| Re: [AD] Memory Bitmap to Display blit slow? |
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On Sat February 28 2009, Trent Gamblin wrote:
> On Sat, February 28, 2009 2:58 pm, Thomas Fjellstrom said:
> > I've been noticing this for a while now, but under linux, with the nvidia
> > binary drivers, bliting a memory bitmap to a regular allegro 5 display is
> > horrendously slow.
> >
> > Using SiegeLord's ex_prim example, when you change to software mode fps
> > drops to 4fps on my (q6600+8800GTS) system. SiegeLord mentioned once that
> > if you remove the final blit, the fps goes back up to normal, so it is
> > not the software primitive rendering causing the slowdown. I'm confused
> > as to why it would be so slow.
> >
> > I tried setting the new bitmap format before creating the memory bitmap
> > to the current display flags, but if it did help, it wasn't by much,
> > maybe 1fps. So it doesn't seem to be a expensive conversion issue. that
> > leaves texture uploads being really slow, or the copy from the bitmap to
> > a texture compatible data structure being the cause.
> >
> > Anyone else have any ideas? As it is, bliting memory bitmaps to a display
> > is unusable on my system right now.
>
> I believe it was Peter who already filed a bug report on the slowness of
> the memory blenders. They aren't optimized at all. They are very very
> generic. They could be made much faster, which would be easy but
> time consuming considering all the different pixel formats. Assuming
> We do blending with only 1 format (converting to and from that format
> with the conversion functions that exist), we would still need ~16
> optimized memory blenders. So if anyone wants to do that go ahead.
Except turning the blending off doesn't help speed much. All thats left is the
conversion functions that you worked quite a bit on months ago.
> > Also, in a related note, when I turn the same example's blending off, the
> > text disappears and the primitives change brightness.
>
> This is expected, since the text uses alpha blending and the primitives
> are normally translucent.
>
> Trent :{)>
--
Thomas Fjellstrom
tfjellstrom@xxxxxxxxxx