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adds the in_triangle function

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Johann Dreo 2014-05-12 11:37:10 +02:00
commit 646c89d9bb
1 changed files with 22 additions and 0 deletions
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triangulation.py
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@ -97,6 +97,28 @@ def in_circumcircle( p, triangle, epsilon = sys.float_info.epsilon ):
return in_circle( p, (cx,cy), r, epsilon ) return in_circle( p, (cx,cy), r, epsilon )
def in_triangle( p0, triangle, exclude_edges = True ):
"""Return True if the given point lies inside the given triangle"""
p1,p2,p3 = triangle
# Compute the barycentric coordinates
alpha = ( (y(p2) - y(p3)) * (x(p0) - x(p3)) + (x(p3) - x(p2)) * (y(p0) - y(p3)) ) \
/ ( (y(p2) - y(p3)) * (x(p1) - x(p3)) + (x(p3) - x(p2)) * (y(p1) - y(p3)) )
beta = ( (y(p3) - y(p1)) * (x(p0) - x(p3)) + (x(p1) - x(p3)) * (y(p0) - y(p3)) ) \
/ ( (y(p2) - y(p3)) * (x(p1) - x(p3)) + (x(p3) - x(p2)) * (y(p1) - y(p3)) )
gamma = 1.0 - alpha - beta
if exclude_edges:
# If all of alpha, beta, and gamma are strictly greater than 0 and lower than 1,
# (and thus if any of them are lower or equal than 0 or greater than 1)
# then the point p0 strictly lies within the triangle.
return any( x <= 0 or 1 <= x for x in (alpha, beta, gamma ) )
else:
# If the inequality is strict, then the point may lies on an edge.
return any( x < 0 or 1 < x for x in (alpha, beta, gamma ) )
def bounds( vertices ): def bounds( vertices ):
"""Return the iso-axis rectangle enclosing the given points""" """Return the iso-axis rectangle enclosing the given points"""
# find vertices set bounds # find vertices set bounds