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).

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).
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.

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.

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.

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 loop from the top with the new values, so you watch the change play out from the beginning each time you tweak.