]> git.tdb.fi Git - libs/gl.git/commitdiff
Add a bunch of comments to the Mesh class in the Blender exporter
authorMikko Rasa <tdb@tdb.fi>
Sat, 4 May 2019 20:34:15 +0000 (23:34 +0300)
committerMikko Rasa <tdb@tdb.fi>
Sat, 4 May 2019 20:34:15 +0000 (23:34 +0300)
blender/io_mspgl/mesh.py

index 44fbdcb0115b20368ff6499fb6b0c075def650a2..b58637b7f76bb00515c82f29d211c7a380d51395 100644 (file)
@@ -167,12 +167,17 @@ class Mesh:
                self.tbn_vecs = mesh.tbn_vecs
                self.vertex_groups = mesh.vertex_groups
 
+               # Clone basic data
                self.vertices = [Vertex(v) for v in self.vertices]
+               for v in self.vertices:
+                       v.groups = [VertexGroup(g) for g in v.groups]
+
                self.faces = [Face(f) for f in self.polygons]
                self.edges = [Edge(e) for e in self.edges]
                self.loops = self.loops[:]
-
                self.materials = self.materials[:]
+
+               # Clone only the desired UV layers
                if self.use_uv=='NONE' or not self.uv_layers:
                        self.uv_layers = []
                else:
@@ -182,15 +187,15 @@ class Mesh:
                        if self.use_uv=='UNIT0':
                                self.uv_layers = [self.uv_layers[0]]
 
+                       # Assign texture unit numbers to UV layers that lack one
                        next_unit = max((u.unit+1 for u in self.uv_layers if u.unit is not None), default=0)
                        for u in self.uv_layers:
                                if not u.unit:
                                        u.unit = next_unit
                                        next_unit += 1
 
-               for v in self.vertices:
-                       v.groups = [VertexGroup(g) for g in v.groups]
-
+               # Rewrite links between elements to point to cloned data, or create links
+               # where they don't exist
                edge_map = {e.key: e for e in self.edges}
                for f in self.faces:
                        if len(f.vertices)>4:
@@ -210,6 +215,7 @@ class Mesh:
                        for v in e.vertices:
                                v.edges.append(e)
 
+               # Store loose edges as lines
                if self.use_lines:
                        self.lines = [Line(e) for e in self.edges if not e.faces]
                else:
@@ -229,6 +235,8 @@ class Mesh:
                        if u.name!=other.uv_layers[i].name:
                                raise ValueError("Meshes have incompatible UV layers")
 
+               # Merge materials and form a lookup from source material indices to the
+               # merged material list
                material_map = []
                for m in other.materials:
                        if m in self.materials:
@@ -237,6 +245,8 @@ class Mesh:
                                material_map.append(len(self.materials))
                                self.materials.append(m)
 
+               # Append data and adjust indices where necessary.  Since the data is
+               # spliced from the source mesh, rebuilding references is not necessary.
                for i, u in enumerate(self.uv_layers):
                        u.uvs += other.uv_layers[i].uvs
 
@@ -325,6 +335,8 @@ class Mesh:
                                for i in f.loop_indices:
                                        layer.uvs[i] = uv
 
+               # Form a list of UV layers referenced by materials with the array atlas
+               # property set
                array_uv_layers = [t.uv_layer for m in self.materials if m.array_atlas for t in m.texture_slots if t and t.texture_coords=='UV']
                array_uv_layers = [u for u in self.uv_layers if u.name in array_uv_layers]
 
@@ -340,6 +352,7 @@ class Mesh:
                                        for i in f.loop_indices:
                                                l.uvs[i] = mathutils.Vector((*l.uvs[i], layer))
 
+               # Copy UVs from layers to faces
                for f in self.faces:
                        for u in self.uv_layers:
                                f.uvs.append([u.uvs[i] for i in f.loop_indices])
@@ -347,6 +360,8 @@ class Mesh:
                prog_count = len(self.uv_layers)
                prog_step = 0
 
+               # Split by the UV layer used for TBN vectors first so connectivity
+               # remains intact for TBN vector computation
                tbn_layer_index = -1
                if self.tbn_vecs:
                        uv_names = [u.name for u in self.uv_layers]
@@ -360,6 +375,7 @@ class Mesh:
                                progress.pop_task()
                                prog_step = 2
 
+               # Split by the remaining UV layers
                for i, u in enumerate(self.uv_layers):
                        if i==tbn_layer_index:
                                continue
@@ -369,8 +385,10 @@ class Mesh:
                        progress.pop_task()
                        prog_step += 1
 
+               # Copy UVs from faces to vertices
                for v in self.vertices:
                        if v.faces:
+                               # All faces still connected to the vertex have the same UV value
                                f = v.faces[0]
                                i = f.vertices.index(v)
                                v.uvs = [u[i] for u in f.uvs]
@@ -384,11 +402,13 @@ class Mesh:
                        for f in v.faces:
                                f.flag = False
 
+                       # Find all groups of faces on this vertex
                        groups = []
                        for f in v.faces:
                                if not f.flag:
                                        groups.append(find_group_func(v, f, *args))
 
+                       # Give groups after the first separate copies of the vertex
                        for g in groups[1:]:
                                nv = Vertex(v)
                                nv.index = len(self.vertices)
@@ -400,6 +420,7 @@ class Mesh:
                                                continue
 
                                        if len(e_faces_in_g)<len(e.faces):
+                                               # Create a copy of an edge at the boundary of the group
                                                ne = Edge(e)
                                                ne.index = len(self.edges)
                                                self.edges.append(ne)
@@ -418,6 +439,7 @@ class Mesh:
 
                                        e.key = make_edge_key(e.vertices[0].index, e.vertices[1].index)
 
+                               # Filter out any edges that were removed from the original vertex
                                v.edges = [e for e in v.edges if v in e.vertices]
 
                                for f in g:
@@ -466,6 +488,9 @@ class Mesh:
                                edge1 = fv[1].co-fv[0].co
                                edge2 = fv[-1].co-fv[0].co
                                if edge1.length and edge2.length:
+                                       # Use the angle between edges as a weighting factor.  This gives
+                                       # more consistent normals on bends with an inequal number of
+                                       # faces on each side.
                                        v.normal += f.normal*edge1.angle(edge2)
 
                        if v.normal.length:
@@ -476,6 +501,8 @@ class Mesh:
                        progress.set_progress(i/len(self.vertices))
 
        def compute_tbn(self, index, progress):
+               # This function is called at an early stage during UV preparation when
+               # face UVs are not available yet
                layer_uvs = self.uv_layers[index].uvs
 
                for i, v in enumerate(self.vertices):
@@ -609,6 +636,8 @@ def create_mesh_from_object(context, obj, progress):
        progress.set_task("Preparing UVs", 0.7, 1.0)
        mesh.prepare_uv(obj, progress)
 
+       # Discard the temporary Blender meshes after making sure there's no
+       # references to the data
        mesh.drop_references()
        for m in bmeshes:
                bpy.data.meshes.remove(m)