Create intersection.py

src/ifcblender/io_import_scene_ifc/intersection.py

@@ -0,0 +1,103 @@
+import bpy
+import bmesh
+
+def bmesh_copy_from_object(obj, transform=True, triangulate=True, apply_modifiers=False):
+    """
+    Returns a transformed, triangulated copy of the mesh
+    """
+
+    assert(obj.type == 'MESH')
+
+    if apply_modifiers and obj.modifiers:
+        me = obj.to_mesh(bpy.context.scene, True, 'PREVIEW', calc_tessface=False)
+        bm = bmesh.new()
+        bm.from_mesh(me)
+        bpy.data.meshes.remove(me)
+    else:
+        me = obj.data
+        if obj.mode == 'EDIT':
+            bm_orig = bmesh.from_edit_mesh(me)
+            bm = bm_orig.copy()
+        else:
+            bm = bmesh.new()
+            bm.from_mesh(me)
+
+    # Remove custom data layers to save memory
+    for elem in (bm.faces, bm.edges, bm.verts, bm.loops):
+        for layers_name in dir(elem.layers):
+            if not layers_name.startswith("_"):
+                layers = getattr(elem.layers, layers_name)
+                for layer_name, layer in layers.items():
+                    layers.remove(layer)
+
+    if transform:
+        bm.transform(obj.matrix_world)
+
+    if triangulate:
+        bmesh.ops.triangulate(bm, faces=bm.faces)
+
+    return bm
+
+def bmesh_check_intersect_objects(obj, obj2):
+    """
+    Check if any faces intersect with the other object
+
+    returns a boolean
+    """
+    assert(obj != obj2)
+
+    # Triangulate
+    bm = bmesh_copy_from_object(obj, transform=True, triangulate=True)
+    bm2 = bmesh_copy_from_object(obj2, transform=True, triangulate=True)
+
+    # If bm has more edges, use bm2 instead for looping over its edges
+    # (so we cast less rays from the simpler object to the more complex object)
+    if len(bm.edges) > len(bm2.edges):
+        bm2, bm = bm, bm2
+
+    # Create a real mesh (lame!)
+    scene = bpy.context.scene
+    me_tmp = bpy.data.meshes.new(name="~temp~")
+    bm2.to_mesh(me_tmp)
+    bm2.free()
+    obj_tmp = bpy.data.objects.new(name=me_tmp.name, object_data=me_tmp)
+    scene.objects.link(obj_tmp)
+    scene.update()
+    ray_cast = obj_tmp.ray_cast
+
+    intersect = False
+
+    EPS_NORMAL = 0.000001
+    EPS_CENTER = 0.01  # should always be bigger
+
+    #for ed in me_tmp.edges:
+    for ed in bm.edges:
+        v1, v2 = ed.verts
+
+        # setup the edge with an offset
+        co_1 = v1.co.copy()
+        co_2 = v2.co.copy()
+        co_mid = (co_1 + co_2) * 0.5
+        no_mid = (v1.normal + v2.normal).normalized() * EPS_NORMAL
+        co_1 = co_1.lerp(co_mid, EPS_CENTER) + no_mid
+        co_2 = co_2.lerp(co_mid, EPS_CENTER) + no_mid
+
+        co, no, index = ray_cast(co_1, co_2)
+        if index != -1:
+            intersect = True
+            break
+
+    scene.objects.unlink(obj_tmp)
+    bpy.data.objects.remove(obj_tmp)
+    bpy.data.meshes.remove(me_tmp)
+
+    scene.update()
+
+    return intersect
+
+
+obj = bpy.context.object
+obj2 = (ob for ob in bpy.context.selected_objects if ob != obj).__next__()
+intersect = bmesh_check_intersect_objects(obj, obj2)
+
+print("There are%s intersections." % ("" if intersect else " NO"))