initialize(particle) {
    particle.rotation = this.a.getValue();
    particle.data.rotationA = this.a.getValue();

    if (!this.same) particle.data.rotationB = this.b.getValue();
  }
Initializes the behaviour's parameters for a particle.
@param {object} particle - The particle to initialize.
@param {number} particle.rotation - The particle's rotation.
@param {object} particle.data - The particle's data object.