def smooth_tris(tris):
"Compute normals at each vertex from a list of triangles"
from TupleMath import minus,cross,normalize
norms = {}
for pt0,pt1,pt2 in tris:
n = normalize(cross(minus(pt1,pt0),minus(pt2,pt0)))
# This is a bad idea, since I'm keying a dictionary on floats!
addappend(norms,fixkey(pt0),n)
addappend(norms,fixkey(pt1),n)
addappend(norms,fixkey(pt2),n)
newtris = []
for pt0,pt1,pt2 in tris:
newtris.append((pt0,average(norms[fixkey(pt0)]),
pt1,average(norms[fixkey(pt1)]),
pt2,average(norms[fixkey(pt2)])))
return newtris
def average(l):
from TupleMath import normalize,plus
avg = (0.,0.,0.)
for xyz in l: avg = plus(avg,xyz)
return normalize(avg)
