surfaces/surf/geometry.py
2012-05-07 21:06:39 -06:00

241 lines
6.0 KiB
Python

from __future__ import division
import pprint
'''
http://en.wikipedia.org/wiki/Polygon_mesh
Polygon meshes may be represented in a variety of ways, using different methods
to store the vertex, edge and face data. These include:
- Face-vertex
- Winged-edge
- Half-edge
- Quad-edge
- Corner-tables
- Vertex-vertex
- Face-vertex
We have chosen to use a winged-edge style mesh for our purpopses.
'''
def cross(a, b):
i = a.y * b.z - a.z * b.y
j = a.z * b.x - a.x * b.z
k = a.x * b.y - a.y * b.x
return Vertex(i, j, k)
class Vertex(object):
'''
A vertex is a position along with other information such as color, normal
vector and texture coordinates.
'''
def __init__(self, x=0.0, y=0.0, z=0.0):
'''
'''
self.x = x
self.y = y
self.z = z
def __eq__(self, other):
if(self.x == other.x and self.y == other.y and self.z == other.z):
return True
else:
return False
def __add__(self, other):
# for now just assume type(other) = Vertex... bad, I know
return Vertex(self.x + other.x, self.y + other.y, self.z + other.z)
def __radd__(self, other):
return other + self
def __mul__(self, other):
if isinstance(other, Vertex):
return cross(self, other)
elif isinstance(other, (float, int)):
return Vertex(self.x * other, self.y * other, self.z * other)
else:
raise TypeError("{0} has an unexpected type: {1}".format(
other, type(other)))
def __rmul__(self, other):
return self.__mul__(other)
def __div__(self, other):
# same assumption as __mult__
return Vertex(self.x / other, self.y / other, self.z / other)
__truediv__ = __div__
def __neg__(self):
return Vertex(-self.x, -self.y, -self.z)
def __unicode__(self):
d = {
'id': self.id,
'parent_id': self.parent_id,
'coords': [self.x, self.y, self.z]
}
return pprint.pformat(d)
__str__ = __unicode__
__repr__ = __unicode__
class Edge(object):
'''
'''
next_id = 0
def __init__(self, polygon, parent_id=None, vs=None, es=None, fs=None):
'''
'''
self.polygon = polygon
self.parent_id = parent_id
self.vertex_ids = vs or []
self.edge_ids = es or []
self.face_ids = fs or []
self.id = Edge.next_id
Edge.next_id += 1
def neighbor_face_id(self, neighbor_face_id):
'''Get neighboring face id
'''
if neighbor_face_id == self.face_ids[0]:
return self.face_ids[1]
else:
return self.face_ids[0]
def __unicode__(self):
d = {
'id': self.id,
'vertex_ids': self.vertex_ids,
'edge_ids': self.edge_ids,
'face_ids': self.face_ids,
}
return pprint.pformat(d)
__str__ = __unicode__
__repr__ = __unicode__
@property
def vertices(self):
return [self.polygon.vertex(v_id) for v_id in self.vertex_ids]
@property
def faces(self):
return [self.polygon.face(f_id) for f_id in self.face_ids]
def winged_edges_at_vertex(self, index):
edge_ids = []
for edge in self.edges:
if self.vertex_ids[index] in edge.vertex_ids:
edge_ids.append(edge.id)
return edge_ids
class Face(object):
'''
A face is a closed set of edges,
in which a triangle face has three edges,
and a quad face has four edges.
'''
next_id = 0
def __init__(self, polygon, parent_id=None, es=None):
'''
'''
self.polygon = polygon
self.parent_id = parent_id
self.edge_ids = es or []
self.id = Face.next_id
Face.next_id += 1
def __unicode__(self):
d = {'id': self.id, 'edge_ids': self.edge_ids}
return pprint.pformat(d)
__str__ = __unicode__
__repr__ = __unicode__
def edge(self, edge_id):
return self.polygon.edge(edge_id)
@property
def edges(self):
return [self.polygon.edge(e_id) for e_id in self.edge_ids]
@property
def vertices(self):
vertices = []
for edge_id in self.edge_ids:
edge = self.polygon.edge(edge_id)
vertices.extend(edge.vertices)
return list(set(vertices))
@property
def centroid(self):
'''
'''
# gather all face vertex coords
face_vertices = self.vertices
xs = [vertex.x for vertex in face_vertices]
ys = [vertex.y for vertex in face_vertices]
zs = [vertex.z for vertex in face_vertices]
# average each vertex component
x = sum(xs) / len(xs)
y = sum(ys) / len(ys)
z = sum(zs) / len(zs)
return [x, y, z]
class Polygon(object):
'''
'''
def __init__(self, vs=None, es=None, fs=None):
self.vertices = vs or []
self.edges = es or []
self.faces = fs or []
def face(self, face_id):
for face in self.faces:
if face.id == face_id:
return face
return None
def edge(self, edge_id):
for edge in self.edges:
if edge.id == edge_id:
return edge
return None
def vertex(self, vertex_id):
for vertex in self.vertices:
if vertex.id == vertex_id:
return vertex
return None
def edge_ids_with_parent(self, parent_edge_id):
child_edge_ids = []
for edge in self.edges:
if edge.parent_id == parent_edge_id:
child_edge_ids.append(edge.id)
return child_edge_ids
def __unicode__(self):
d = {
'vertices': self.vertices,
'edges': self.edges,
'faces': self.faces,
}
return pprint.pformat(d)
__str__ = __unicode__
__repr__ = __unicode__