             commandEncoder.setCullMode(.back)
             commandEncoder.setVertexBuffer(vertexBuffer, offset: 0, at: 0)
             commandEncoder.setVertexBuffer(uniformBuffer, offset: 0, at: 1)
-//            commandEncoder.setTriangleFillMode(.lines)
             commandEncoder.drawIndexedPrimitives(type: .triangle, indexCount: indexBuffer.length / MemoryLayout<UInt16>.size, indexType: MTLIndexType.uint16, indexBuffer: indexBuffer, indexBufferOffset: 0)
             commandEncoder.endEncoding()
             commandBuffer.present(drawable)
diff --git a/ch09/chapter09.playground/contents.xcplayground b/ch09/chapter09.playground/contents.xcplayground
index 06828af..9f9eecc 100644
--- a/ch09/chapter09.playground/contents.xcplayground
+++ b/ch09/chapter09.playground/contents.xcplayground
@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='5.0' target-platform='osx'>
+<playground version='5.0' target-platform='osx' executeOnSourceChanges='false'>
     <timeline fileName='timeline.xctimeline'/>
 </playground>
\ No newline at end of file
diff --git a/ch09/chapter09.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate b/ch09/chapter09.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate
index 2061fba..9c3f516 100755
Binary files a/ch09/chapter09.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate and b/ch09/chapter09.playground/playground.xcworkspace/xcuserdata/marius.xcuserdatad/UserInterfaceState.xcuserstate differ