Re: [Visualpython-users] Recomputing Faces geometry

[Bruce S. <Bru...@nc...>]

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