How to Preserve Sharp Joint Shapes in a Toon Boom Character Rig

Start with one troublesome joint in a duplicate test scene. Compare its original drawing with a bent pose, first with the complete artwork visible and then with the silhouette isolated against a contrasting background. Look for three different problems: a rounded outer corner, an unwanted interior line, or a gap between pieces.

Harmony’s deformation types serve different purposes. Bone deformation creates relatively solid sections with flexible articulations; Curve deformation bends artwork along a Bézier curve and can support a rubber-hose appearance. Envelope deformation surrounds a drawing with editable points and curves. These distinctions explain why changing a limb’s bend may require a different control strategy from changing its outline. How to Use Deformers.

Use this decision aid to choose your first intervention. It is a proposed troubleshooting sequence derived from those tool behaviors, rather than a prescribed Toon Boom setup.

What you see	First intervention	What to inspect next
The outer corner becomes a broad arc	Give the corner a dedicated drawing piece or Envelope point	Whether adjacent edges retain the intended direction
The silhouette is correct but a line crosses the joint	Inspect overlap and patching	Artwork layers and compositing order
Two rigid pieces separate during rotation	Inspect pivot placement and drawing overlap	The tightest required bend
A corner looks correct only on key poses	Inspect intermediate frames	Handle directions, point positions, and corrective keys
Nearby artwork warps with the joint	Inspect hierarchy and influence settings	Which elements should actually deform

Before adding controls, sketch the limb in its straight pose, a moderate bend, and its tightest required bend. Mark the exact point that should form the outside corner in each drawing. This small planning step reveals whether the same piece can supply that corner throughout the movement.

For a graphic design, a useful starting construction is separate upper and lower limb drawings with enough overlap to remain connected. Let one piece supply the visible angular tip, or add a dedicated joint piece when neither segment can maintain the required shape. Treat this as a construction to test: the overlap, corner position, and stacking order depend on your design.

Do not assume that a square joint patch will work at every angle. Rotate the lower segment through the intended range and watch whether the patch becomes a visible block, extends beyond the silhouette, or exposes a seam. If it does, adjust the artwork or reserve a different drawing for that pose.

Keep decoration away from the bend where the design permits it. In his original interview with Cartoon Brew, rigging artist Matt Watts explains that patterns crossing joints and sleeves ending close to an elbow can require additional cutters and deformers. He also recommends building around the poses the animation actually needs. Industry Artist Matt Watts Explains How To Build A Great Rig Using Toon Boom Harmony.

With separate pieces, establish rotation behavior before polishing the seam. A precisely drawn corner cannot compensate for a lower limb rotating around the wrong location.

In Harmony’s Advanced Animation toolbar, select the Rotate tool, select the relevant layer in the Camera or Timeline view, and drag its blue pivot to the intended articulation point. Set pivots for any controlling pegs as well; Toon Boom explicitly notes that added pegs need their own pivot setup. Setting Permanent Pivots.

For this construction, place the lower segment’s pivot at the planned meeting point and test rotation without adding scale or translation. Watch both sides of the joint. If the pieces separate immediately, revisit the pivot and overlap together. If only the outside corner bulges, revise the piece that supplies that corner.

Once the basic rotation works, inspect the tight bend. Leave enough hidden artwork to maintain coverage there, while checking that the extra material does not emerge elsewhere. This establishes a usable range for the rigid construction before you add deformation controls.

An Envelope is useful when the corner must change position or angle between poses. The following starting setup assumes clean vector artwork. Toon Boom notes that default Envelope deformation does not properly handle bitmap images and textures without a weighted deformation setup. Creating Envelope Deformation Rigs.

1. Select the drawing that should deform and choose the Rigging tool from the Deformation toolbar.
2. Enable Envelope mode in Tool Properties and enable automatic grouping.
3. Create the envelope around the drawing, placing a control point at the intended joint corner.
4. Hold Alt while dragging one Bézier handle to rotate it independently of the opposite handle, creating a corner.
5. Adjust the two handles to follow the edges entering and leaving that corner.
6. Close the envelope by holding Alt and clicking its first point. These creation controls are documented in Creating Envelope Deformation Rigs.

