[Mesa3d-dev] GLX_MESA_render_texture

Brian Paul brian.paul at tungstengraphics.com
Thu Jun 9 08:07:54 PDT 2005

David Reveman wrote:
> On Wed, 2005-06-08 at 11:06 -0700, Ian Romanick wrote: 
>>David Reveman wrote:
>>>I've implemented "render texture"-like support in Xgl. I've used the
>>>GLX_MESA_render_texture name for now but I'm not even sure that we want
>>>to call it something with render_texture.
>>This came up tangentally in the ARB superbuffers group.  Basically,
>>*_render_texture is a misnomer.  You're not rendering to a texture at
>>all.  You're texturing from a drawable.
>>In any case, I don't think adding another *_render_texture extension is
>>the right way to go.  Even before the superbuffers group got started,
>>the ARB dumped the idea of doing a GLX_ARB_render_texture extension.
>>I'll have to think about it, but it seems like it should be possible to
>>layer a window-system extension on GL_EXT_framebuffer_object to achieve
>>this same result.

That's what I was thinking.  GL_EXT_framebuffer_object is the way of 
the future (it'll probably be in OpenGL 2.1).

Isn't it possible to implement top-level windows and pixmaps and 
pbuffers all with framebuffer objects?  I haven't considered this in 
detail but it seems feasible.

Framebuffer objects are also more flexible than conventional drawing 
surfaces since you can attach/detach renderbuffers (color, depth, 
stencil, etc) on the fly.  That might be handy someday.

> As you said *_render_texture is really about texturing from a drawable
> and that's exactly what we like to do. GL_EXT_framebuffer_object is not
> about texturing, hence having a dependency on GL_EXT_framebuffer_object
> for doing this seems like a bad idea to me.
>>Also, I'm pretty sure that ATI ships a version of this in their drivers,
>>and I think Nvidia might as well.

Do you mean GL_*_render_texture or GL_EXT_framebuffer_object?  I don't 
recall seeing the former in either NVIDIA's or ATI's driver.


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