[PD] Vertex transformations

[Stefan Turner]

Chris,

Thanks for the reply. If it's of any use, an idea I
had for transforming vertex positions and colours is
just something like:

[gemhead]
 |
 | [1.2\ [3.4\
 |  |     |
[transform-vertex $fx $fy+$f1 $fz*$f2]
 |
[model whatever.obj]

where 'transform-vertex' takes any number of floats
referenced $f1, $f2...etc (like expr: apologies if I
got the syntax wrong, I don't have pd on this
computer) and has $fx,$fy,$fz for the current vertex
coords. The example above would therefore shift by 1.2
in the y axis and scale by 3.4 in the z axis. A
similar thing could be done with colours. I think even
though this is quite simple it would do for many
applications.

This could be more useful in conjunction with a
'gem-moses' which would act as two 'separators', the
relevant one being chosen depending upon the vertex
position, or something along these lines. (I am not
sure if this would work as I know nothing about how
Gem builds the rendering network etc.)

I would try to code these myself but I don't think I
am up to doing externals yet... Anyway these are just 
ideas and I'm sure you have something similar going
on. Good luck and make sure you tell us all when
you've got something!

Cheers
Stefan.

 --- chris clepper <cgc at humboldtblvd.com> wrote: > On
Mar 30, 2004, at 8:36 AM, Stefan Turner wrote:
> 
> > Hey,
> >
> > Any chance of some more info on how this might
> work?
> > Would there be a new object to apply any
> > transformation to vertex positions and colours, or
> > would it be based on getting and setting arrays? I
> > think both could be quite useful, with the
> > 'transform-vertex' (or whatever) object being
> > (presumably) more efficient and ok for simpler
> stuff,
> > and arrays for anything more complicated.
> 
> Nothing about vertex arrays is set at this point. 
> Right now it's just 
> a collection of objects on my HD that I'm trying to
> make into a 
> coherent set of tools for 'dynamic geometry'.  The
> current idea is to 
> have a set of vertex generators like a grid or a
> .obj model loader and 
> a set of vertex manipulators for color, position and
> so on.  The idea 
> is to process vertex, color, normal and texture
> coordinate data just 
> like pixels or audio.  Pd/GEM is not a very
> effective environment for 
> representing large data sets to the user, so very
> fine editing of the 
> data might not be all that possible.  The goal is to
> have a way to 
> algorithmically alter geometry over time - think
> about something like 
> newwave or Cyrille's pmpd applied any model you load
> into GEM and you 
> start to get the idea.  There will probably be lots
> and lots of of 
> problems to solve before these objects become all
> that useful.
> 
> > Sorry for all the questions, but this sounds just
> like
> > what GEM is currently lacking (for my needs).
> Sorry if
> > any of this has been answered: I haven't been able
> to
> > find much about it.
> 
> By all means let us know what you find lacking about
> GEM.  The past 
> year has been spent getting 'the basics' on each
> platform up to par and 
> improving performance and stability.  Now it's time
> to get some really 
> interesting things going.
> 
> cgc
> 
> > Cheers,
> > Stefan
> >
>  


	
	
		
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