applyBehaviour(particle, time, index) {
    this.calculate(particle, time, index);
    particle.scale = particle.data.scaleB + (particle.data.scaleA - particle.data.scaleB) * this.energy;

    if (particle.scale < 0.0001) particle.scale = 0;
    particle.radius = particle.data.oldRadius * particle.scale;
  }
Applies the scale behaviour to the particle.
@param {Particle} particle - The particle to apply the behaviour to.
@param {number} time - The current simulation time.
@param {number} index - The index of the particle.