Re: SVG Reader Feedback

Hey Carlos,

I just looked through your code of the nurbs creation part and it looks fine to me. Do you have any svg file containing some Bezier curves so I can play around with it a bit? The weights do work, you can see which values you need to make the curve look as it should by selecting the 2 upper control points and applying a NurbsSetWeights modifier. To test whether the knot vector matches the one you need (which it should in my eyes) you can use the NurbsEditKnotVector modifier.

Hope that helps you with debugging..

Cheers
Carsten

2008/5/26 Carlos Dominguez <carlosadc@...>:

Hi Bart,

Thanks for the feedback, last week I didn't have much time to work on the project but this week I'll have plenty of time. Actually I just committed a revision where I stopped using my own gprim_factory and use k3d::gprim_factory as you told me (I also noticed the add_polygon had a line missing and I was getting assertion errors but I figured it out) Anyway, I'm going to keep working on it but I have a question about the way NURBS are created in k3d. I suck at explaining things like this so I made a little drawing :-) hehe (which I attached to the email).

To actually import a path from SVG the main problem is to convert the bezier curves from the svg file to k3d NURBS. This shouldn't be a difficult task and I almost have it right, you just need to change the knot, and weight vector accordingly (Figure 1 is how it's supposed to be). The problem is that when I do this in k3d no matter how I change the two middle control point weights, the curve always goes to the top (As shown in figure 2) even when I put a very little weight on them(the middle ones) like 0.01 which would mean that those control points have very little contribution, but in k3d it looks kind of like in figure 3 which made me suspect it is the way it is constructed because as of what I know (please correct me if I'm wrong) the curve should look more or less like figure 4 with that weights. What do you think I should do?  Change the control points accordingly to match the original curve? or should the NURBS construction algorithm change? Thanks in advance!

Bests,
Carlos

On Sun, May 25, 2008 at 4:27 PM, Bart Janssens <bart.janssens@...> wrote:

On Sat, May 17, 2008 at 8:41 PM, Carlos Dominguez <carlosadc@...> wrote:
> I just solved the NURBS-Bezier convertion problem, and changed the functions
> as you told me, I hope I get the curve loading complete by today, I'll let
> you know.

Hi Carlos,

I tried your SVG plugin today, and it works great. I have a minor
concern over the gprim_factory, however. There is already a
gprim_factory in k3dsdk, and in my opinion it would be better to add
to that. I think putting it in the SDK is justified, since it is
already used by at least 3 plugins (obj_import, opencascade and CGAL)
and things were diverging already. Do wait for Tim's opinion on this
as well, though.

As a heads-up for the next steps in your project, I have added a
document_importer to opencascade. It might be useful as an example of
how to import a scene with multiple meshes, covering things like
creating FrozenMeshes to store data, set up MeshInstances, connect
render engines, ...

Cheers,

--
Bart

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