Subject:
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Re: *** LDView Version 1.9.5 Released ***
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Newsgroups:
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lugnet.cad
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Date:
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Thu, 1 Aug 2002 16:43:31 GMT
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Viewed:
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716 times
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In lugnet.cad, Martijn Zwaal writes:
> Nice to see that everything is ok. Those arms need to be fixed anyway. In
> the mean time I tried to speed up rendering using the vertex array range and
> fences extension on a geforce3. This seems to be about as fast as display
> lists but uses less memory. In the case of smooth sufaces indices can be
> shared due to vertex cache. I could make a speedup by sorting vertices
> spatially. I also discovered in a document in the nvidia sdk that 2 sided
> lighting is almost for free on geforce3 products or higher in the case of
> 'infinite viewer/light source'. Another advantage of using 'infinite
> viewer/light source' is that you don't have to tesselate surfaces for
> acceptable lighting. This is not done with the bricks on the cover of the
> red opengl book and the shading looks a bit strange.
I plan to eventually try out vertex array range, but since it's
nVidia-specific, there has to be a fallback. I hadn't thought about the
decrease in memory consumption, but considering the huge amount of memory
sucked up by the display lists, this is a very good point.
As for two-sided lighting, I think their claim is very very false, but I'll
have to check it out. In LDView, if you select the "High Quality" check box
for lighting, you get a local viewer light source. If you unselect it you
get an infinite viewer light source (both are directional, so the lights
themselves are infinite). If you have "Specular highlight" enabled, LDView
always uses two-sided lighting. However, if it is disabled, you can switch
back and forth between two-lighting and two one-sided lights.
So, with specular disabled, if you select "Alternate setup" you get
two-sided lighting. If you unselect it, you get two one-sided lights
(pointing in opposite directions) instead. The two one-sided lights seem to
be significantly faster, but aren't compatible with specular, so two-sided
lighting is always used if specular is enabled. I don't remember whether or
not I tried with High quality both enabled and disabled, though. Maybe the
default setup is only faster if High quality (local viewer) is enabled.
Incidently, this quirk of two one-sided lights being faster than one
two-sided light means that although specular would normally be free on most
hardware, it actually slows LDView down. (Or, more accurately, the lack of
specular allows LDView to speed up.)
--Travis Cobbs (tcobbs@REMOVE.halibut.com)
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Message is in Reply To:
 | | Re: *** LDView Version 1.9.5 Released ***
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| Nice to see that everything is ok. Those arms need to be fixed anyway. In the mean time I tried to speed up rendering using the vertex array range and fences extension on a geforce3. This seems to be about as fast as display lists but uses less (...) (22 years ago, 1-Aug-02, to lugnet.cad)
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