The Skin Filter

The Skin filter applies a reusable drawing to selected nodes or segments. It can put a serif at a corner, fit a terminal across an edge, replace a segment with a more elaborate shape, or repeat a small motif along a path. The source drawing stays in a named glyph, where one edit can update many uses.

The Skin Filter and Skin Sources

The body glyph contains the nodes and segments receiving the treatment. A skin source glyph supplies the skin content: the contours and attachment information used to generate the detail. A body can be a simple skeleton or an existing outline; choose its nodes according to the kind of skin you want to apply.

Prepare a source

The beginning of the source glyph's name determines its skin type:

Prefix	Attachment
_corner	A detail at one body node
_cap	A detail across the two endpoints of a body segment
_segment	One source fitted along a body segment
_dash	Repeated source tiles along a body segment

Add a descriptive suffix, such as _corner.serif or _dash.dot, to distinguish sources. Keep helper glyphs unencoded and turn off their export when they are only construction material. The prefix selects the skin behavior; encoding and export status are separate glyph settings.

Corner and cap sources need an open contour for their joining geometry. They can also contain closed details. Segment and dash sources can use open contours, closed contours, or both, with different fitting behavior for each.

Named anchors define how the source meets the body. In a skin source glyph, the Add Anchor command can supply the names appropriate to its prefix: origin, right, and left for a corner; node1, node2, left, and right for a cap; and start and end for segment or dash sources. Position the anchors deliberately after adding them.

Prepare the source in the layer intended for the body's working layer. A skin retains a source-layer choice and can fall back to the source glyph's active layer when that layer is absent. For predictable work across masters, provide the corresponding source layers and inspect each master's result instead of relying on that fallback.

Apply and edit a skin

1. Prepare the source glyph, including the contours and anchors its type needs.
2. In the body glyph, select a corner node, or the adjacent nodes bounding the segment to receive the skin.
3. Choose Element > Add Filter > Skin.
4. In Choose Skin Filter Source, use the type buttons to narrow the list and choose the source glyph.
5. Inspect the result, then adjust the skin's alignment, scale, flipping, or fitting controls in the property bar.

When you activate an applied skin, red control points and direction indicators identify its placement, and blue outlines show the generated shape. A corner skin's control belongs to its body node. Segment and dash controls are associated with the end of their body segment; a cap control is associated with its start.

Use the property bar to change the source or settings. Edit the source glyph to change the drawing used by all its skins. Edit the body to change the path or junction receiving that drawing.

The Skin widget shows the selected source glyph and its transformation settings.

The property bar also lets you expand or remove the active skin. Element > Expand Filters resolves the containing filtered construction into contours; Element > Remove Filter removes the construction. Retain a native source version if the library relationship will remain useful.

Reusing an applied skin

Activate the skin you want to reuse and choose Edit > Copy. In the destination drawing, select the intended nodes, or make one target node active, then choose Edit > Paste. FontLab retargets the skin's layer and orientation for eligible targets. Inspect the source-layer choice, joins, and direction after pasting; the copied skin still needs a compatible node or segment arrangement.

The Four Skin Types

Corner, cap, and segment skins can finish the structure of a letter: its serifs, terminals, brackets, and worked edges. Dash skins repeat material along an edge and are particularly useful for decorative patterns.

Corner skin

A corner source such as _corner.serif attaches to one body node. Its origin anchor is placed on that node; if the anchor is absent, the source's coordinate origin supplies the location. The source's open contour joins the incoming and outgoing body segments.

The alignment controls determine how those directions influence placement:

• Left prioritizes the incoming side.
• Right prioritizes the outgoing side.
• Center balances the two sides.
• None keeps the skin's orientation and adjusts the adjoining body segments to meet it.

Keep source and body contour directions consistent when judging those joins. Horizontal flipping exchanges the source's incoming and outgoing ends. Vertical flipping reverses its vertical scale. Width and height controls let you scale the detail independently in the two directions.

The left and right source anchors refine the joins on their respective sides. Their positions relative to origin influence where and how the source meets the body. Extra closed contours in the source travel with the placed detail.

Turn an existing serif into a source

1. Work on a saved copy. Select the serif's contour portion and use Contour > Convert > To New Component to create a source named, for example, _corner.serif.
2. Repair the remaining body contour into the simple corner that should receive the serif. Inspect the gap and join the endpoints appropriately.
3. Open the new source glyph. Keep its joining contour open, and put an origin anchor at the point corresponding to that body corner.
4. Return to the body and remove the ordinary component inserted by the extraction step.
5. Select the repaired corner node and apply Element > Add Filter > Skin, choosing _corner.serif.
6. Adjust alignment and inspect both joins.

The source now serves as a corner skin rather than as a separately positioned component. Apply it at other compatible body nodes and edit the source to refine those serifs together.

Cap skin

A cap spans the endpoints of a body segment. Use a source name such as _cap.slab and position node1 and node2 anchors to identify its attachment span. Without those anchors, the open contour's first and last nodes provide the span.

Fit cap controls fitting to the body segment's length. Turn it on when the cap should stretch to match that span. With it off, the cap is not fitted to the full span in the same way; inspect its natural placement and the resulting joins, especially when source and body lengths differ. Any width or height scaling you apply remains a separate setting.

Caps also offer alignment, flipping, scaling, and left/right join anchors. The defining difference from a corner skin is the attachment to two body endpoints rather than one corner.

Segment skin

A segment source such as _segment.bracket is fitted along one body segment. FontLab rotates, scales, and bends its content to follow the segment. Selecting several adjacent body segments applies the source separately to each.

For an open source contour, the first and last nodes supply the attachment ends. For closed content, start and end anchors define the source span. If those anchors are absent, the left and right sidebearing positions on the baseline provide the span instead. Set the source width deliberately if you use that fallback.

A source containing both open and closed contours uses their respective attachment rules. Check the combined result on a curved segment as well as a straight one: the deformation can make a detail that works on a straight stem unsuitable for a tight curve.

Dash skin

A dash source such as _dash.dot repeats along the segment instead of stretching one instance across its entire length. For closed tiles, the source's advance width supplies the repeat length unless start and end define it. Closed tiles rotate along the path without being bent like a continuous segment skin.

Open tiles use their open-contour span and can be fitted so that consecutive endpoints connect. This is useful for a repeating continuous edge. Mixed sources can combine that connecting open material with closed decorative pieces.

For a dotted line, draw a small closed dot in _dash.dot, set a repeat span wider than the dot, and apply the source to a selected open body segment. Adjust the source's span to change spacing and its drawing to change the dot. Inspect the ends of the segment and any sharp changes in direction, where the distribution may need further design work.

Segment, corner, and cap skins also correspond to construction types used by the .glyphs format. When exchanging a working file, check the resulting construction and anchors after conversion.

Choosing Among the Detail Filters

Choose a Smart Corner when the desired detail can be generated from the existing corner: rounding and ink traps need no separate source drawing.

Choose Glue when you have a particular open contour to fasten to a body. It is a direct way to reuse a drawn serif or terminal, with connection points, following behavior, and optional pins controlling the attachment.

Choose Skin when the detail belongs in a named source library or needs a specific node, segment, cap, or repeating attachment model. A corner skin and Glue can both reuse a serif, but the corner skin organizes that reuse around source glyphs and node-level alignment; Glue organizes it around participating elements and their connections.

For repeated dots or an elaborate edge fitted along a curve, the segment and dash skin types provide a more appropriate starting point than a series of manually positioned copies.