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