Re: How to get current renderer for an NSOpenGLView?

FROM : Troy Stephens
DATE : Thu Mar 27 22:09:38 2008

On Mar 26, 2008, at 2:54 PM, Duncan Champney wrote:
> I need to find out the amount of total VRAM and available VRAM in 
> the current renderer before creating a large renderbuffer object, to 
> make sure I don't choke the system in doing it.
>
> I know how to find the current renderer for a given display, but I 
> want the current renderer for my NSOpenGLView. I can get to the core 
> graphics context like this:
>
>  //code is from my NSOpenGLView object, so self refers to an 
> NSOpenGLView
>  NSOpenGLContext* theContext = [self openGLContext];
>  void* the_CGLContext = [theContext CGLContextObj];
>
> But that still doesn't get me to the renderer. What I want to to is 
> get a handle to the current renderer's CGLRendererInfoObj, then use 
> the call:
>
>            CGLDescribeRenderer (theRendererInfoObj, theRendererInex, 
> kCGLRPVideoMemory,
>                                &deviceVRAM);
>
> But I can't for the life of me figure out how to get from my 
> NSOpenGLView to the renderer's CGLRendererInfoObj. I don't want to 
> assume that the openGL view is on the main display, as all the 
> example code I can find does.
>
> Can somebody help me here? I'm going in circles with the 
> documentation, and can't find an answer to this.


On 10.5, you can get the CGLContext's CGLPixelFormat using 
CGLGetPixelFormat(), and get the CGLPixelFormat's kCGLPFARendererID 
using CGLDescribePixelFormat().  From that I think you should be able 
to identify the applicable renderer from among those available. 
That's the most direct route that I'm aware of, but you may be able to 
get a better recommendation from the experts on the Mac-OpenGL list.

--
Troy Stephens
Cocoa Frameworks
Apple, Inc.