VRML - Mesh deform performance problem

Author

Mesh deform performance problem

Robert Ludig

2004-09-13, 12:17 pm

In the following example I used C=E9cile Mullers (thanks a lot for the
help) code to deform an ElevationGrid.

http://www.htw-dresden.de/~s9686/bigmeshdeform.wrl

My problem here is that the elevtaiongrid is going to be eytremly large
(here "only" 100x100 but 1000x1000 might be required) and each vertex
is going to be moved up to 200 times

In C=E9cile Mullers code the scripts creates and copies a new complete
MFFloat (the heights of the elevation grid in my example with the size
of 100x100) even is only one vertex is going to be moved. So each time
I move a single vertex there is a lot of processing and copying of a
large amounts of data. Data that actually is not affected.

So I was wondering if there is not a way to acess just one Indexed
Vertex and change that without having to "touch" any other vertex, to
increase performance. Maybe with a IndextedFaceSet insead of an
Elevation grid. Or maybe you have other ideas how to improve
performance.
In all other "APIs" I have used so far (shockwave3d/opengl/directx) I
found ways acess and modify just single vertices, but in vrml I don`t
see a solution in vrml from my current horizon.

Robert Lipman

2004-09-13, 7:18 pm

Robert Ludig wrote:
>
> In the following example I used Cécile Mullers (thanks a lot for the
> help) code to deform an ElevationGrid.
>
> http://www.htw-dresden.de/~s9686/bigmeshdeform.wrl
>
> My problem here is that the elevtaiongrid is going to be eytremly large
> (here "only" 100x100 but 1000x1000 might be required) and each vertex
> is going to be moved up to 200 times
>
> In Cécile Mullers code the scripts creates and copies a new complete
> MFFloat (the heights of the elevation grid in my example with the size
> of 100x100) even is only one vertex is going to be moved. So each time
> I move a single vertex there is a lot of processing and copying of a
> large amounts of data. Data that actually is not affected.
>
> So I was wondering if there is not a way to acess just one Indexed
> Vertex and change that without having to "touch" any other vertex, to
> increase performance. Maybe with a IndextedFaceSet insead of an
> Elevation grid. Or maybe you have other ideas how to improve
> performance.
> In all other "APIs" I have used so far (shockwave3d/opengl/directx) I
> found ways acess and modify just single vertices, but in vrml I don`t
> see a solution in vrml from my current horizon.

You might want to take a look at the VRML at
http://cic.nist.gov/vrml/equip.html Most of the models there use an
ElevationGrid that is deformed by the excavator driving over it and/or
digging in it.

I wrote this a long time ago, but what I'm doing (if I remember
correctly) is the height is stored in a MFFloat in a Script node. The
script updates the elevation according to what that excavator is doing
and routes the height to the ElevationGrid. I'm only updating the
necessary points, but of course the entire array gets routed to the
ElevationGrid.

--
Bob Lipman
http://cic.nist.gov/lipman/

Robert Ludewig

2004-09-15, 7:18 pm

There is a actual copy function in that code for the float array

Joerg Scheurich aka MUFTI

2004-09-15, 7:18 pm

Robert Ludewig <schwertfischtrombose@gmx.de> wrote:
> There is a actual copy function in that code for the float array

To which line of code you are referring to ?
To Cecile Muellers code or code from http://cic.nist.gov/vrml/equip.html ?

so long
MUFTI
--
Wir haben die Welt gesucht, um allen Arbeitsflaeche-Verlag Beduerfnisse
zu treffen.
(aus einem Softwarehandbuch, Stichwort: desktop-publishing)

Joerg Scheurich aka MUFTI

2004-09-19, 4:16 am