]> git.tdb.fi Git - libs/gl.git/blobdiff - blender/io_mspgl/mesh.py
Rewrite triangle strip generation in the Blender exporter
[libs/gl.git] / blender / io_mspgl / mesh.py
index 10c2c21430e997465f1f870820b310ba56d98286..08f0bb4ac814ea196d1411de15720c0ff17eb993 100644 (file)
@@ -225,6 +225,8 @@ class Mesh:
                else:
                        self.lines = []
 
+               self.vertex_sequence = []
+
        def __getattr__(self, attr):
                return getattr(self._mesh, attr)
 
@@ -594,6 +596,141 @@ class Mesh:
 
                        progress.set_progress(i/len(self.vertices))
 
+       def prepare_sequence(self, progress):
+               progress.push_task("Reordering faces", 0.0, 0.5)
+               self.reorder_faces(progress)
+
+               progress.set_task("Building sequence", 0.5, 1.0)
+               sequence = None
+               for i, f in enumerate(self.faces):
+                       if sequence:
+                               if len(sequence)==3:
+                                       # Rotate the first three vertices so that the new face can be added
+                                       if sequence[0] in f.vertices and sequence[1] not in f.vertices:
+                                               sequence.append(sequence[0])
+                                               del sequence[0]
+                                       elif sequence[2] not in f.vertices and sequence[1] in f.vertices:
+                                               sequence.insert(0, sequence[-1])
+                                               del sequence[-1]
+
+                               if sequence[-1] not in f.vertices:
+                                       sequence = None
+                               else:
+                                       to_add = [v for v in f.vertices if v!=sequence[-1] and v!=sequence[-2]]
+                                       if len(to_add)==2:
+                                               if (f.vertices[1]==sequence[-1]) != (len(sequence)%2==1):
+                                                       to_add.reverse()
+                                               sequence.append(sequence[-1])
+                                       sequence += to_add
+
+                       if not sequence:
+                               sequence = f.vertices[:]
+                               self.vertex_sequence.append(sequence)
+
+                       progress.set_progress(i/len(self.faces))
+
+               progress.pop_task()
+
+               self.reorder_vertices()
+
+       def reorder_faces(self, progress):
+               # Tom Forsyth's vertex cache optimization algorithm
+               # http://eelpi.gotdns.org/papers/fast_vert_cache_opt.html
+
+               for f in self.faces:
+                       f.flag = False
+
+               last_triangle_score = 0.75
+               cache_decay_power = 1.5
+               valence_boost_scale = 2.0
+               valence_boost_power = -0.5
+
+               max_cache_size = 32
+               cached_vertices = []
+
+               # Keep track of the score and number of unused faces for each vertex
+               vertex_info = [[0, len(v.faces)] for v in self.vertices]
+               for vi in vertex_info:
+                       vi[0] = valence_boost_scale*(vi[1]**valence_boost_power)
+
+               face = None
+               reordered_faces = []
+
+               n_processed = 0
+               while 1:
+                       if not face:
+                               # Previous iteration gave no candidate for best face (or this is
+                               # the first iteration).  Scan all faces for the highest score.
+                               best_score = 0
+                               for f in self.faces:
+                                       if f.flag:
+                                               continue
+
+                                       score = sum(vertex_info[v.index][0] for v in f.vertices)
+                                       if score>best_score:
+                                               best_score = score
+                                               face = f
+
+                       if not face:
+                               break
+
+                       reordered_faces.append(face)
+                       face.flag = True
+
+                       for v in face.vertices:
+                               vertex_info[v.index][1] -= 1
+
+                               # Shuffle the vertex into the front of the cache
+                               if v in cached_vertices:
+                                       cached_vertices.remove(v)
+                               cached_vertices.insert(0, v)
+
+                       # Update scores for all vertices in the cache
+                       for i, v in enumerate(cached_vertices):
+                               score = 0
+                               if i<3:
+                                       score += last_triangle_score
+                               elif i<max_cache_size:
+                                       score += (1-(i-3)/(max_cache_size-3))**cache_decay_power
+                               if vertex_info[v.index][1]:
+                                       score += valence_boost_scale*(vertex_info[v.index][1]**valence_boost_power)
+                               vertex_info[v.index][0] = score
+
+                       face = None
+                       best_score = 0
+                       for v in cached_vertices:
+                               for f in v.faces:
+                                       if not f.flag:
+                                               score = sum(vertex_info[fv.index][0] for fv in f.vertices)
+                                               if score>best_score:
+                                                       best_score = score
+                                                       face = f
+
+                       del cached_vertices[max_cache_size:]
+
+                       n_processed += 1
+                       progress.set_progress(n_processed/len(self.faces))
+
+               self.faces = reordered_faces
+               for i, f in enumerate(self.faces):
+                       f.index = i
+
+       def reorder_vertices(self):
+               for v in self.vertices:
+                       v.index = -1
+
+               reordered_vertices = []
+               for s in self.vertex_sequence:
+                       for v in s:
+                               if v.index<0:
+                                       v.index = len(reordered_vertices)
+                                       reordered_vertices.append(v)
+
+               self.vertices = reordered_vertices
+
+               for e in self.edges:
+                       e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
+
        def drop_references(self):
                for v in self.vertices:
                        v._vertex = None
@@ -607,50 +744,6 @@ class Mesh:
                        u._layer = None
                self._mesh = None
 
-       def create_strip(self, face, max_len):
-               # Find an edge with another unused face next to it
-               edge = None
-               for e in face.edges:
-                       other = e.other_face(face)
-                       if other and not other.flag:
-                               edge = e
-                               break
-
-               if not edge:
-                       return None
-
-               # Add initial vertices so that we'll complete the edge on the first
-               # iteration
-               vertices = face.pivot_vertices(*edge.vertices)
-               if len(vertices)==3:
-                       result = [vertices[-1], vertices[0]]
-               else:
-                       result = [vertices[-2], vertices[-1]]
-
-               while 1:
-                       face.flag = True
-
-                       vertices = face.pivot_vertices(*result[-2:])
-                       k = len(result)%2
-
-                       # Quads need special handling because the winding of every other
-                       # triangle in the strip is reversed
-                       if len(vertices)==4 and not k:
-                               result.append(vertices[3])
-                       result.append(vertices[2])
-                       if len(vertices)==4 and k:
-                               result.append(vertices[3])
-
-                       if len(result)>=max_len:
-                               break
-
-                       # Hop over the last edge
-                       edge = face.get_edge(*result[-2:])
-                       face = edge.other_face(face)
-                       if not face or face.flag:
-                               break
-
-               return result
 
 def create_mesh_from_object(context, obj, progress):
        if obj.type!="MESH":
@@ -693,12 +786,14 @@ def create_mesh_from_object(context, obj, progress):
 
        progress.set_task("Triangulating", 0.2, 0.3)
        mesh.prepare_triangles(progress)
-       progress.set_task("Smoothing", 0.3, 0.6)
+       progress.set_task("Smoothing", 0.3, 0.5)
        mesh.prepare_smoothing(progress)
-       progress.set_task("Vertex groups", 0.6, 0.7)
+       progress.set_task("Vertex groups", 0.5, 0.6)
        mesh.prepare_vertex_groups(obj)
-       progress.set_task("Preparing UVs", 0.7, 1.0)
+       progress.set_task("Preparing UVs", 0.6, 0.8)
        mesh.prepare_uv(obj, progress)
+       progress.set_task("Render sequence", 0.8, 1.0)
+       mesh.prepare_sequence(progress)
 
        # Discard the temporary Blender meshes after making sure there's no
        # references to the data