Subject:
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Re: Latest BFC Spec?
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Newsgroups:
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lugnet.cad.dev
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Date:
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Sat, 22 Mar 2003 00:26:31 GMT
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Viewed:
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798 times
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In lugnet.cad.dev, Travis Cobbs wrote:
> The spec should probably be updated to reflect this, I suppose. Please note
> that this comment and everything below is meant as constructive criticism.
> It's not meant as a complaint or a slight. I'd just like to see the spec
> improved.
Absolutely. :) The spec was never ratified or 'officially' accepted as a
standard. Parts of it are have definitely evolved as the defacto standard,
but that's not the same as having a good, documented standard to follow.
I think the spec can be summed up (for parts authors) as "wind your
polygons, and invert subfiles as necessary". Too bad it takes so much
verbiage to say that...
> I'll even incorporate my suggested modifications and post an
> updated version of the spec for people to review if you'd like.
If you want to update the spec (assuming you haven't already, and I just
haven't gotten to it yet), that would be great. I will put my suggestions
for re-wording below.
> The above is not at all clear with the current spec. The current wording
> strongly implies that CLIP and NOCLIP are file-global, not action statements
> that depend on their placement in the file.
Good point.
> For example:
>
> 4 Clipping. It must be possible for a file to enable and disable clipping. But
> 4 even when clipping is enabled locally, it may not be possible to perform
> 4 clipping on the file in some circumstances. Any file will have clipping
> 4 applied only when the following conditions apply:
How about:
11 Clipping. It must be possible for a enable and disable clipping during
the
11 processing of a file. But even when clipping is currently enabled, it
may not
11 be possible to actually clip on polygons. Polygons can be tested for
11 clipping only when the following conditions apply:
> All references are to the file, not lines in the file. Another:
>
> 4 If the clipping state is modified, it will only affect the clip-state of the
> 4 local file.
>
> Key here is "local file". Not "triangle/quad lines following the statement
> in the local file".
Right. How about:
11 If the clipping state is modified, it affect all lines following the
11 CLIP/NOCLIP statement, until the end of the current file or another
11 CLIP/NOCLIP statement is encountered.
> It should also be noted that setting NOCLIP does indeed
> effect subfiles (by disabling clipping in them as well). Some more:
>
> 4 NOCLIP
> 4 This option disables the clip-mode in the current file.
How about:
11 This option disables clipping for following statements, until a CLIP
11 statement is encountered, or to the end of the current file.
> And:
>
> 10 If neither the CLIP nor NOCLIP option is specified in a file's leading 0 BFC
> 10 statement, then the local clip-state is set to enabled (CLIP) for that file.
See below for my suggestion on this.
> Right under the descriptions of CW and CCW, it explicitely states that you
> can change the winding as many times as you want, but that it isn't
> recommended. Nowhere that I could see does it say anything similar about
> the clip state. The presense of such a statement about winding and lack of
> similar about clipping further implies that clipping is file-wide.
Good point. How about:
4 CLIP
4 This option sets the clip-mode to enabled. This allows clipping, if all
other
4 conditions for clipping are met.
4
4 NOCLIP
4 This option disables the clip-mode in the current file.
4
11 There may be any number of changes to the clip-state in a file, although
it is
11 recommended that such changes be kept to a minimum.
11
10 If neither the CLIP nor NOCLIP option is specified in a file's leading 0
BFC
11 statement, then that file's local clip-state is initially set to enabled
11 (CLIP).
or:
...
11 statement, then the rendering program should treat that file as if it
had the
11 CLIP option set at the start of the file.
> Please let me know if you'd like me to incorporate my suggested changes in
> and post the result for discussion.
That would be great. If you could preserve the format of the document (and
change the rev to 11), I'd appreciate it.
If anyone has a suggestion for a better way to track changes to the
document, I'm open. My main requirement is that no proprietary file
formats (MS Word document, PDF) are allowed.
Steve
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Message has 1 Reply:
 | | Re: Latest BFC Spec?
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| (...) OK, I'll start working on it. It might take a few days. Before I start, though I'd like to suggest resetting all line-version tags in the current version to 1, and then making my new changes as version 2. Given how long it's been since the (...) (22 years ago, 22-Mar-03, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: Latest BFC Spec?
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| (...) The spec should probably be updated to reflect this, I suppose. Please note that this comment and everything below is meant as constructive criticism. It's not meant as a complaint or a slight. I'd just like to see the spec improved. I'll even (...) (22 years ago, 13-Mar-03, to lugnet.cad.dev)
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