Attributes and Properties Reference

MaStro uses two distinct mechanisms to attach user data to objects:

Mesh attributes — per-element data (vertex, edge, face) stored in mesh.attributes, readable by Geometry Nodes. This is where all parametric data lives.
Custom properties — per-object data stored as Blender custom properties (obj["key"]), defined and managed from the Properties editor. These are not accessible to Geometry Nodes but can be read from Python.

For an explanation of the encoding scheme used for list attributes, see The Attribute System.

Custom Properties (Per-Object)

Custom properties are defined in the Custom Properties sub-panel of the Project Data panel in the Properties editor. Each definition applies to all MaStro objects of the selected type (mass/block, street, or both).

Defining a Custom Property

Click + to add a new entry to the list.
Set Name, Type (Integer, Float, Boolean, or String), default value, and optional constraints (min, max, step, precision).
Choose which object types receive the property via Assign to Mass/Block and Assign to Street.
Click the Assign icon (✓) in the list row to write the property to all existing matching objects. The entry is then locked — type and assignment cannot be changed.
Click Update (↺) to propagate value changes to all objects after editing defaults.

Storage

Each custom property is stored on the object as mastro_custom_{id}, where id is the stable integer ID assigned when the entry is created. The key never changes even if the property is renamed or reordered in the list.

Removing a Custom Property

Click − in the list column next to the entry. If the property has been assigned, a confirmation dialog appears before the key is deleted from all objects and the entry removed from the list.

Viewing and Editing Per-Object Values

In Object Mode, the Custom Properties panel appears in the MaStro sidebar tab when the active object has at least one assigned custom property. Values can be edited directly there.

Mass Attributes (Face Domain)

Stored on faces of Mass objects.

Attribute	Type	Description
`mastro_typology_id`	INT	ID of the assigned typology
`mastro_list_use_id_A`	INT	Tens digits of the use ID list (digit-pair encoded)
`mastro_list_use_id_B`	INT	Units digits of the use ID list (digit-pair encoded)
`mastro_list_storey_A`	INT	Tens digits of the storey count per use (digit-pair encoded)
`mastro_list_storey_B`	INT	Units digits of the storey count per use (digit-pair encoded)
`mastro_list_height_A`	INT	Tens digits of the floor-to-floor height per use
`mastro_list_height_B`	INT	Units digits of the floor-to-floor height per use
`mastro_list_height_C`	INT	First decimal of the floor-to-floor height per use
`mastro_list_height_D`	INT	Second decimal of the floor-to-floor height per use
`mastro_list_height_E`	INT	Third decimal of the floor-to-floor height per use
`mastro_number_of_storeys`	INT	Total number of storeys for this face
`mastro_overlay_top`	INT	Number of top floors to override
`mastro_undercroft`	INT	Number of below-grade floors
`mastro_floor_id`	INT	ID of the assigned floor type
`mastro_custom_face`	FLOAT	Free-form user value per face (see Geometry Data)

Mass Attributes (Edge Domain)

Stored on edges of Mass objects.

Attribute	Type	Description
`mastro_wall_id`	INT	ID of the assigned wall type
`mastro_inverted_normal`	BOOLEAN	Whether the wall normal is flipped
`mastro_custom_edge`	FLOAT	Free-form user value per edge (see Geometry Data)

Mass Attributes (Point Domain)

Stored on vertices of Mass objects.

Attribute	Type	Description
`mastro_custom_vert`	FLOAT	Free-form user value per vertex (see Geometry Data)

Block Attributes (Edge Domain)

Block objects store most attributes on edges with an _EDGE suffix. They mirror the Mass face attributes.

