Behavior & Tuning

Two tabs shape how the deformation looks and moves: Tuning (the discrete options) and Behavior (the curves that art-direct the motion over time). Applying a preset fills in both; everything below stays editable afterwards.

Tuning

The Tuning tab edits these settings live on the selected actor(s).

Deformation

Setting	What it does
Forward Axis	The local mesh axis that stretches along the spline. Defaults to +X.
Follow Spline Rotation	When on, the surface banks and turns to follow the spline tangent. When off, the mesh keeps its base forward frame.
Preserve Volume	Squashes the perpendicular axes as the mesh stretches, keeping the volume roughly constant (the classic squash-and-stretch trade-off).
Grow Anchor	Where size changes grow from: 0 grows from the center, +1 from the base.
Spline Sample Count	Resolution of the path; higher is smoother along tight curves, at a small memory cost.

Animation

Setting	What it does
Auto Play	Start automatically on BeginPlay.
Loop	Repeat the journey continuously.
Playback Duration	Seconds for one full journey.
Playback Start Delay	Seconds to hold at the start before playing. Group Stagger sets this across a selection.

Behavior curves

The Behavior tab holds the curves that give the motion its character. Each is a collapsible section with an inline draggable mini-curve. They’re seeded with sensible default shapes, so the curve editor is WYSIWYG: what you draw is what plays. Most profiles pair a strength value with a curve over progress; a strength of 0 switches that profile off.

Timing

The timing curve remaps real time to progress along the path:

• X = real time [0..1] → Y = progress.

A straight diagonal (the default) is constant speed. Bend it for ease-in / ease-out, anticipation (dip below zero at the start), or overshoot (rise above one before settling).

Stretch

The cartoon stretch profile along the forward axis:

• Max Stretch Scale: the overall strength.
• Stretch Curve: X = progress [0..1] → Y = stretch alpha, scaled by Max Stretch Scale. The default is a smooth hump peaking mid-journey, so the mesh stretches most while in motion and relaxes at the ends.

Size

Inflate or shrink the mesh as it travels:

• Size Curve: X = progress [0..1] → Y = a direct uniform size multiplier (1 = original size, >1 inflates, <1 shrinks). The default is flat at 1 (no change).
• Size Affects Length: when on, size scales length and girth (a true uniform inflate); when off, only the cross-section girth swells while the length stays put.

Tip

A cleared Size Curve reads as 1, so it can never collapse the mesh to zero; it’s safe to wipe and redraw.

Twist

A roll around the forward axis:

• Max Twist Scale: the roll at full strength.
• Twist Gradient: what rolls. 0 rolls the whole body uniformly; 1 ramps the roll from base to tip, so the mesh wrings like a towel.
• Twist Curve: progress → twist alpha.

Squash

The world-up cartoon squash: stretch tall, then pancake on impact.

• Max Squash/Stretch: the overall strength.
• Squash Anchor: 1 keeps the base planted on the ground while it squashes; 0 squashes about the center.
• Squash Curve: progress → squash alpha. Negative values squash flat, positive values stretch tall.

Because it is always along world up, the squash reads correctly whatever the forward axis is.

Wobble

A lateral jiggle for follow-through and secondary motion:

• Max Wobble: the overall strength.
• Wobble Ramp: how the sway spreads along the body. 0 is uniform; 2 (the default) is a cantilever, where the tip swings much more than the base.
• Wobble Curve: progress → wobble alpha.

Inflate

Puffs every vertex outward along its surface normal, like a balloon or a blowfish. Unlike Size, corners round off.

• Max Inflate and an Inflate Curve (progress → alpha).

Shake

A high-frequency rumble for charge-ups and tension:

• Max Shake: the overall strength.
• Shake Frequency and Shake Speed: how fine and how fast the shudder is.
• Shake Curve: progress → envelope, so the shake can build, hold, and release.

Melt

A world-down sag that pools at the base, for goo, dissolves, and defeats:

• Max Melt: the overall strength.
• Melt Spread: how far the base pools outward.
• Melt Curve: progress → envelope.

Bulge

A localized fattening of the cross-section that can travel along the body, for gulps and swallowing:

• Max Bulge: the overall strength.
• Bulge Width: how long the lump is, as a fraction of the body’s half-length.
• Bulge Curve: progress → envelope (how big the lump is over time).
• Bulge Position: progress → position from base to tip (where the lump is over time).

Assembly

The Behavior tab also hosts the optional Assembly controls (enable toggle, assemble curve, explode radius, tumble, window, lag) for the assembly-along-spline effect. This section is bake-gated: until the mesh is split into pieces it shows only a Bake Pieces… button. See Assembly Along the Spline.

Note

With Live Preview on, every curve edit restarts the preview from the top with the new values, so you watch the change play out from the beginning each time you tweak.