[Mono-osx] [MonoMac] OpenGL OpenTK proposal / compromise

[Geoff Norton]

Kenneth,

  I'd like to see this code.  I have a opentk repo on github:

http://github.com/kangaroo/opentk

Could you fork it and land your patches?

Thanks

-g

On 2011-02-13, at 9:47 AM, kjpou wrote:

> Hello all
> 
> Have spent the last two days working on the OpenTK.  Ended in 
> frustration basically.
> 
> Here is what I have:
> 
> OpenTK.Graphics.CoreOpenGL
> 
> Basically all the mappings, delegates, helper methods, ErrorHelper.  It 
> was a copy from the windows OpenTK.Graphics.OpenGL.  The bindings are 
> all there and can load them all from a CglContext which is a new 
> Platform backend OpenGL context I created.
> 
> There are something like 2700 method bindings that are delivered with 
> the Windows OpenGL implementation of which only about 600 are used on 
> the mac.
> 
> I have a platform backend hacked together.  When I say hacked I mean 
> hacked but it all loads fine.  No GUI implementation as it uses the 
> current context created from NSOpenGLContext.  That part works.
> 
> OpenTK.Platform.MacOS
> 
> -> CocoaBindings
> ---> Cgl
> 
> -> CglContext
> -> CocoaApplication
> -> CocoaGLNative
> -> CocoaWindowInfo
> 
> You can create a context.
> 
>                         OpenTK.Platform.IWindowInfo windowInfo
>                                 = 
> OpenTK.Platform.Utilities.CreateMacOSCocoaWindowInfo( mGLContext.Handle );
> 
>                         OpenTK.ContextHandle handle = new 
> OpenTK.ContextHandle( mGLContext.Handle );
> 
>                         OpenTK.Graphics.GraphicsContext context =
>                                 new 
> OpenTK.Graphics.GraphicsContext(handle, windowInfo);
> 
>                        context.MakeCurrent( windowInfo );
> 
> When it starts calling the Delegates for example.
> 
>                         ErrorCode theError = ErrorCode.NoError;
>                         theError = GL.GetError ();
>                         GL.ReadBuffer (ReadBufferMode.Front);
> 
> It is erroring out with errors for the native bindings which I can not 
> figure out because of the all the Delegate calls.  If you call the 
> GLCore methods directly it all works fine but using the OpenTK Delegate 
> way it is not working.
> 
> If someone wants to take what I have and try to get it all working you 
> are more than welcome.  Either way those 600 +/- OpenGL calls are going 
> to have to be gone through and culled out.
> 
> In about one hour I ripped all the mappings from the OpenTK for Cocoa 
> that I wrote and placed them in a separate project with some small 
> modifications and got two MonoMac OpenGL samples working.  One hour vs 
> two days hummmm really a no brainer there for where I would prefer to 
> spend my time.
> 
> I am in the process of going through by hand and only implementing those 
> 600 or so methods by hand to get a MonoMac.CoreOpenGL bindings working 
> based on that one hours work.  Basing it on what I learned from the 
> OpenTK I can have it mapping exactly the same way so if someone gets the 
> OpenTK working it should be just a change of library.  What I mean by 
> that is that all one would have to do to use the OpenTK is include it in 
> the project because the naming of the parameters will be exactly the 
> same as those you will already be using for the MonoMac.CoreOpenGL bindings.
> 
> So the following code below would work with OpenTK as well as the 
> MonoMac.CoreOpenGL bindings.  Technically the same code would work for 
> any other OpenTK based program as well.
> 
>                         ErrorCode theError = ErrorCode.NoError;
> 
>                         // select front buffer as our source for pixel data
>                         GL.ReadBuffer (ReadBufferMode.Front);
> 
>                         //Read OpenGL context pixels directly.
> 
>                         // For extra safety, save & restore OpenGL 
> states that are changed
>                         GL.PushClientAttrib 
> (ClientAttribMask.ClientPixelStoreBit);
> 
>                         GL.PixelStore 
> (PixelStoreParameter.PackAlignment, 4); /* Force 4-byte alignment */
>                         GL.PixelStore 
> (PixelStoreParameter.PackRowLength, 0);
>                         GL.PixelStore 
> (PixelStoreParameter.PackSkipRows, 0);
>                         GL.PixelStore 
> (PixelStoreParameter.PackSkipPixels, 0);
>                         // Read a block of pixels from the frame buffer
>                         GL.ReadPixels (0, 0, bufferWidth, bufferHeight, 
> PixelFormat.Bgra, PixelType.UnsignedInt8888Reversed, buffer);
> 
>                         GL.PopClientAttrib ();
> 
>                         theError = GL.GetError ();
>                         if (theError != ErrorCode.NoError)
>                                 Console.WriteLine ("OpenGL error {0}", 
> theError);
> 
> 
> Now before I go through with this would like to know if this is an 
> acceptable compromise and would it be worth the effort to be included 
> within the MonoMac bindings.
> 
> If you want the code that I have begun for OpenTK let me know.
> 
> Kenneth
> 
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> Mono-osx mailing list
> Mono-osx at lists.ximian.com
> http://lists.ximian.com/mailman/listinfo/mono-osx