* * signedNorm(p, c, R, phi = 0, period = 0) * * Project the vector from circle center c to point p onto a chosen axis, * then normalize by the circle radius R, and clamp to [-1, 1]. * * Geometric meaning: * s = -1 … the point sits one radius "behind" the center along the axis * s = 0 … the point is exactly on the axis’ origin (the center) * s = +1 … the point sits one radius "ahead" of the center along the axis * Values outside the circle are clamped to the ends. * * Math: * u = [cos(phi), sin(phi)] // unit axis at angle phi * v = [p.x - c.x, p.y - c.y] // vector from center to p * s_raw = (v · u) / R // signed distance in radii * s = clamp(s_raw, -1, 1) * * Params: * p: {x, y} point to measure * c: {x, y} circle center * R: number circle radius (must be > 0) * phi: number axis angle in radians (0 = +X, π/2 = +Y) * period: number OPTIONAL phase/offset for the axis angle (see note) * * Return: * number in [-1, 1] — normalized signed position of p along the axis. * * Notes: * • If you want a time-varying axis, use phi + phase (or phi + ω*t). * Adding period directly to sin() (as in the original) breaks unit length. * • R must be positive; R = 0 will blow up.