Handles overview

Handles allow users to edit the value attributes directly in the Viewport.

Handles with a model
Handles with a model

The handles are positioned so that they are always visible, whichever camera angle is used.

Handles in multiple camera angles
Handles in multiple camera angles

You can enable or disable the handles in the 3D View toolbar under View settings

View settings
or in Edit > Preferences > Scene. By default handles are enabled when present.

Using Handles

When the mouse cursor is placed over a handle, CityEngine highlights both the attribute in the Inspector and the associated scope in the view.

Handles in the Inspector
Handles in the Inspector

Small handles or handles attached to small parts of the model are sometimes not shown. To show these handles, press the control key.

Handle types

There are several different types of handles for editing different types of attributes, such as linear distances, angles, Boolean switches, multiple choice or colors. They are manipulated by dragging, or clicking, the colored (orange) elements.


Linear handles adjust distance attributes. They are edited by dragging the colored markers. When dragging the handle, the value of the attribute is shown. If the value of the attribute is different to the length of the linear handle, the length of the handle is shown in parenthesis.

Linear handle

Some linear handles can be dragged from either end. These handles have two colored arrows.

Handle with colored arrows



Move handles adjust position or offset attributes. They are similar to linear handles, however the length of the move handles is always constant, and dragging one end also moves the opposite end by the same amount.

Move handles



Rotational handles adjust angle attributes. They are edited by dragging the colored sphere.

Rotational handle



Toggle handles adjust Boolean (on/off) attributes. They are edited by clicking the colored square, or dragging the square up and down.

Toggle handle



Selector handles edit multiple choice values. They are edited by clicking the colored circle, or by dragging in a clockwise or anticlockwise direction around the circle.

Selector handle



Color handles edit color attributes. The are edited by clicking and dragging on the colored triangle. When a drag starts, the hue circle appears. Dragging within (or outside) the hue circle adjusts the hue, while dragging inside the triangle adjusts the saturation and brightness. The selected color is shown by a circle within the triangle. Alternately, clicking the triangle, and dragging to a color si

watch selects that color.

Color handle

The range of handles may be limited by the rule (using @Range and @Enum annotations). In this case the values of the handles are constrained when editing.