Fix OSM multipolygon buildings

blender/osmassets/building.py

@@ -1,17 +1,130 @@
 """Building feature assembly (`building=*`)."""
 
+import bpy
+from mathutils import Vector
+from mathutils.geometry import tessellate_polygon
+
 from osmassets.mesh import MeshBatch, add_roof, add_wall_panel, make_prism
 from osmassets.osm import parse_height
 
 
-def add_details(name, ring, height, industrial, materials, collection):
-    footprint = ring[:-1] if len(ring) > 1 and ring[0] == ring[-1] else ring
-    if len(footprint) < 3:
+def _open_ring(ring):
+    if len(ring) > 1 and ring[0] == ring[-1]:
+        return ring[:-1]
+    return ring
+
+
+def _valid_rings(outer, inner_rings):
+    rings = [_open_ring(outer)]
+    rings.extend(_open_ring(ring) for ring in (inner_rings or []))
+    return [ring for ring in rings if len(ring) >= 3]
+
+
+def _flat_vertices(rings, z):
+    vertices = []
+    for ring in rings:
+        vertices.extend((x, y, z) for x, y in ring)
+    return vertices
+
+
+def _ring_offsets(rings):
+    offsets = []
+    offset = 0
+    for ring in rings:
+        offsets.append(offset)
+        offset += len(ring)
+    return offsets
+
+
+def _tessellated_faces(rings, offset=0, reverse=False):
+    polygons = [[Vector((x, y, 0.0)) for x, y in ring] for ring in rings]
+    faces = []
+    for triangle in tessellate_polygon(polygons):
+        face = tuple(offset + index for index in triangle)
+        faces.append(tuple(reversed(face)) if reverse else face)
+    return faces
+
+
+def _side_faces(rings, offsets, top_offset):
+    faces = []
+    for ring_index, ring in enumerate(rings):
+        offset = offsets[ring_index]
+        for i in range(len(ring)):
+            j = (i + 1) % len(ring)
+            if ring_index == 0:
+                faces.append((offset + i, offset + j,
+                              top_offset + offset + j, top_offset + offset + i))
+            else:
+                # Inner-ring walls face the courtyard / void, opposite to the
+                # outer shell.
+                faces.append((offset + i, top_offset + offset + i,
+                              top_offset + offset + j, offset + j))
+    return faces
+
+
+def make_prism_with_holes(name, outer, inner_rings, base, height, material, collection):
+    rings = _valid_rings(outer, inner_rings)
+    if not rings:
+        return None
+    if len(rings) == 1:
+        return make_prism(name, rings[0], base, height, material, collection)
+
+    base_vertices = _flat_vertices(rings, base)
+    top_vertices = _flat_vertices(rings, base + height)
+    top_offset = len(base_vertices)
+    offsets = _ring_offsets(rings)
+    faces = []
+    faces.extend(_tessellated_faces(rings, reverse=True))
+    faces.extend(_tessellated_faces(rings, offset=top_offset))
+    faces.extend(_side_faces(rings, offsets, top_offset))
+    mesh = bpy.data.meshes.new(name + "Mesh")
+    mesh.from_pydata(base_vertices + top_vertices, [], faces)
+    mesh.materials.append(material)
+    mesh.update()
+    obj = bpy.data.objects.new(name, mesh)
+    collection.objects.link(obj)
+    return obj
+
+
+def add_roof_with_holes(name, outer, inner_rings, z, material, collection):
+    rings = _valid_rings(outer, inner_rings)
+    if not rings:
+        return None
+    if len(rings) == 1:
+        return add_roof(name, rings[0], z, material, collection)
+
+    mesh = bpy.data.meshes.new(name + "_RoofMesh")
+    mesh.from_pydata(_flat_vertices(rings, z), [], _tessellated_faces(rings))
+    mesh.materials.append(material)
+    mesh.update()
+    obj = bpy.data.objects.new(name + "_Roof", mesh)
+    collection.objects.link(obj)
+    return obj
+
+
+def explicit_height(tag):
+    if "height" not in tag:
+        return None
+    return parse_height(tag, None)
+
+
+def render_height(tag, industrial):
+    explicit = explicit_height(tag)
+    source_height = max(3.0, explicit if explicit is not None else parse_height(tag, 12.0))
+    height = source_height if industrial or explicit is not None or source_height >= 30.0 else 11.4
+    return source_height, height
+
+
+def add_details(name, ring, height, industrial, materials, collection, inner_rings=None):
+    footprints = _valid_rings(ring, inner_rings)
+    if not footprints:
         return
     glass_mat = materials["factory_glass"] if industrial else materials["glass"]
 
     glass_batch = MeshBatch(name + "_Windows", collection, glass_mat)
-    edges = list(zip(footprint, footprint[1:] + footprint[:1]))
+    edges = []
+    for footprint in footprints:
+        edges.extend(zip(footprint, footprint[1:] + footprint[:1]))
     if industrial:
         band_height = min(1.8, max(0.75, height * 0.16))
         band_base = max(0.9, height * 0.52)
@@ -31,15 +144,15 @@ def add_details(name, ring, height, industrial, materials, collection):
     glass_batch.finish()
 
 
-def assemble(ring, way_id, tag, office_overrides, collection, materials):
+def assemble(ring, way_id, tag, office_overrides, collection, materials,
+             inner_rings=None):
     industrial = (tag.get("building") == "industrial" and
                   way_id not in office_overrides)
-    source_height = max(3.0, parse_height(tag, 12.0))
-    height = source_height if industrial or source_height >= 30.0 else 11.4
+    source_height, height = render_height(tag, industrial)
     material = materials["industrial"] if industrial else materials["default"]
     building_name = "Building_" + way_id
-    building_obj = make_prism(building_name, ring, 0.08, height,
-                              material, collection)
+    building_obj = make_prism_with_holes(
+        building_name, ring, inner_rings, 0.08, height, material, collection)
     if building_obj:
         building_obj["osm_height"] = source_height
         building_obj["render_height"] = height
@@ -51,6 +164,8 @@ def assemble(ring, way_id, tag, office_overrides, collection, materials):
         bevel.segments = 2
     roof_mat = (materials["industrial_roof"] if industrial
                 else materials["office_roof"])
-    add_roof(building_name, ring, height + 0.095, roof_mat, collection)
-    add_details(building_name, ring, height, industrial, materials, collection)
+    add_roof_with_holes(building_name, ring, inner_rings, height + 0.095,
+                        roof_mat, collection)
+    add_details(building_name, ring, height, industrial, materials, collection,
+                inner_rings=inner_rings)
     return 1, int(industrial), ring