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Mac OS: NSView, OpenTK and NullReferenceException #330

bchavez opened this Issue Jan 4, 2016 · 2 comments


4 participants

bchavez commented Jan 4, 2016


I'm having a hard time getting an NSView (from MonoMac) working with OpenTK working on mac.

I'm working on a Map Editor for a game. My map editor has two GL surfaces as shown below:

Map Editor

Left surface shows loaded terrain textures (via GL) and right side is the 3D rendered map (via GL). On windows and linux everything works perfectly. Both GL surfaces share texture graphic contexts.

Mac, however, has been somewhat of a pain. On the mac platform, both left and right panels are NSViews. I cannot get shared contexts between both surfaces using OpenTK.

Attempt 1

Originally, I tried manually creating an NSOpenGLContext (from MonoMac) and passing it to OpenTK as an externally created context, but didn't get very far. I get a somewhat related issue: #52 where CreateDummyContext that kept throwing a "key not found" exception.

Attempt 2

My current attempt is to try and use CreateMacOSWindowInfo and hopefully have OpenTK manage both graphics contexts automatically. However, my current attempt runs into a NullReferenceException when I use any of the GL methods like GL.ClearColor. My current code is here:

public void InitGL()
  OpenTK.Graphics.GraphicsContext.ShareContexts = true;

  var gpxMode = GraphicsMode.Default;

    this.windowInfo = OpenTK.Platform.Utilities.CreateMacOSWindowInfo(this.Window.Handle, this.Handle);

  this.openTK = new OpenTK.Graphics.GraphicsContext(gpxMode, this.windowInfo, 1, 0, GraphicsContextFlags.ForwardCompatible);


  //Null Reference Exception Here

  this.IsInitialized = true;


My guess is, OpenTK didn't setup the GraphicsContext I received correctly, somewhere.

My open source project can be found here:

I'd appreciate it if anyone could help me solve this issue.



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varon Jun 11, 2017


@UnknownShadow200 - here's a mac issue that would be worth looking at.


varon commented Jun 11, 2017

@UnknownShadow200 - here's a mac issue that would be worth looking at.


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UnknownShadow200 Jun 12, 2017


UnknownShadow200 commented Jun 12, 2017

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