Subject:
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Re: LPub Error Message?
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Newsgroups:
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lugnet.cad
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Date:
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Thu, 16 Dec 2010 06:07:29 GMT
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Viewed:
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18093 times
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In lugnet.cad, Scott Wardlaw wrote:
> What does BFC actually do? I have not noticed that it makes anything render
> faster when BFC is enabled...at least not in my limited experience.
>
> I have used the BFC statements to create the normal to the quad / triangle plane
> in the correct direction...for lighting enabled rendering.
>
> So what is culling supposed to make better?
Its main purpose is performance. On my Mac (which has a crappy video card), I
get between 10% and 15% improved frame rate on LDView's 8464.mpd sample model
with default LDView settings vs. the same settings with BFC disabled.
Having said that, LDView's 3DS exporting doesn't work very well with non-BFC
geometry, so I suppose BFC has other uses as well. It's just that performance
is the primary purpose of BFC compliance.
LDView supports lighting on non-BFC parts by telling OpenGL to light both sides.
I don't think Direct3D has the ability to do this, so the only way to light both
sides there is to either use a shader or repeat all the non-BFC geometry twice
(once with each winding, and with back faces of polygons culled). (Note that
modern graphics cards cache 3D geometry as it goes by, so drawing all polygons
twice won't affect the performance by anything near a factor of two.)
--Travis
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Message has 1 Reply:
Message is in Reply To:
 | | Re: LPub Error Message?
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| (...) What does BFC actually do? I have not noticed that it makes anything render faster when BFC is enabled...at least not in my limited experience. I have used the BFC statements to create the normal to the quad / triangle plane in the correct (...) (14 years ago, 16-Dec-10, to lugnet.cad)
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