Path: chuka.playstation.co.uk!news
From: "Jon Prestidge (alias Moose)" <zmoose@premier.co.uk>
Newsgroups: scee.yaroze.programming.3d_graphics
Subject: TMD F_4s --some info on setting them up
Date: 3 Jul 1997 11:45:55 GMT
Organization: PlayStation Net Yaroze (SCEE)
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Here's an extract from mail between Mark Theyer and myself that may be of
help to anyone trying to set-up TMD F_4 primitives on-the-fly in their
program(s)....



> From: Mark Theyer <markt@mincom.com>
> To: Jon Prestidge <zmoose@premier.co.uk>
> Subject: Re: TMD mayhem
> Date: 03 July 1997 15:37
> 
> On Jul 2,  7:04pm, Jon Prestidge wrote:
> > Subject: TMD mayhem
> > Hello Mark,
> 
> Hi Jon!
> 
> >    I note you were having problems in defining TMD data on the fly a
while
> > back (from looking at the news-group).    Thanks to the info they gave
out
> > to your problem on creating F_3 types I was able to created those with
no
> > problems.   That was some weeks ago however and I've been trying ever
since
> > to define a F_4 or and F_4G but can't get them to work!  I've more-or
less
> > given-up now and will just be content with making quadrangles with two
> > triangles instead!
> >
> > I'd be interested in knowing if you have tried to define any of the
> > quadragle types and if you were successful.
> >
> > With the F_4 type, no matter what I tried I got a quadrangle shape with
a
> > "V"-shape missing out of it ... which is just madness because it has
five
> > sides like that.   I've not been able to get the F_4G to work at all.
> 
> The "V" shape missing is 'cause your vertex order is wrong (I did it
> also).
> 
> Your vertex data should be in a zigzag direction rather that a square
> definition as per example...
> 
> incorrect:
> 
> v1 ------- v4
>    |     |
>    |     |
> v2 ------- v3
> 
> correct:
> 
> v1 ------- v3
>    |     |
>    |     |
> v2 ------- v4
> 
> I've also worked out how to create double sided versions of quads. Note
> the double sided bit in the primitive header does not work/is not
> supported (Thanks Sony for the doco' on that limitation NOT).
> 
> When you create your quad create a second primitive the same and swap
around
> the vertex index for v2 and v3 (I think - no code in front of me) and
also
> for the texture x,y 2 and 3. This will display a flag, for example, with
> the texture correctly represented and you can see it from any direction.
> Note the vertex data does not need to be copied as you are just changing
> the indexes in the copied primitve.
> 
> I have created flat and flat textured quads so far. Yet to do a gouraud
> quad.
> 
> Hope this helps... by the way, maybe you could forward this to the
> newsgroup (I don't have access) so others who may be having problems
> can read this. I have to use http to access the news - yuk (no subjects,
> just numbers to pick).
> 
>