Open Radar

 
Summary:
I've been working with DTS trying to use CAOpenGLLayer effectively. (Follow-Up: 165216028)

I am rendering to an offscreen FBO and trying to then render it in the drawInContext: callback of CAOpenGLLayer. This works perfectly fine on for me except when there is no display connected to the Mac. In the headless Mac case, I get no rendering/

DTS seems to think this is a specific bug to CAOpenGLLayer (but not NSOpenGLView) and asked me to file a bug.

With my real program, I do notice that on Lion, if I kick into fullscreen mode, I start to get things rendered. Also, if I do weird things to my window (programatic reshape) which force complicated redraws in my engine, I sometimes get a single frame rendered to the screen which then remains stuck until I do it again or switch to fullscreen.

Steps to Reproduce:
Attached is a demo program DTS originally sent to me. It is tweaked a little, but I think it is mostly the same and never worked with offscreen rendering. I was hoping to reproduce the Lion fullscreen effect with it, but was not able to. Still, I think you will be able to see the fundamental drawing problem. It should draw a spinning diamond on the screen under normal circumstances.

To reproduce the problem, detach all displays from your computer. (I use a Mac Mini mid 2010.) 
Then reboot. 
Then run the program.




Expected Results:
You should see a spinning diamond.

Actual Results:
I think you either see a black window or a red window. I can't remember which. I think the color might be the glClearColor.


Regression:
Both Snow Leopard and Lion have problems.
On Snow Leopard, my pixel format is rejected if I request accelerated and no recovery, and omit kCGLPFARemotePBuffer and my programs eventually crash, but it is accepted on Lion. On Snow Leopard, if I try a fallback with kCGLPFARemotePBuffer (instructed by DTS), I avoid a crash, but get no rendering.

Notes: