title: SCNShape not drawing with UIBezierPath under certain circumstances
body: <p>I believe this may be an iOS bug, and I've reported it to Apple via Bug Report. I'll post it here in case there's some workaround I can use, or explanation of the cause.</p>
  
  <p>I'm wanting to draw the stroke of a UIBezierPath within SceneKit. I'm using the CGPath <code>copyStrokingWithWidth</code> function, and then creating a <code>SCNShape</code> using the given path.</p>
  
  <p>This works fine for lines with 2 points, but on lines with 3 points, the SCNShape doesn't display anything. I've determined that this is only the case when the <code>lineWidth</code> is more than 0.1. With <code>lineWidth</code> set to 0.1, it displays perfectly.</p>
  
  <pre><code>let strokeBezierPath = UIBezierPath()
  strokeBezierPath.lineWidth = 1
  strokeBezierPath.move(to: CGPoint.zero)
  strokeBezierPath.addLine(to: CGPoint(x: 10, y: 0))
  strokeBezierPath.addLine(to: CGPoint(x: 10, y: 10))
  let cgPath = strokeBezierPath.cgPath.copy(
      strokingWithWidth: strokeBezierPath.lineWidth,
      lineCap: strokeBezierPath.lineCapStyle,
      lineJoin: strokeBezierPath.lineJoinStyle,
      miterLimit: strokeBezierPath.miterLimit)
  
  let bezierPath = UIBezierPath(cgPath: cgPath)
  let shape = SCNShape(path: bezierPath, extrusionDepth: 1)
  shape.firstMaterial?.diffuse.contents = UIColor.blue
  let node = SCNNode(geometry: shape)
  node.position.z = -40
  
  sceneView.scene.rootNode.addChildNode(node)
  </code></pre>
  
  <p>This works fine with:</p>
  
  <ul>
  <li>Just the first 2 points</li>
  <li>Line width of 0.1</li>
  <li>A manually-drawn bezier path covering the same area</li>
  </ul>
  
  <p>Printing the UIBezierPath for line width as 0.1 (does display):</p>
  
  <pre><code>&lt;UIBezierPath: 0x1d00b12e0; &lt;MoveTo {0, 0.050000000000000003}&gt;,
   &lt;LineTo {10, 0.050000000000000003}&gt;,
   &lt;LineTo {9.9499999999999993, 10}&gt;,
   &lt;LineTo {10.050000000000001, 10}&gt;,
   &lt;LineTo {10.050000000000001, 0}&gt;,
   &lt;LineTo {0, -0.050000000000000003}&gt;,
   &lt;LineTo {0, 0.050000000000000003}&gt;,
   &lt;Close&gt;
  </code></pre>
  
  <p>With line width as 0.2 (doesn't display):</p>
  
  <pre><code>&lt;UIBezierPath: 0x1d00b7160; &lt;MoveTo {0, 0.10000000000000001}&gt;,
   &lt;LineTo {10, 0.10000000000000001}&gt;,
   &lt;LineTo {9.9000000000000004, 0}&gt;,
   &lt;LineTo {9.9000000000000004, 10}&gt;,
   &lt;LineTo {10.1, 10}&gt;,
   &lt;LineTo {10.1, 0}&gt;,
   &lt;LineTo {10, -0.10000000000000001}&gt;,
   &lt;LineTo {0, -0.10000000000000001}&gt;,
   &lt;LineTo {0, 0.10000000000000001}&gt;,
   &lt;Close&gt;
  </code></pre>