3D and WebGL · 3.2

Rotational twist warp

Rotational distortion like wrung fabric. A towel twisted at both ends.

An angular UV displacement whose strength varies with radius, so the field winds around its centre.

JavaScript is off, so the controls are hidden and the stage below shows a static field instead of the running effect. Every word on this page is still here. Nothing is hidden behind the script.

4 knobs

How it actually works

Put this next to the ripple and the difference is instructive. Same cost, same one line of maths, completely different feel: one oscillates, one winds. The ripple has no centre. This is nothing but a centre.

Rotate the UVs about a centre by an angle proportional to distance from that centre (angle = strength * radius), then sample. Because the rotation grows with radius, the middle stays put and the edges chase it, which is what wrings the field instead of just spinning it.

The knobs, named

Twist strength, centre point, radial falloff, rotation over time. The centre-point knob is the one that makes composition legible: move the axis off-centre and the whole field becomes asymmetric.

Knob	Source	What it teaches
Twist strength	ours	How many radians of twist per unit radius. Negative wrings the other way.
Centre X	ours	The axis. Drag it to a corner and the whole composition reorganises.
Centre Y	ours	The other half of the axis.
Radial falloff	ours	The exponent on radius. At 1 the twist grows linearly; at 3 it is calm in the middle and violent at the rim.

sourced means the source names this parameter. ours means the source names none and the knob is our design against the mechanism. No knob here is invented and passed off as sourced.

Evidence

VERIFIED (rendered) for existence; mechanism INFERRED

grep -oE 'href="/features/[a-z0-9-]+"' on gradientlab.co/features returned 19 unique features including /features/twist-warp. The mechanism is INFERRED and is not upgraded here.

Seen on: gradientlab.co/features/twist-warp (TWIST, "Rotational distortion like wrung fabric").
Dependencies: any shader context
Difficulty: moderate
Performance: As 3.1: one quad, cheap.
Accessibility and the floor: Time uniform freezes under reduced motion; the knobs stay live so the field is still explorable.

Notes

Composability. Twist then ripple is a different image from ripple then twist. Order is a parameter nobody exposes.

The honest note: gradientlab publishes the name and the analogy for this one and nothing else. The WAVE page is the only one whose knobs they name. Every slider above is our design against the mechanism we would actually build, and the index marks it that way rather than dressing it up as their spec.

Sinusoidal ripple warp

Radial bulge and pinch