Handles allow you to edit value attributes directly in the Viewport window.

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 on the 3D View toolbar under View settings

View settings
. You can also click Edit > Preferences > Scene. By default, handles are enabled when present.

Using handles

When you hover the mouse pointer over a handle, CityEngine highlights both the attribute in the Inspector window and the associated scope in the view.

Handles in the Inspector window
Handles in the Inspector window

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

Handle types

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


Linear handles adjust distance attributes. To edit them, drag the colored markers. When you drag the handle, the value of the attribute is shown. If the value of the attribute is different from the length of the linear handle, the length of the handle is shown in parentheses.

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. To edit them, drag the colored sphere.

Rotational handle



Toggle handles adjust Boolean (on or off) attributes. To edit them, click the colored square, or drag the square up and down.

Toggle handle



Selector handles edit multiple choice values. To edit them, click the colored circle, or drag in a clockwise or counterclockwise direction around the circle.

Selector handle



Color handles edit color attributes. To edit them, click the colored triangle, and drag in (or outside) the hue circle to adjust the hue. Drag inside the triangle to adjust the saturation and brightness. The selected color is shown by a circle within the triangle. Alternatively, click the triangle and drag to a color swatch to select that color.

Color handle

You can limit the range of handles by the rule (using @Range and @Enum annotations). In this case, the values of the handles are constrained when editing.