Re: [Visualpython-users] Recomputing Faces geometry

[Jamie R. <jam...@gm...>]

Bruce,
Your suggestion for a quicker way to reset faces objects works great.
Thanks for pointing this out.
It is a significant speedup if recalculating lots of faces objects.

Also, I copied the "try norm" lines right out of faces_heightfield.py
in the examples folder.
Probably should change that as it looks like it is no longer (if it
ever was) needed.

Thanks for you time on this - Jamie Riotto




On Sat, Aug 1, 2009 at 3:09 PM, Bruce Sherwood<Bru...@nc...> wrote:
> It occurred to me to try a different approach to the issue of deleting a
> faces object and recreating it. I would guess that performance ought to
> be significantly better if you simply change the faces.pos array as in
> the following version.
>
> Also note the minor point that it isn't necessary to "try" whether
> norm(v) works and then making v = vector(0,0,0) if it doesn't work. As
> the documentation for vector operations in Visual says, if v is
> vector(0,0,0), as a convenience norm(v) returns vector(0,0,0), just as
> you wanted.
>
> Bruce Sherwood
> -------------------------
>
> from __future__ import division
> from visual import *
>
> newframe = frame
>
> class Object(object):
>
>     def __init__(self, parent=None, frame=None, pos=(0,0,0), axis=(1,0,0),
>                                 color=color.green):
>         self.frame = newframe(frame=frame, pos=pos, axis=axis)
>         self.surface = faces(frame=self.frame)
>         self.color = color
>         self.clearSurface()
>
>     def clearSurface(self):
>         self.surface.pos = []
>         self.vertexList = []
>         self.normalList = []
>         self.colorList = []
>
>     def addTri(self, p1, p2, p3):
>         """Add a triangle to the model"""
>         v1 = vector(p1)
>         v2 = vector(p2)
>         v3 = vector(p3)
>
>         normal = norm( cross(v2-v1, v3-v1) )
>
> ## try is not necessary; norm(vector(0,0,0)) is vector(0,0,0) - see docs
> ##        try:
> ##            normal = norm( cross(v2-v1, v3-v1) )
> ##        except:
> ##            normal = vector(0,0,0)
>
>         self.vertexList = self.vertexList + [v1,v2,v3]
>         self.normalList = self.normalList + [normal,normal,normal]
>         self.colorList =  self.colorList +
> [self.color,self.color,self.color]
>
>     def computeSurface(self):
>         """ Create faces out of vertex, normal and color info"""
>         self.surface.pos = self.vertexList
>         self.surface.normal = self.normalList
>         self.surface.color = self.colorList
> ##        self.surface = faces(frame=self.frame, pos=self.vertexList,
> ##                                      normal=self.normalList,
> ##                                      color=self.colorList)
>
> if __name__ == '__main__':
>     # origin sphere for reference
>     sphere(radius=0.1)
>
>     p1 = (-2, -1, 0)
>     p2 = (-1, 1, 0)
>     p3 = (-2,  1, 0)
>
>
>     p4 = (3, -1, 0)
>     p5 = (5, -1, 0)
>     p6 = (4, 2, 0)
>
>     x=Object()
>     x.addTri(p1,  p2,  p3)
>     x.computeSurface()
>     scene.mouse.getclick()
>
>     print "new surface"
>     x.clearSurface()
>     x.addTri(p4, p5, p6)
>     x.computeSurface()
>     print x.vertexList
>
>
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