Projectile: Drag and the Magnus Force in 3D

A whole volley of balls is launched almost together (a few degrees of azimuthal fan) under gravity, quadratic drag and the spin-dependent Magnus force, integrated with RK4. Each ball carries a different sidespin, swept continuously from strong one way, through zero, to strong the other way (a colour gradient). Because the Magnus force is perpendicular to both velocity and spin, each ball curves out of the launch plane by a different amount, so the volley splays into a three-dimensional ribbon over the ground with per-ball shadows. That lateral spread is intrinsically 3D and cannot be read off a flat plot. The camera is a fixed perspective (constant scale, no auto-zoom); azimuth and height sliders rotate it.