Sha256: cf1dc4f261c2f3be2eef9177106b7c2886d771a709f40ab91db985701b03faf6
Contents?: true
Size: 1.4 KB
Versions: 23
Compression:
Stored size: 1.4 KB
Contents
/**
* Constructs a new drag force with the specified constant.
*
* @class Implements a drag force, simulating friction. The drag force is
* applied in the opposite direction of the particle's velocity. Since Position
* Verlet integration does not track velocities explicitly, the error term with
* this estimate of velocity is fairly high, so the drag force may be
* inaccurate.
*
* @extends pv.Force
* @param {number} k the drag constant.
* @see #constant
*/
pv.Force.drag = function(k) {
var force = {};
if (!arguments.length) k = .1; // default drag constant
/**
* Sets or gets the drag constant, in the range [0,1]. The default drag
* constant is 0.1. The drag forces scales linearly with the particle's
* velocity based on the given drag constant.
*
* @function
* @name pv.Force.drag.prototype.constant
* @param {number} x the new drag constant.
* @returns {pv.Force.drag} this, or the current drag constant.
*/
force.constant = function(x) {
if (arguments.length) { k = x; return force; }
return k;
};
/**
* Applies this force to the specified particles.
*
* @function
* @name pv.Force.drag.prototype.apply
* @param {pv.Particle} particles particles to which to apply this force.
*/
force.apply = function(particles) {
if (k) for (var p = particles; p; p = p.next) {
p.fx -= k * p.vx;
p.fy -= k * p.vy;
}
};
return force;
};
Version data entries
23 entries across 23 versions & 1 rubygems