For an initial test, use only enough surrounding points to control the adjacent edges. Place neighboring points where you need to preserve the limb’s width or change its direction. Add another point only when you can identify a specific contour problem it will solve.

A corner in the envelope is a control mechanism, so judge the resulting artwork as you pose it. Watch for a narrow spike, a dent beside the tip, or an expanding wedge. Adjust the point position and handle lengths together until the silhouette matches the intended drawing.

Create a short pose test before incorporating the joint into a longer shot. Extend the drawing’s exposure across the test range, establish the first pose with keyframes, choose the Transform tool, and enable Animate Current Frame. Display the selected deformation chain, then add later keyframes and reposition its points and handles. Harmony also permits independent handle rotation during Envelope animation using Alt. Animating Envelope Deformers.

Check which tool is active before editing. Toon Boom distinguishes the Rigging tool’s setup controls from the Transform tool’s animation controls: deformation controls appear red in rigging mode and green in animation mode. Use the animation controls when correcting a pose. How to Use Deformers.

For an illustrative test, key a straight limb on frame 1, a moderate bend on frame 7, and a tight bend on frame 13. Those frame numbers are simply a convenient test arrangement. Scrub every intervening frame and inspect whether the corner travels smoothly and the limb maintains its intended width.

If the corner fails halfway between two good poses, add a corrective pose at the point of failure. Adjust the smallest set of controls that restores the shape, then inspect the frames on both sides. Repeat the test while moving the whole limb so that you can distinguish a local contour problem from a hierarchy problem.

Once the outer shape reads correctly, inspect the interior seam. Auto-Patch can help with compatible artwork: its documented requirements are Pencil outlines in Line Art and painted fills in Colour Art. It extracts and clips the Colour Art so it can cover the appropriate piece. Auto-Patch Node.

When using this method, feed the source drawing through an Auto-Patch node and composite the resulting patch in front of the artwork whose unwanted line needs covering. The official node reference includes a connection example and states that the node requires no parameter adjustment. Follow that example while checking your rig’s stacking order. Auto-Patch Node.

Evaluate the result at both a shallow and a tight bend. A disappearing seam does not establish that the outer corner is correct; return to the silhouette view to verify it. Conversely, a correct corner with an exposed interior line usually calls for an overlap or patch adjustment before another deformation control.

For Brush artwork, inspect your construction before applying the same approach. Toon Boom’s reference describes regular patching as appropriate for brush lines and explains why Pencil fills require Auto-Patch’s clipping behavior. Keep the patching method consistent with the artwork’s structure. Auto-Patch Node.

If a nearby hand, cuff, or other piece distorts while you refine the joint, inspect what sits beneath the deformation chain. Harmony deformers affect artwork through their hierarchy, so selecting the correct layer when creating the chain matters. How to Use Deformers.

For affected artwork, inspect regions of influence in the deformation node’s Layer Properties or the Rigging tool properties. These define the area affected by the deformer. Toon Boom also documents Kinematic Output as a way to prevent a child element from undergoing its parent’s deformation. Game Bone deformers have fixed infinite influence and do not offer adjustable regions. About Regions of Influence.

Finish with a small inspection sheet containing the straight, shallow, moderate, and tight bends, plus any required reverse bend or alternate view. At each pose, check the outer tip, adjacent edge directions, joint width, interior seam, and neighboring artwork. Inspect at the intended display size as well as close up.

Keep the construction that reaches those poses with understandable controls. A rigid overlap may cover most movement, while an Envelope correction handles a few demanding shapes. Record which drawing supplies the corner and where corrections are needed, so the next animation starts from a known, usable setup.

• Harmony 25 Premium Documentation: How to Use Deformers
• Harmony 25 Premium Documentation: Setting Permanent Pivots
• Harmony 25 Premium Documentation: Creating Envelope Deformation Rigs
• Harmony 25 Premium Documentation: Animating Envelope Deformers
• Harmony 25 Premium Documentation: Auto-Patch Node
• Harmony 25 Premium Documentation: About Regions of Influence
• Industry Artist Matt Watts Explains How To Build A Great Rig Using Toon Boom Harmony