Re: [forum] xfree will be the best....

[Keith Packard <keithp@keithp.com>]

Around 12 o'clock on Apr 6, Marco Bubke wrote:

> How difficult would it be to layer Render over OpenGL? I really don't 
> know render but it looks to me a little bit like the classic OpenGL 
> raster stage.

That shouldn't be surprising; the intent was to make hardware that 
supports OpenGL able to accelerate most of the Render extension.

However, there are a few operations which OpenGL doesn't efficiently 
accelerate in some implementations, most notably the text operations which 
dominate most 2D interfaces and rendering to off-screen images (pbuffers).

In addition, Render includes per-component (RGBA) compositing to improve
image quality on LCD screens and a few new compositing modes needed for
interactive applications.  The compositing modes should be largely
compatible with OpenGL, but the component-level compositing has no 
equivalent in the OpenGL world that I'm aware of.  Hence, any Render 
implementation is likely to include at least some software component that 
touches the raw pixels for the forseeable future which is difficult to do 
through OpenGL.

-keith