You can now store arbitrary IFC data in the SVG, depending on the drawing style

src/ifcblenderexport/blenderbim/bim/__init__.py

@@ -196,6 +196,8 @@ if bpy is not None:
         operator.SetViewportShadowFromSun,
         operator.SetNorthOffset,
         operator.GetNorthOffset,
+        operator.AddDrawingStyleAttribute,
+        operator.RemoveDrawingStyleAttribute,
         prop.StrProperty,
         prop.Variable,
         prop.Role,

src/ifcblenderexport/blenderbim/bim/cut_ifc.py

@@ -1,4 +1,5 @@
 import os
+import re
 import math
 import time
 import numpy
@@ -807,8 +808,17 @@ class IfcCutter:
         classes = [position, element.is_a()]
         for association in element.HasAssociations:
             if association.is_a('IfcRelAssociatesMaterial'):
-                classes.append('material-{}'.format(self.get_material_name(association.RelatingMaterial)))
+                classes.append('material-{}'.format(
+                    re.sub('[^0-9a-zA-Z]+', '', self.get_material_name(association.RelatingMaterial))
+                ))
         classes.append('globalid-{}'.format(element.GlobalId))
+        for attribute in self.attributes:
+            result = self.selector.get_element_value(element, attribute)
+            if result:
+                classes.append('{}-{}'.format(
+                    re.sub('[^0-9a-zA-Z]+', '', attribute),
+                    re.sub('[^0-9a-zA-Z]+', '', result)
+                ))
         return classes
 
     def get_material_name(self, element):

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -2134,7 +2134,8 @@ class CutSection(bpy.types.Operator):
         import ifccsv
         ifc_cutter.ifc_filenames = [i.name for i in bpy.context.scene.DocProperties.ifc_files]
         ifc_cutter.data_dir = bpy.context.scene.BIMProperties.data_dir
-        ifc_cutter.vector_style = bpy.context.scene.DocProperties.drawing_styles[camera.data.BIMCameraProperties.active_drawing_style_index].vector_style
+        drawing_style = bpy.context.scene.DocProperties.drawing_styles[camera.data.BIMCameraProperties.active_drawing_style_index]
+        ifc_cutter.vector_style = drawing_style.vector_style
         ifc_cutter.diagram_name = self.diagram_name
         ifc_cutter.background_image = bpy.context.scene.render.filepath
         if camera.data.BIMCameraProperties.cut_objects == 'CUSTOM':
@@ -2153,6 +2154,7 @@ class CutSection(bpy.types.Operator):
         ifc_cutter.grid_objs = []
         ifc_cutter.text_objs = []
         ifc_cutter.misc_objs = []
+        ifc_cutter.attributes = [a.name for a in drawing_style.attributes]
         for obj in camera.users_collection[0].objects:
             if 'IfcGrid' in obj.name:
                 ifc_cutter.grid_objs.append(obj)
@@ -3868,3 +3870,24 @@ class GetNorthOffset(bpy.types.Operator):
         bpy.context.scene.MapConversion.x_axis_abscissa = str(cos(x_angle))
         bpy.context.scene.MapConversion.x_axis_ordinate = str(sin(x_angle))
         return {'FINISHED'}
+
+
+class AddDrawingStyleAttribute(bpy.types.Operator):
+    bl_idname = 'bim.add_drawing_style_attribute'
+    bl_label = 'Add Drawing Style Attribute'
+
+    def execute(self, context):
+        props = bpy.context.scene.camera.data.BIMCameraProperties
+        context.scene.DocProperties.drawing_styles[props.active_drawing_style_index].attributes.add()
+        return {'FINISHED'}
+
+
+class RemoveDrawingStyleAttribute(bpy.types.Operator):
+    bl_idname = 'bim.remove_drawing_style_attribute'
+    bl_label = 'Remove Drawing Style Attribute'
+    index: bpy.props.IntProperty()
+
+    def execute(self, context):
+        props = bpy.context.scene.camera.data.BIMCameraProperties
+        context.scene.DocProperties.drawing_styles[props.active_drawing_style_index].attributes.remove(self.index)
+        return {'FINISHED'}

src/ifcblenderexport/blenderbim/bim/prop.py

@@ -521,6 +521,7 @@ class DrawingStyle(PropertyGroup):
     vector_style: EnumProperty(items=getVectorStyles, name='Vector Style')
     include_query: StringProperty(name='Include Query')
     exclude_query: StringProperty(name='Exclude Query')
+    attributes: CollectionProperty(name='Attributes', type=StrProperty)
 
