[Paraview] PolyData bug??

[Moreland, Kenneth]

I understand your sentiments, but the solution is not practical.  If ParaView were primarily used for modeling, which deals with fewer, more complicated elements, then I would totally agree with you.  However, scientific visualization typically deals with data comprising many simple elements.

Checking for convexity is an expensive operation on data that is already tessellated.  This is a problem when using ParaView for large data visualization, which is on of the major things it was designed for.

-Ken

> -----Original Message-----
> From: Alejandro Aragon [mailto:alejandro.aragon at gmail.com]
> Sent: Tuesday, April 01, 2008 9:04 AM
> To: Moreland, Kenneth
> Cc: paraview at paraview.org
> Subject: Re: [Paraview] PolyData bug??
>
> I strongly disagree. The user shouldn't be aware of such a thing. If
> Paraview gives you the option of drawing a polygon, it should be
> independent on its convexity. What it should do, is to check if the
> polygon is convex to use the regular GL function, and if not use
> tessellation to draw it. I have done this myself in the past, so I
> don't think it's a big deal.
>
> aa
>
> On Apr 1, 2008, at 9:06 AM, Moreland, Kenneth wrote:
>
> > I don't think this is a bug.  OpenGL (and every other rendering
> > system that I am aware of) assumes that its polygons are convex.
> > You will have to tessellate your polygons into convex pieces in
> > order for them to be rendered correctly.
> >
> > -Ken
> >
> >> -----Original Message-----
> >> From: paraview-bounces at paraview.org [mailto:paraview-
> bounces at paraview.org
> >> ]
> >> On Behalf Of Alejandro Aragon
> >> Sent: Monday, March 31, 2008 10:31 PM
> >> To: paraview at paraview.org
> >> Subject: [Paraview] PolyData bug??
> >>
> >> Hello everyone,
> >>
> >> I was playing to see if I could write a complicated shape with
> >> PolyData, and I found out that the visualization is really bad. The
> >> surface and surface with edges visualizations don't look quite right.
> >> I attached a wireframe and the surface with edges plots so you can
> >> take a look. Some time back I got the same problem when I tried to
> >> draw a polygon using OpenGL. I was able to solve the problem by using
> >> tesselation, so I believe the same is happening here. I also attached
> >> the vtp file. I'm on Mac OS, but I don't think that would make any
> >> difference.
> >>
> >> Cheers,
> >>
> >> Alejandro Aragón
> >
> >
>