Exporter for Rhinoceros

[Lord Crc]

A few issues:

the shape in the lxs file you attached has the wrong number of knots, however the code you pasted does not. However both miss one "P" point (44, should be nu*nv=5*9=45).

In addition there seems to be a bug in the nurbs code causing an out-of-bounds array access. However since I can't guess the missing "P" I won't be able to see if I have fixed it or not.

[Lord Crc]

It doesn't help that the nurbs code isn't described in the book, other than in the list of supported shapes and parameters

[exvion]

LordCrc, I fixed count points and knots, errors in log disappeared.

patro, How create one nurbs surface in Rhino?

[Lord Crc]

Great! Now I can take a stab at fixing the nurbs code

[Lord Crc]

Right, with the AV fixed I get the same as you.

In order to determine where the issue is it would be preferable if you could output a single nurbs patch similar to what's shown here: http://wiki.blender.org/index.php/File: ... n20-Ex.png It doesn't have to go all the way to the edges (endpoint in blender), just general setup. Then export one with order 2 and order 3, so we can have a closer look

[exvion]

[patro]

exvion, that's awesome

[tomb]

Cool

@exvion: you're probably still at a "play around with it" stage, but do let us know if you think you'll be working on this enough to have a separate forum/mercurial repository!

[patro]

hi,
I hope some one can help me understand..

Luxrender recognize the nurbs geometry....

but what Luxrender finally display in the window is it a rendered nurbs or a mesh?

after parsing the nurbs data does Luxrender mesh the nurbs geometry?

for example exvion had exported a nurbs with 25 knots, the rendered patch have a nice smooth
but if I export similar polygonal surface.. probably I'll get a faceted one! to achieve similar result... I must add an smooth modifier!
this will increase the number of vertex.... that are also to see in the lxs file!

so... what does Luxrender do with the less nurbs data to recognize a so smooth surface?

thanks

Patro

[Lord Crc]

Luxrender recognize the nurbs geometry.... what Luxrender finally display in the window is it a rendered nurbs or a mesh?

Currently it triangulates the nurbs using a fixed number of "steps" in both directions (30, if I read the code right). Considering the complexity of directly rendering a nurbs surface triangulation is probably the best way to go, however a fixed triangulation resolution is non-optimal. It shouldn't be too hard to triangulate based on curvature (and optionally resulting size of the triangles), feel free to add a feature request once the exporter's up and running, so we have something to test with .