Difference between OpenGL and D3D pixel formats

I'm continuing to try and develop an OpenGL path for my software. I'm using abstract classes with concrete implementations for both, but obviously I need a common pixel format enumerator so that I can describe texture, backbuffer/frontbuffer and render target formats between the two. I provide a function in each concrete implementation that accepts my abstract identifier for say, R8G8B8A8, and provides the concrete implementation with an enum suitable for e开发者_开发知识库ither D3D or OpenGL

I can easily enumerate all D3D pixel formats using CheckDeviceFormat. For OpenGL, I'm firstly iterating through Win32 available accelerated formats (using DescribePixelFormat) and then looking at the PIXELFORMATDESCRIPTOR to see how it's made up, so I can assign it one of my enums. This is where my problems start:

I want to be able to discover all accelerated formats that OpenGL supports on any given system, as comparable to a D3D format. But according to the format descriptors, there aren't any RGB formats (they're all BGR). Further, things like DXT1 - 5 formats, enumerable in D3D, aren't enumerable using the above method. For the latter, I suppose I can just assume if the extension is available, it's a hardware accelerated format.

For the former (how to interpret the format descriptor in terms of RGB/BGR, etc.), I'm not too sure how it works.

Anyone know about this stuff?

Responses appreciated.

Ok, I think I found what I was looking for:

OpenGL image formats

Some image formats are defined by the spec (for backbuffer/depth-stencil, textures, render-targets, etc.), so there is a guarantee, to an extent, that these will be available (they don't need enumerating). The pixel format descriptor can still be used to work out available front buffer formats for the given window.