Geometry
The figure is one parametric curve drawn for t in [−c, c], then rotated four times by 90° to form a symmetric rosette.
x(t) = a · cos(b·t) · sin(b·t) / (1 + 2cos²(d·t))
y(t) = a · sin(b·t) / (1 + sin²(d·t))
Colour encodes distance from the origin: warm and bright at the centre, cooling and dimming toward the rim. Animate sweeps dddd up and down around its current value.