Hm, my post was a more like “SIGH no FB reads”, than “GRR - I want FB reads”.
I have read the arguments in the paper and sympathize with them, but I still feel that its a serious omission.
[b]
- If you need FB reads because you can’t do traditional fixed function blending to float buffers. IF you could still do fixed function blending to float buffers, are you still interested in FB reads?
[/b]
Yes, I would - its not blending I am interested in - it is serious mulitpass.
2) If you need FB reads because fixed function blending is too limited. IF you could generalize fixed function blending, are you still interested in FB reads?
Still interested ;-). (but if I cant have it this would soothe it a bit)
3) If you need FB reads of color, depth, stencil, WHICH depth and stencil do you want when multisampling? Can you explain (as specifically as you are comfortable with) what you are trying to do?
well, I can see that multisampling pose a problem, since the values that would make sense (to me) would be the NOT multisampled ones (viewing multisample as a postprocess).
As to what I am trying to do, well, I am not
specifically trying to do anything - but a couple of the ideas I have could benefit from FB reads.
They can be implemented using the feedback mechanism of FB -> texture, or render to texture, although this would prevent the polygons to interact through the FB (unless you copy the FB between every polygon), not to mention the lack of elegance that FB reads would give.
I am perfectly aware that shaders using FB reads would take a performance hit, as they would introduce the spatial/temporal order dependency - but maybe the pipe could change into a mode allowing this? Certainly when FB reads are not used, the pipe should not be slowed down by this requirement.
Anyway I think the OpenGl Shading language hits home on all the other subjects than this and all that I am saying is: don’t let this go just because it is impractical to implement.
[This message has been edited by phook (edited 02-27-2003).]
[This message has been edited by phook (edited 02-27-2003).]