Attribute	Type	Description
`mastro_typology_id_EDGE`	INT	ID of the assigned typology
`mastro_list_use_id_A_EDGE`	INT	Tens digits of the use ID list
`mastro_list_use_id_B_EDGE`	INT	Units digits of the use ID list
`mastro_list_storey_A_EDGE`	INT	Tens digits of the storey count per use
`mastro_list_storey_B_EDGE`	INT	Units digits of the storey count per use
`mastro_list_height_A_EDGE`	INT	Tens digits of the floor-to-floor height per use
`mastro_list_height_B_EDGE`	INT	Units digits of the floor-to-floor height per use
`mastro_list_height_C_EDGE`	INT	First decimal of the floor-to-floor height per use
`mastro_list_height_D_EDGE`	INT	Second decimal of the floor-to-floor height per use
`mastro_list_height_E_EDGE`	INT	Third decimal of the floor-to-floor height per use
`mastro_number_of_storeys_EDGE`	INT	Total number of storeys for this edge
`mastro_overlay_top_EDGE`	INT	Number of top floors to override
`mastro_undercroft_EDGE`	INT	Number of below-grade floors
`mastro_floor_id_EDGE`	INT	ID of the assigned floor type
`mastro_block_depth`	FLOAT	Depth of the building volume from the façade edge
`mastro_inverted_normal_EDGE`	BOOLEAN	Whether the building extrudes in the opposite direction
`mastro_side_angle`	FLOAT	Side rotation angle (stored per vertex)
`mastro_custom_edge`	FLOAT	Free-form user value per edge (see Geometry Data)

Street Attributes (Edge Domain)

Stored on edges of Street objects.

Attribute	Type	Description
`mastro_street_id`	INT	ID of the assigned street type

Drawing Attributes (Edge Domain)

Stored on edges of Drawing Mesh objects. All attributes use the EDGE domain and are created automatically when a drawing object is added.

Attribute	Type	Default	Description
`mastro_drawing_layer`	INT	0	ID of the layer this edge belongs to
`mastro_drawing_thickness`	FLOAT	0.2	Stroke radius in metres (`pen.thickness / 2000`)
`mastro_drawing_style_l1`	FLOAT	1.0	Dash length 1
`mastro_drawing_style_g1`	FLOAT	0.0	Gap after dash 1
`mastro_drawing_style_l2`	FLOAT	0.0	Dash length 2
`mastro_drawing_style_g2`	FLOAT	0.0	Gap after dash 2
`mastro_drawing_style_l3`	FLOAT	0.0	Dash length 3
`mastro_drawing_style_g3`	FLOAT	0.0	Gap after dash 3
`mastro_drawing_visibile`	BOOLEAN	True	Whether this edge produces output
`mastro_drawing_black`	BOOLEAN	False	Marks the edge as a candidate for black-mode rendering
`mastro_drawing_black_switch`	BOOLEAN	False	Set uniformly to True/False by the global Black Mode toggle
`mastro_drawing_resample`	BOOLEAN	True	True when the line style is dashed (any of g1, l2, g2, l3, g3 ≠ 0)

Mesh custom property (on the mesh data-block)

Property	Type	Description
`"MaStro drawing mesh"`	bool	Tags the object as a MaStro Drawing Mesh

CAD Shape Attributes

Added by the CAD tools (Circle, Rectangle, Fillet) when geometry is created inside a Drawing Mesh in Edit Mode. These attributes allow the edit handles to detect and reconstruct shapes for non-destructive editing (Alt+G).

Vertex Domain

Attribute	Type	Description
`mastro_cad_type`	STRING	Shape tag: `"Circle"`, `"Fillet"`, `"Rectangle"`, or `""` (untagged)
`mastro_cad_status`	INT	1 = valid shape, 0 = invalidated (geometry was modified outside the CAD tools)
`mastro_cad_resolution`	INT	Circle/Fillet only: total segment count of the full circle this arc belongs to

Edge Domain

Attribute	Type	Description
`mastro_cad_type_EDGE`	STRING	Same tag as the vertex, mirrored to edges for fast lookup
`mastro_cad_status_EDGE`	INT	Same status as the vertex
`mastro_cad_resolution_EDGE`	INT	Circle/Fillet only: total segment count, mirrored to edges

Notes

All four tag values ("Circle", "Fillet", "Rectangle", "") are defined in CIRCLE_TYPES = {"Circle", "Fillet"} in circle_utils.py; rectangle detection uses "Rectangle".
Setting mastro_cad_status = 0 on any element of a shape de-activates the edit handle for that shape without removing the geometry.
When the CAD tools are used inside a Drawing Mesh, the drawing attributes (mastro_drawing_*) are also written automatically from the currently active drawing layer.

Drawing GP Materials

MaStro creates and manages Grease Pencil materials automatically. These should not be renamed or deleted manually.

Material	Description
`Mastro_GP_{layer_id}`	Per-layer stroke material; colour matches the layer colour
`Mastro_GP_Black`	Solid black material used when Black Mode is active