Creating a Gobo Light Filter

To create a gobo light filter, right-click in the GafferThree's Object table and select Add → Gobo Light Filter, or press the B key. A gobo light filter is shown as a square in front of the light it is applied on in the Viewer.

A gobo filter in the Gaffer Object Table, and as a white square when applied on a spot light, in the Viewer.

Applying and Positioning a Gobo Light Filter

Applying a Light Filter to a Light

It also permits decoupling the filter transform from the light source transform, so it becomes possible to move / rotate / scale one without the other. The next section explains how this can be achieved.

Positioning a Gobo Light Filter

Placing a gobo light filter as a child of a light will make the filter always follow the light source.

To position the gobo light filter independently from the light source:

• Make sure that the gobo light filter is not parented to any light in the Gaffer Object Table;
• Apply the filter to the desired light sources using a light filter reference, as explained in the previous section;
• Turn on the Use Filter Coordinate System on in the gobo light filter's Material tab.

The gobo light filter can now be positioned by editing its transform in its Object tab.

Controlling a Gobo Light Filter

Interactively editing Gobo Filter Controls in the Viewer

To enable the Gobo Filter Manipulator, select a gobo light filter in the Scene graph or the Viewer. It will unlock a Manipulators → Gobo Filter menu item in the Viewer. Choose this menu item or press the Tab key to display the gobo filter manipulator.

Displaying the manipulator will also fill the Quick Editor with the gobo filter parameters. The Quick Editor can be displayed by choosing Layout → Show Quick Editor, by pressing the A key, or by dragging the right edge of the Viewer to the left.

The gobo filter manipulator offers controls on the Offset and the Scale parameters. Drag the manipulator arrows to edit offsets. Drag the manipulator boxes to edit scale values. The Offset and the Scale parameters are detailed in the next sections.

The gobo filter manipulator in the Viewer.

Gobo Light Filter Controls

The object tab presents the Gobo's transform. The transform is ignored in the rendered image when Use Filter Coordinate System has been turned off in the Material tab.

The Material tab contains several parameters which are explained in the following sections.