Layered Color Fonts
Layered color fonts are separate fonts that are stacked on top of each other. For such a font to work properly, the software environment in which it is used must support the stacking of text layers.
Initial Setup
Layered color fonts have a color axis. Add it in File → Font Info… → Font by clicking the plus button next to the Axes heading. Name the axis Color and use a four-letter tag such as COLR.
Each color gets its own master.
Contrary to most other fonts, the masters of a layered color font are not interpolated.
This means that the masters of a layered color font are not required to be compatible for interpolation.
Signal this to Glyphs by adding the Enforce Compatibility Check
custom parameter in the Font tab and unchecking it:
With this parameter disabled, add masters for each color layer. Give each master a descriptive name like Front, Inside Light, Inside Shadow, or Outer Shadow. In the Axes Coordinates section, set a different numeric Color value for each master; for example, 1 for the first master and 2 for the second.
Add a Master Color
custom parameter to each master to define its preview color.
Note that custom parameters can also be added when multiple masters are selected.
This color is only used inside Glyphs; the font user can set the exported font files in any color.
Drag the Opacity slider in the color picker to use a semitransparent color for the preview.
Switch to the Exports tab, click the plus button located in the bottom-left and choose Add Instance for each Master. This will add an exporting instance for each axis coordinate of the Color axis.
Editing Color Layers
Edit color layers like normal master layers in Edit View. By default, the currently selected master is shown. Click the eye / buttons in the Layers palette to view multiple layers at the same time. When working with layered color fonts, it is common to show all master layers.
The order of the masters in File → Font Info… → Masters is reflected in Edit View: the first master is shown on top, the second master one layer below, and so on.
Exporting
Layered color fonts are exported as separate font files, one for each color layer. These color layers use the instances as described in Initial Setup.
Glyphs can also convert a layered color font to an SVG color font that includes all color layers in a single font file.
For that, add a new instance in File → Font Info… → Exports and add the Color Layers to SVG
custom parameter.
Then, add the Export SVG Table
custom parameter to the same instance for the SVG data to be included in the export.
Ensure that the checkboxes of both custom parameters are checked.