 
 class DocProperties(PropertyGroup):

src/ifcblenderexport/blenderbim/bim/svgwriter.py

@@ -1,4 +1,5 @@
 import os
+import re
 import bpy
 import math
 import pystache
@@ -286,6 +287,44 @@ class SvgWriter():
                 for p in projected_points])
             d = 'M{}'.format(d[1:])
             path = self.svg.add(self.svg.path(d=d, class_=' '.join(classes)))
+
+    def get_attribute_classes(self, obj):
+        classes = []
+        for attribute in self.ifc_cutter.attributes:
+            result = self.get_obj_value(obj, attribute)
+            if result:
+                classes.append('{}-{}'.format(
+                    re.sub('[^0-9a-zA-Z]+', '', attribute),
+                    re.sub('[^0-9a-zA-Z]+', '', result)
+                ))
+        return classes
+
+    def get_obj_value(self, obj, key):
+        # This is a duplicate implementation of the IFC selector key in Blender
+        # In the future if all this becomes purely IFC based this can be deleted
+        if '.' in key \
+                and key.split('.')[0] == 'type':
+            try:
+                obj = obj.BIMObjectProperties.relating_type
+            except:
+                return
+            key = '.'.join(key.split('.')[1:])
+        result = obj.BIMObjectProperties.attributes.get(key)
+        if result:
+            return result.string_value
+        elif key == 'Name':
+            return obj.name.split('/')[1]
+        elif '.' in key:
+            pset_name, prop = key.split('.')
+            pset = obj.BIMObjectProperties.psets.get(pset_name)
+            if not pset:
+                pset = obj.BIMObjectProperties.qtos.get(pset_name)
+            if not pset:
+                return
+            result = pset.properties.get(prop)
+            if result:
+                return result.string_value
+
     def draw_line_annotation(self, obj_data, classes):
         # TODO: properly scope these offsets
         x_offset = self.raw_width / 2
@@ -306,16 +345,22 @@ class SvgWriter():
                 d = 'M{}'.format(d[1:])
                 path = self.svg.add(self.svg.path(d=d, class_=' '.join(classes)))
         elif isinstance(data, bpy.types.Mesh):
-            for edge in data.edges:
-                v0_global = matrix_world @ data.vertices[edge.vertices[0]].co.xyz
-                v1_global = matrix_world @ data.vertices[edge.vertices[1]].co.xyz
-                v0 = self.project_point_onto_camera(v0_global)
-                v1 = self.project_point_onto_camera(v1_global)
-                start = Vector(((x_offset + v0.x), (y_offset - v0.y)))
-                end = Vector(((x_offset + v1.x), (y_offset - v1.y)))
-                vector = end - start
-                line = self.svg.add(self.svg.line(start=tuple(start * self.scale),
-                    end=tuple(end * self.scale), class_=' '.join(classes)))
+            self.draw_edge_annotation(obj, classes)
+
+    def draw_edge_annotation(self, obj, classes):
+        x_offset = self.raw_width / 2
+        y_offset = self.raw_height / 2
+        matrix_world = obj.matrix_world
+        for edge in obj.data.edges:
+            v0_global = matrix_world @ obj.data.vertices[edge.vertices[0]].co.xyz
+            v1_global = matrix_world @ obj.data.vertices[edge.vertices[1]].co.xyz
+            v0 = self.project_point_onto_camera(v0_global)
+            v1 = self.project_point_onto_camera(v1_global)
+            start = Vector(((x_offset + v0.x), (y_offset - v0.y)))
+            end = Vector(((x_offset + v1.x), (y_offset - v1.y)))
+            vector = end - start
+            line = self.svg.add(self.svg.line(start=tuple(start * self.scale),
+                end=tuple(end * self.scale), class_=' '.join(classes)))
 
     def draw_text_annotations(self):
         x_offset = self.raw_width / 2

src/ifcblenderexport/blenderbim/bim/ui.py

@@ -918,6 +918,14 @@ class BIM_PT_camera(Panel):
                 row = layout.row(align=True)
                 row.prop(drawing_style, 'exclude_query')
 
+                row = layout.row()
+                row.operator('bim.add_drawing_style_attribute')
+
+                for index, attribute in enumerate(drawing_style.attributes):
+                    row = layout.row(align=True)
+                    row.prop(attribute, 'name', text='')
+                    row.operator('bim.remove_drawing_style_attribute', icon='X', text='').index = index
+
                 row = layout.row(align=True)
                 row.operator('bim.save_drawing_style')
                 row.operator('bim.activate_drawing_style')