implementing a 2D mesh object for gmsh files

bin/parse_gmsh.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python
+
+import sys
+import pickle
+from pudb import set_trace
+from itertools import combinations
+
+THREE_NODE_TRIANGLE = 2
+
+class point(object):
+  def __init__(self, index, x, y, z):
+    self.index = index
+    self.x     = x
+    self.y     = y
+    self.z     = z
+
+    self.points = []
+    self.faces  = []
+
+  def __getitem__(self, i):
+    if isinstance(i, int):
+      if   i == 0:
+        return self.x
+      elif i == 1:
+        return self.y
+      elif i == 2:
+        return self.z
+      else:
+        raise IndexError("there are only (x,y,z)")
+    elif isinstance(i, str):
+      if i == 'x':
+        return self.x
+      elif i == 'y':
+        return self.y
+      elif i == 'z':
+        return self.z
+      else:
+        raise IndexError
+    else:
+      raise TypeError("only p.x, p[0], and p['x'] access allowed")
+
+  def __str__(self):
+    return '(%f, %f, %f)' % (self.x, self.y, self.z)
+  __repr__ = __str__
+
+class face(object):
+  def __init__(self, index):
+    self.index = index
+    self.neighbors = []
+
+if __name__ == '__main__':
+  if len(sys.argv) != 2:
+    print >> sys.stderr, "usage: %s <gmsh file>" % sys.argv[0]
+    sys.exit(1)
+
+  gmsh_file = open(sys.argv[1], 'r')
+
+
+  gmsh_file.readline() # $MeshFormat
+  format = gmsh_file.readline()
+  gmsh_file.readline() # $EndMeshFormat
+
+  gmsh_file.readline() # $Nodes
+
+  node_count = int(gmsh_file.readline())
+
+  points = []
+  for i in xrange(node_count):
+    cur_line = gmsh_file.readline()
+    (index, x,y,z) = cur_line.split()
+    index = int(index) - 1
+    x     = float(x)
+    y     = float(y)
+    z     = float(z)
+
+    points.append(point(index, x,y,z))
+
+  gmsh_file.readline() # $EndNodes
+  gmsh_file.readline() # $Elements
+
+  element_count = int(gmsh_file.readline())
+
+  faces           = {}
+  faceobjs        = {}
+  faces_for_point = {}
+  neighbors       = {}
+
+  for i in xrange(element_count):
+    cur_line = gmsh_file.readline()
+    cur_line = cur_line.split()
+    cur_face_index, type, rest = (int(cur_line[0]),
+                                  int(cur_line[1]),
+                                  [int(j) for j in  cur_line[2:]])
+
+    if(type == THREE_NODE_TRIANGLE):
+      points_for_cur_face = [i-1 for i in rest[rest[0]+1:]]
+
+      cur_face = face(cur_face_index)
+
+      for cur_point in points_for_cur_face:
+        points[cur_point].faces.append(cur_face_index)
+
+      faces[cur_face_index] = points_for_cur_face
+      cur_face.points       = points_for_cur_face
+
+      faceobjs[cur_face_index] = cur_face
+      edges = [tuple(sorted(i)) for i in combinations(points_for_cur_face, 2)]
+
+      # edge is two points
+      for edge in edges:
+        if edge in neighbors:
+          neighbors[edge].append(cur_face_index)
+        else:
+          neighbors[edge] = [cur_face_index]
+
+  for k,v in neighbors.iteritems():
+    if len(v) > 1:
+      faceobjs[v[0]].neighbors.append(v[1])
+      faceobjs[v[1]].neighbors.append(v[0])
+
+  pickle.dump([(p[0], p[1], p[2]) for p in points], open('/tmp/points.p', 'w'))
+  pickle.dump(faces                               , open('/tmp/faces.p',  'w'))

bin/plot.py

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+from Blender import *
+import bpy
+
+import pickle
+points = pickle.load(open('/tmp/points.p', 'r'))
+faces  = pickle.load(open('/tmp/faces.p', 'r'))
+faces = [faces[i] for i in faces]
+me = bpy.data.meshes.new('points')
+me.verts.extend(points)
+me.faces.extend(faces)
+scn = bpy.data.scenes.active
+ob  = scn.objects.new(me, 'points_obj')