CGTalk - xsi sdk question

M-J

04-07-2003, 09:29 PM

hello everybody,

i recently started an internship (as a programmer) with a german visual effects company and unfortunately i've never programmed in xsi before...so i'm still learning.
on my first day they told to write a tool that makes it possible to copy UV texture coordinates from a polymesh to a surfacemesh. well, first of all i don't have any clue what possible use/advantage this tool could have. but second, which is far more important for me:-): does this work at all??? i mean i checked various internet sites and all i could find was how to copy uvs from one polymesh to another...no mention of surfacemeshes at all. so i'm wondering if this is possible at all!

i hope somebody can help me with that...even if you tell me that it doesn't work.

thanks alot
MJ

Atyss

04-08-2003, 01:16 AM

Hi there,

Congrats for the opportunity, you'll learn a lot.

I'm no programmer, but I can tell you this: it IS possible. In Softimage|3D, the predecessor of XSI, converting a nurbs object to polygons preserved the UV coordinates, wich is not the case with XSI.

Hope this helps
Salutations - Cheers
Bernard Lebel

ThE_JacO

04-08-2003, 01:17 PM

First converting UV from a surface to a mesh is WAY easier then the other way around (that is the case reading the original post), so what SI|3D did is totally different.
Second this kind of copy is quite hard to implement but possible.
Polies rely on a pixel-per-poly mapping when they use UVs (the use of the word UVs when dealing with polies is already arguable by itself), while surfaces will have a width*height distribution of the image flowing accordingly to their isoparms.

Also, while polies are easier to deal with since they can be treated like individual entities, the same isn't true for nurbs, where surfaces are determined by several successive components.

To help you out we'd need a lot more infos.

what kind of models are we looking forward to ?
is alteration of the model to make your life easier contemplated or they must remain untouched ?
what's the pipeline like ?

use of surfaces to model, convert to polies to have an easier life when texturing and then only using the mapping layout on the original surface, is this the workflow model you'll face ? or is it something else I'm missing ?

actually... will the 2 models share at least the same exact topology and vertex numbers ? or we are talking of some normal inspecting inherited mapping or something like that ?

M-J

04-09-2003, 09:12 PM

hey ThE_JacO,

thank you... to know that it works even if it's hard to implement is a little light at the end of the tunnel :-)

but you raised some pretty good questions and the first thing i'm gonna do when i'm back at work tomorrow is to get some answers :-) your idea about converting to polys for easier texturing and then transfering the uvs back to the surface mesh seems quite likely though i don't know yet what this tool will be used for... but i'm gonna find out. i mean, i'd be really glad if you could give me some further advice on this problem...

ciao
MJ

CGTalk Moderation

01-14-2006, 08:00 PM

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.