3D feedback <was 3d member > 2004-03-27 - By NoiseCrime
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-- -- Original Message -- --
From: "Neto" <neto@(protected)>
> > Secondly using copypixels, with a non-dts w3d place in the corner of a
> > 800x600 stage. This managed a very respectable 25 fps in openGL and 20
fps
> > in DX7 on the geforce 2 ultra. Using the radeon9800 it achieved 70 fps
in
> > openGL (DX7 not tested)
>
> So the OGL software render is faster than having DX7 render stuff on
> hardware and transfer it from video memory to system memory.
> Geez, AGP slots really aren't meant to work two ways, really ;)
He, he,
Well i'd say usually harware would be vastly superior to anything, except
this is Director were talking about ;)
Since you can change the scene and get a new image within the same frame,
the member.image property is clearly re-rendering the scene, that explains
some of the drop in performance. Other than that I can't think of any good
reason for such different results. Of course unlike most applications where
you'd usually blit this straight into a texture (and for which cards are
usually more optimised for) sw3d is reading the buffer into a bitmap and
returning it back to lingo, so thats bound to have a hit on performance.
You can speed up copypixels further if you don't need to extract an image
every frame by simply resetting the sprite rect between grabs. That is set
the rect to the size you need the frame before you do copypixels, and then
reset it to say (0,0,8,8) afterwards. Doing that for my shadow projection
demo helpped boost the fps on the geforce 2. I forget why i didn't bother
just moving it off stage though, but i'm sure there was a good reason.
Something that i've not tried yet, but i suspect will be true is grabbing
the image of the w3d member is more or less constant in terms of the time it
takes (based on constant rect), whilst copypixels will suffer as the polygon
count increases. Also as the rect of the image being grabbed increase there
is likely to be a convergance between the two methods.
Noisecrime 2004
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