Confusing method !

Didier Bur

Hi all,
I've coded a method to test if a Point3d lies within a face. This method returns a wrong result sometimes

class Geom;;Point3d
def on_face?(f)
  points3d=[]
  f.vertices.each { |v| points3d.push(v.position) }
  i = self.project_to_plane f.plane
  if self.on_plane?(f.plane) and i == self and Geom.point_in_polygon_2D(self,points3d,true)
    puts "in !"
    return true
  else
    puts "out !"
    return false
  end
end

As you can see, 3 different tests are made to ensure that the point is on the face and within the boundaries of the face, but this is not working !
Help anyone ?

azuby

The first thing I think about is: Calculations with Float type. Maybe in the background.

azuby

daiku

I needed a "point_on_face" method a while back. I can't remember who gave me this tip, but here it is:

if face.classify_point(pt) >= 1 and face.classify_point(pt) <= 4 then...

Didier Bur

Thanx, interesting !
The doc at classify_point is empty

TIG

Todd Burch did something on it a while ago...

http://www.sketchucation.com/forums/scf/viewtopic.php?f=57&t=2927&p=13928&hilit=face#p13928

Didier Bur

Thanx a bunch TIG