step method
Implementation
@override
void step(double time, Size size) {
time /= 3;
if (y > 1) {
// Init out of range
y = 0;
t = 0;
}
if (x > 1) x -= 1;
if (x < 0) x += 1;
oldX = x;
oldY = y;
x += (cos(r * t * 3) * sin(r2 * t * 10)) / 3000;
y += time * ys;
t += time;
}