Twist a selected region
The remap converts each pixel inside the radius to polar coordinates, changes its angle, and samples the source through bilinear interpolation. Rotation is strongest at the center and approaches 0 at the radius boundary, which keeps the swirled region continuous with the untouched image around it.
Center X and Center Y position the vortex. Radius is proportional to the shorter image side, so the affected area keeps the same relative size in preview and export.
Rotation and falloff
Large rotation values can wrap fine detail around the center several times. Falloff controls how rapidly that rotation weakens with distance. A low falloff spreads motion across the radius; a high value concentrates it near the center.
Place the center over an eye, flower, wheel, or other circular feature for a contained twist. Move it beyond the subject for a broader wave-like bend.
Example: coffee-cup vortex
A top-down shot of a mug is the classic subject. Put Center X and Center Y on the middle of the liquid, set Radius so the boundary sits inside the rim, and use Rotation around 240 with Falloff near 2. The crema streaks become the spiral arms while the cup and table stay perfectly still, and the untouched rim hides the seam.
The same recipe works for anything round: clock faces, records, flowers, and stairwells shot from above.
Small distortions as correction
At low values the swirl doubles as a subtle retouch tool. A rotation of 5 to 15 degrees with a wide radius and low falloff can level a slightly tilted element without rotating the whole frame, since the effect blends back into the surrounding pixels at the boundary. Check straight lines near the radius edge afterward; they show any leftover bend first.