[Tioga-users] Fwd: Tioga3d 0.0.1

[Bill Paxton]

I just sent this to Edwin, and then I realized it should probably go  
to the full users list.  It is a comment on the prospects for using  
PDF's ability to do interpolated shading of a triangular mesh -- a  
rather esoteric subject, but one that may turn out to be useful for 3D!

--Bill



Begin forwarded message:

> From: Bill Paxton <paxton at kitp.ucsb.edu>
> Date: June 3, 2006 2:46:42 PM PDT
> To: Edwin <edder at tkwsping.nl>
> Subject: Re: [Tioga-users] Tioga3d 0.0.1
>
>
> On Jun 3, 2006, at 1:29 PM, Edwin wrote:
>
>> First thing I want to do is implement the drawing of a surface  
>> from data points. I have no experience with this type of thing,  
>> but google tells me I should use Delaunay triangulations, if  
>> anyone knows more, please let me know.
>
> Hi Edwin,
>
> Great progress!  I'll download and play with it, but first I wanted  
> to reply to your comment about drawing surfaces.    It sounds like  
> you are on the right track already concerning Delaunay  
> triangulations and qhull, but once you got that working we may want  
> to go one step more and take advantage of the PDF capability for  
> doing Gouraud shaded triangle meshes.   That's something that I  
> skipped on the first round, but it might be worth doing for 3D.    
> In PDF, you can give a triangle mesh with colors at the vertices.   
> The interiors are interpolated (either linear or nonlinear).   The  
> results aren't Pixar quality of course, but they are much nicer  
> than the sharp edges of flat shading.    You should certainly go  
> ahead with flat shading first, but keep in mind the later option of  
> Gouraud.  It will of course mean a shift from treating colors for  
> triangle faces to colors for triangle corners -- but beyond that  
> the main issue will be extending the Tioga PDF code to produce the  
> necessary stuff.    That can't be too hard since the current  
> version of the PDF reference manual is now a mere 1236 pages!   If  
> you don't have a copy, you can get one at http://partners.adobe.com/ 
> public/developer/pdf/index_reference.html#5.  The relevant section  
> starts at page 284.
>
> Cheers,
> Bill
>
>

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