Shape geometry tools

You can find additional shape tools under Shapes in the main menu.


The Subdivide tool computes smaller shapes from selected shapes. A variety of parameters can be used to achieve different subdivision layouts.


You can also subdivide shapes formed when creating shapes from graph networks using Block Parameters in the Inspector.

Reverse Normals

This operation reverses the normals, in other words, orientation, of all selected faces. This step is often necessary after importing shapes with reversed orientation.

Separate Faces

You can select a shape or multiple shapes and separate individual shapes for every face. Click Shapes > Separate Faces in the main menu. All new shapes are created in the existing shape layer.

Combine Shapes

You can combine all the faces of the selected shapes into a single shape. Click Shapes > Combine Shapes in the main menu.

Shapes to combine
Shapes to combine are shown.
Multiple shapes combined
Multiple shapes are combined.

Union Shapes

The Union Shapes tool performs a Boolean union of all selected shapes. Select the shapes to be united and click Shapes > Union Shapes in the main menu.

Overlapping shapes.

Shapes overlapped

Selected shapes.

Shapes selected

Multiple shapes united into one shape.

Shape after union

  • The Union Shapes tool is different from the Combine Shapes tool because it creates one face from the outline of the selected overlapping shapes.
  • If the selected shapes are not intersecting or coplanar, the Combine Shapes operation is performed.
  • This tool works only with planar shapes.

Subtract Shapes

The Subtract Shapes tool performs a Boolean subtraction of the lead selection shape from all other selected shapes. Click Shapes > Subtract Shapes in the main menu to subtract the lead selection from the other shape. Press Shift while selecting a different shape to change the lead selection.

Overlapping shapes.

Square and circle shapes

Selected shapes with the circle as lead selection.

Overlapped shapes selected

Square shape after deleting the circle.

Square after deleting circle

This tool works only with planar shapes.

Offset Shapes

The Offset Shapes tool creates a shape, rather than a new face, inside the selected shape or multiple shapes. Select a shape or an individual face and click Shapes > Offset Shapes in the main menu.

Selected shape to create an inside offset.

Shape with offset tool

Offset shape created.

New offset shape created

New offset shape created inside previous offset shape.

Offset shape created

Selected inner offset shape.

Selected inner offset shape.

Offset shape with a hole after deleting the inner shape.

Offset shape with a hole

To manually enter an offset distance, open the Tool Options window Tool options by clicking Window > Tool Options in the CityEngine main menu.

Tool optionsOffset Shapes
Distance (m)

The offset distance in meters. You can enter a value and press Enter to apply.

Remove Holes

Removes all holes from the selected shapes.

Convert Models to Shapes

Use this tool to convert CGA models to shapes for manual editing.

CGA model
A CGA model is shown.
CGA model converted to shape
A CGA model converted to shape.


After this conversion, changes in attributes and CGA rules do not affect the shapes anymore.