Subject:
|
Re: Clipping / CCW / CW / INVERT
|
Newsgroups:
|
lugnet.cad.dev
|
Date:
|
Fri, 8 Oct 1999 16:04:27 GMT
|
Reply-To:
|
Rui.Martins@link!nomorespam!.pt
|
Viewed:
|
579 times
|
| |
|
|
On Fri, 8 Oct 1999, Steve Bliss wrote:
> On Fri, 8 Oct 1999 11:00:25 GMT, Rui Martins <Rui.Martins@link.pt> wrote:
> <SNIP>
>
> > > (Side note: there are not actually any solids in LDraw. Only lines and
> > > polygons).
> >
> > I knew that ! ;)
>
> I don't know if I knew you knew that, but I was almost positive you knew
> that. And I knew most everyone else knew that, but I wasn't sure
> absolutely everyone knew that. ;)
touche'!
> <SNIP>
> > LDraw doesn't, but this specification is for new Programs
> > which are backwards compatible with Ldraw, but with a bunch of new
> > enhancements.
>
> Right. New programs may handle transparency either way, so the extensions
> to the description language shouldn't assume which way to go. Plus, the
> description language usually doesn't know the color/transparency, so we
> can't assign the CLIPPING setting in the language anyway.
Not exactly!
If the color has any transparency, force CLIPPING OFF, irrespective of
what the file TAGS inform.
(SIDE NOTE)
when using the tag
0 CLIPPING ON
you are not informing the program that it MUST do clipping, but instead
you are saying that it SHOULD clip if he know how. That's one of the
reasons why this is compatible with LDRAW (it's a comment!).
> > Check the instructions of any LEGO MODEL and you will see an attempt
> > to represent translucency/transparency, by using dots.
> > If we can actually do transparency, we should to it to every polygon
> > that as transparent/translucid color (maybe these are not the correct
> > terms).
>
> I often feel like I'm trans-lucid.
I warned you! ;)
> <SNIP>
> > Remember that this is what is done in OpenGL, which was well though by
> > Silicon Graphics, after years in the 3D business.
>
> Which is an important point.
Every time I look I like more and more OpenGL. It seams that alomst
though everything in advance (that's experience).
> > To use this features, in a similar way, will simplify the making (or
> > appending) of a program written in OpenGL, and probably D3D (since they
> > use something similar).
>
> True, but the translation is fairly straightforward.
Yes it is, but think of me like a polition. ;)
Enlighten only what is relevant to your cause!
> > > > About the INVERT tag
> > > > <SNIP>
>
> I wrote poorly. I should have said: To allow parts-author to selectively
> turn subfiles inside out.
In a previous mail I have come to the conclusion that INVERT is intented
in a diferent way that I was thinking.
> Without the INVERT flag, the rendering program will examine the transform
> matrix, and if it's been inverted, it will adjust for that inversion,
> turned the carefully-inverted subfile back to the original outward-facing
> orientation.
>
> > Remember that you can invert a file with any combination of 1 or 2
> > coord axis.
>
> (inverting on two axes doesn't invert--it's a rotation of 180-degrees
> around the third axis).
>
> > > <SNIP>
> > what do you mean by hanging references ?
>
> I meant in a file like:
>
> 0 INVERT
> <many lines, quads, and triangles>
> 1 16 ... subfile.dat
You shouldn't do this but its allowed, that is like making a define in C
somewhere that is dificult to track down, but you can use it anywhere.
Rui Martins
|
|
Message has 1 Reply:
Message is in Reply To:
 | | Re: Clipping / CCW / CW / INVERT
|
| (...) No, thank you! (...) I don't know if I knew you knew that, but I was almost positive you knew that. And I knew most everyone else knew that, but I wasn't sure absolutely everyone knew that. ;) (...) Right. New programs may handle transparency (...) (25 years ago, 8-Oct-99, to lugnet.cad.dev)
|
18 Messages in This Thread:
 
  
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
