From a5cae0eebe445275a5404cc68a98c835dfc5b948 Mon Sep 17 00:00:00 2001
From: Stephen Mardson McQuay <stephen@mardson.com>
Date: Mon, 1 Nov 2010 15:53:37 -0600
Subject: [PATCH] starting to implement 3D test case by brute force, very ugly

---
 interp/grid/gmsh.py | 79 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/interp/grid/gmsh.py b/interp/grid/gmsh.py
index 33f1fcc..83762c3 100644
--- a/interp/grid/gmsh.py
+++ b/interp/grid/gmsh.py
@@ -88,3 +88,82 @@ class gmsh_grid(grid):
   def dump_to_blender_files(self, pfile = '/tmp/points.p', ffile = '/tmp/faces.p'):
     pickle.dump([(p[0], p[1], p[2]) for p in self.verts],   open(pfile, 'w'))
     pickle.dump([f.verts for f in self.faces.itervalues()], open(ffile, 'w'))
+
+class gmsh_grid3D(grid):
+  FOUR_NODE_TET = 4
+
+  def __init__(self, filename):
+    """
+      construct an interp.grid.grid-compliant grid
+      object out of a 3D gmsh file
+    """
+
+    gmsh_file = open(filename, 'r')
+
+
+    gmsh_file.readline() # $MeshFormat
+    format = gmsh_file.readline()
+    gmsh_file.readline() # $EndMeshFormat
+
+    gmsh_file.readline() # $Nodes
+
+    node_count = int(gmsh_file.readline())
+
+    self.verts = np.empty((node_count, 3))
+    self.q     = np.empty(node_count)
+
+    for i in xrange(node_count):
+      cur_line = gmsh_file.readline()
+      (index, x,y,z) = cur_line.split()
+      index = int(index) - 1
+
+      self.verts[i][0] = float(x)
+      self.verts[i][1] = float(y)
+      self.verts[i][2] = float(z)
+      self.q[i] = exact_func(self.verts[i])
+
+
+    grid.__init__(self)
+    self.tree = KDTree(self.verts)
+    gmsh_file.readline() # $EndNodes
+    gmsh_file.readline() # $Elements
+
+    # temporary dict used to compute face connectivity
+    neighbors = {}
+
+    element_count = int(gmsh_file.readline())
+    for i in xrange(element_count):
+      cur_line = gmsh_file.readline()
+      cur_line = cur_line.split()
+      cur_face_index, node_type, rest = (int(cur_line[0]),
+                                         int(cur_line[1]),
+                                         [int(j) for j in  cur_line[2:]])
+
+      if(node_type == gmsh_grid3D.FOUR_NODE_TET):
+        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:
+          self.faces_for_vert[cur_point].append(cur_face)
+
+        cur_face.verts       = points_for_cur_face
+
+        self.faces[cur_face_index] = cur_face
+        edges = [tuple(sorted(i)) for i in combinations(points_for_cur_face, 3)]
+
+        # edge is two verts
+        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:
+        self.faces[v[0]].add_neighbor(self.faces[v[1]])
+        self.faces[v[1]].add_neighbor(self.faces[v[0]])
+
+  def dump_to_blender_files(self, pfile = '/tmp/points.p', ffile = '/tmp/faces.p'):
+    pickle.dump([(p[0], p[1], p[2]) for p in self.verts],   open(pfile, 'w'))
+    pickle.dump([f.verts for f in self.faces.itervalues()], open(ffile, 'w'))