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<title>JSDoc: Source: phys2d/constraints/p2friction.js</title>
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<h1 class="page-title">Source: phys2d/constraints/p2friction.js</h1>
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<pre class="prettyprint source"><code>if (typeof define !== "function") {
var define = require("amdefine")(module);
}
define([
"odin/base/class",
"odin/math/mathf",
"odin/math/vec2",
"odin/phys2d/constraints/p2equation"
],
function(Class, Mathf, Vec2, P2Equation) {
"use strict";
/**
* @class P2Friction
* @extends P2Equation
* @brief 2d contact equation
*/
function P2Friction() {
P2Equation.call(this);
/**
* @property Vec2 p
* @memberof P2Friction
*/
this.p = new Vec2;
/**
* @property Vec2 t
* @memberof P2Friction
*/
this.t = new Vec2;
this.ri = new Vec2;
this.rj = new Vec2;
this.rixt = 0;
this.rjxt = 0;
}
Class.extend(P2Friction, P2Equation);
P2Friction.prototype.init = function(h) {
var bi = this.bi,
bj = this.bj,
p = this.p,
px = p.x,
py = p.y,
t = this.t,
tx = t.x,
ty = t.y,
xi = bi.position,
xj = bj.position,
ri = this.ri,
rix = px - xi.x,
riy = py - xi.y,
rj = this.rj,
rjx = px - xj.x,
rjy = py - xj.y,
rixt = rix * ty - riy * tx,
rjxt = rjx * ty - rjy * tx;
ri.x = rix;
ri.y = riy;
rj.x = rjx;
rj.y = rjy;
this.rixt = rixt;
this.rjxt = rjxt;
this.lambda = 0;
this.calculateB(h);
this.calculateC();
};
P2Friction.prototype.calculateB = function(h) {
var bi = this.bi,
bj = this.bj,
t = this.t,
tx = t.x,
ty = t.y,
vi = bi.velocity,
wi = bi.angularVelocity || 0,
fi = bi.force,
ti = bi.torque || 0,
invMi = bi.invMass,
invIi = bi.invInertia || 0,
vj = bj.velocity,
wj = bj.angularVelocity || 0,
fj = bj.force,
tj = bj.torque || 0,
invMj = bj.invMass,
invIj = bj.invInertia || 0,
ri = this.ri,
rix = ri.x,
riy = ri.y,
rj = this.rj,
rjx = rj.x,
rjy = rj.y,
Gq = 0,
GWx = vj.x + (-wj * rjy) - vi.x - (-wi * riy),
GWy = vj.y + (wj * rjx) - vi.y - (wi * rix),
GW = GWx * tx + GWy * ty,
GiMfx = fj.x * invMj + (-tj * invIj * rjy) - fi.x * invMi - (-ti * invIi * riy),
GiMfy = fj.y * invMj + (tj * invIj * rjx) - fi.y * invMi - (ti * invIi * rix),
GiMf = GiMfx * tx + GiMfy * ty;
this.B = -this.a * Gq - this.b * GW - h * GiMf;
};
P2Friction.prototype.calculateC = function() {
var bi = this.bi,
bj = this.bj,
rixt = this.rixt,
rjxt = this.rjxt,
invIi = bi.invInertia || 0,
invIj = bj.invInertia || 0,
C = bi.invMass + bj.invMass + this.eps + invIi * rixt * rixt + invIj * rjxt * rjxt;
this.invC = C === 0 ? 0 : 1 / C;
};
P2Friction.prototype.calculateGWlambda = function() {
var bi = this.bi,
bj = this.bj,
t = this.t,
vlambdai = bi.vlambda,
wlambdai = bi.wlambda || 0,
vlambdaj = bj.vlambda,
wlambdaj = bj.wlambda || 0,
ulambdax = vlambdaj.x - vlambdai.x,
ulambday = vlambdaj.y - vlambdai.y,
GWlambda = ulambdax * t.x + ulambday * t.y;
if (wlambdai !== undefined) GWlambda -= wlambdai * this.rixt;
if (wlambdaj !== undefined) GWlambda += wlambdaj * this.rjxt;
return GWlambda;
};
P2Friction.prototype.addToLambda = function(deltaLambda) {
var bi = this.bi,
bj = this.bj,
t = this.t,
tx = t.x,
ty = t.y,
invMi = bi.invMass,
vlambdai = bi.vlambda,
invMj = bj.invMass,
vlambdaj = bj.vlambda;
vlambdai.x -= deltaLambda * invMi * tx;
vlambdai.y -= deltaLambda * invMi * ty;
vlambdaj.x += deltaLambda * invMj * tx;
vlambdaj.y += deltaLambda * invMj * ty;
if (bi.wlambda !== undefined) bi.wlambda -= deltaLambda * bi.invInertia * this.rixt;
if (bj.wlambda !== undefined) bj.wlambda += deltaLambda * bj.invInertia * this.rjxt;
};
return P2Friction;
}
);
</code></pre>
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