Re: copyCGLContextForPixelFormat
Re: copyCGLContextForPixelFormat
- Subject: Re: copyCGLContextForPixelFormat
- From: Richard Somers <email@hidden>
- Date: Mon, 4 Feb 2008 06:24:19 -0700
On Feb 3, 2008, at 10:37AM, John Harper wrote:
Not really, it sounds like what you're describing should work. If
you use CAOpenGLLayer (either directly or via NSView) you don't need
to use double buffering, that is already taken care of (via a
different mechanism)
I have a very simple test application with a single subclassed
NSOpenGLView view. On an older machine with an ATI Radeon graphic card
(machine meets the official Leopard requirements) the frame rate drops
from 88 fps to 34 fps when switching to layer-backed mode. When I try
Apple's LayerBackedOpenGLView sample code application the same thing
happens, the frame rate drops from from 60 fps to 25 fps when
switching to layer-backed mode.
I noticed with both of these applications that when switching to layer-
backed mode the pixel format was changed from double-buffered to
single-buffered so I thought that might have something to do with the
slow down. But apparently from John's comment this is how Core
Animation is supposed to work.
Now I try the same test on a newer machine with an Intel GMA 950
graphics card. With my very simple test application the frame rate
remains constant at 60 fps when switching to layer-backed mode. With
Apple's LayerBackedOpenGLView sample code application the frame rate
actually increases from 35 fps to 45 fps when switching to layer-
backed mode.
So here is my question. Is there something inherently inconsistent
with the current implementation of a layer-backed OpenGL view that
will cause a slow down in frame rates when used with some graphics
cards or is this a known issue that is being addressed?
Regards,
Richard
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