[LSC] BFC Standard - Revision 1

[William Howard]

OK, I'll look at moving the exception text up into the main body.
 
Any thoughts on what needs to be re-worded to remove the last remaining
"current issue" (and a choice of words)

-----Original Message-----
From: lsc-bounces at ldraw.org [mailto:lsc-bounces at ldraw.org] On Behalf Of
Travis Cobbs
Sent: 22 October 2006 22:13
To: LDraw Standards Committee
Subject: Re: [LSC] BFC Standard - Revision 1


The exception text should be moved up into the paragraph that talks about
not using BFC unless all parents are certified.  (Actually, we should reword
it to fit into that paragraph naturally.)

--Travis


On 10/22/06, William Howard <william at howard-family.fsworld.co.uk> wrote: 

OK,

I've just found this in the standard "One important special case is this:
part files are never inverted. Parts are complex files which would be
essentially useless if they were inverted. Assuming part files are never 
inverted allows the rendering engine to apply BFC-processing on certified
parts, even if the calling files (i.e., the main model file(s)) aren't
certified."

So at one point we are saying that a sub-file can't be culled if it's in a 
non-certified super-file, but at another point of the standard we are saying
that we can.

Confused?  You will be!

-----Original Message-----
From: lsc-bounces at ldraw.org  <mailto:lsc-bounces at ldraw.org>
[mailto:lsc-bounces at ldraw.org] On Behalf Of
William Howard
Sent: 22 October 2006 10:30
To: 'LDraw Standards Committee'
Subject: RE: [LSC] BFC Standard - Revision 1 


> On the matter of culling parts even if the super-file isn't certified ...
Thinking some more about this, this *has* to be incorrect.  If it was
correct that you can't BFC a subfile unless the superfile is certified, 
hardly any models would ever be rendered with  culling applied as the main
model file is almost never BFC certified.

I was thinking that perhaps the criterion is if the superfile contains
polygons, but that also can't be true as some of my model files contain raw 
rects and tris to create arrows (and they render correctly in LDView which
Travis says performs back face culling regardless).

So, we seem to have a case that back face culling can be applied if the main
model file or a part file within a superfile is certified.

The problem seems to be with the definition of the term "current reference
branch" - which is used in the definition of culling (under Language 
Extension Functionality) but never defined itself.

(The terms "file-reference tree", "file-reference branch" also need sorting
out)



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