topical media & game development
#javascript-physics-js-box2d-dynamics-contacts-b2ContactSolver.js / js
/*
* Copyright (c) 2006-2007 Erin Catto
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked, and must not be
* misrepresented the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
var b2ContactSolver = Class.create();
b2ContactSolver.prototype =
{
initialize: function(contacts, contactCount, allocator){
// initialize instance variables for references
this.m_constraints = new Array();
//
this.m_allocator = allocator;
var i = 0;
var tVec;
var tMat;
this.m_constraintCount = 0;
for (i = 0; i < contactCount; ++i)
{
this.m_constraintCount += contacts[i].GetManifoldCount();
}
// fill array
for (i = 0; i < this.m_constraintCount; i++){
this.m_constraints[i] = new b2ContactConstraint();
}
var count = 0;
for (i = 0; i < contactCount; ++i)
{
var contact = contacts[i];
var b1 = contact.m_shape1.m_body;
var b2 = contact.m_shape2.m_body;
var manifoldCount = contact.GetManifoldCount();
var manifolds = contact.GetManifolds();
var friction = contact.m_friction;
var restitution = contact.m_restitution;
//var v1 = b1.m_linearVelocity.Copy();
var v1X = b1.m_linearVelocity.x;
var v1Y = b1.m_linearVelocity.y;
//var v2 = b2.m_linearVelocity.Copy();
var v2X = b2.m_linearVelocity.x;
var v2Y = b2.m_linearVelocity.y;
var w1 = b1.m_angularVelocity;
var w2 = b2.m_angularVelocity;
for (var j = 0; j < manifoldCount; ++j)
{
var manifold = manifolds[ j ];
//b2Settings.b2Assert(manifold.pointCount > 0);
//var normal = manifold.normal.Copy();
var normalX = manifold.normal.x;
var normalY = manifold.normal.y;
//b2Settings.b2Assert(count < this.m_constraintCount);
var c = this.m_constraints[ count ];
c.body1 = b1;
c.body2 = b2;
c.manifold = manifold;
//c.normal = normal;
c.normal.x = normalX;
c.normal.y = normalY;
c.pointCount = manifold.pointCount;
c.friction = friction;
c.restitution = restitution;
for (var k = 0; k < c.pointCount; ++k)
{
var cp = manifold.points[ k ];
var ccp = c.points[ k ];
ccp.normalImpulse = cp.normalImpulse;
ccp.tangentImpulse = cp.tangentImpulse;
ccp.separation = cp.separation;
//var r1 = b2Math.SubtractVV( cp.position, b1.m_position );
var r1X = cp.position.x - b1.m_position.x;
var r1Y = cp.position.y - b1.m_position.y;
//var r2 = b2Math.SubtractVV( cp.position, b2.m_position );
var r2X = cp.position.x - b2.m_position.x;
var r2Y = cp.position.y - b2.m_position.y;
//ccp.localAnchor1 = b2Math.b2MulTMV(b1.m_R, r1);
tVec = ccp.localAnchor1;
tMat = b1.m_R;
tVec.x = r1X * tMat.col1.x + r1Y * tMat.col1.y;
tVec.y = r1X * tMat.col2.x + r1Y * tMat.col2.y;
//ccp.localAnchor2 = b2Math.b2MulTMV(b2.m_R, r2);
tVec = ccp.localAnchor2;
tMat = b2.m_R;
tVec.x = r2X * tMat.col1.x + r2Y * tMat.col1.y;
tVec.y = r2X * tMat.col2.x + r2Y * tMat.col2.y;
var r1Sqr = r1X * r1X + r1Y * r1Y;
var r2Sqr = r2X * r2X + r2Y * r2Y;
//var rn1 = b2Math.b2Dot(r1, normal);
var rn1 = r1X*normalX + r1Y*normalY;
//var rn2 = b2Math.b2Dot(r2, normal);
var rn2 = r2X*normalX + r2Y*normalY;
var kNormal = b1.m_invMass + b2.m_invMass;
kNormal += b1.m_invI * (r1Sqr - rn1 * rn1) + b2.m_invI * (r2Sqr - rn2 * rn2);
//b2Settings.b2Assert(kNormal > Number.MIN_VALUE);
ccp.normalMass = 1.0 / kNormal;
//var tangent = b2Math.b2CrossVF(normal, 1.0);
var tangentX = normalY
var tangentY = -normalX;
//var rt1 = b2Math.b2Dot(r1, tangent);
var rt1 = r1X*tangentX + r1Y*tangentY;
//var rt2 = b2Math.b2Dot(r2, tangent);
var rt2 = r2X*tangentX + r2Y*tangentY;
var kTangent = b1.m_invMass + b2.m_invMass;
kTangent += b1.m_invI * (r1Sqr - rt1 * rt1) + b2.m_invI * (r2Sqr - rt2 * rt2);
//b2Settings.b2Assert(kTangent > Number.MIN_VALUE);
ccp.tangentMass = 1.0 / kTangent;
// Setup a velocity bias for restitution.
ccp.velocityBias = 0.0;
if (ccp.separation > 0.0)
{
ccp.velocityBias = -60.0 * ccp.separation;
}
//var vRel = b2Math.b2Dot(c.normal, b2Math.SubtractVV( b2Math.SubtractVV( b2Math.AddVV( v2, b2Math.b2CrossFV(w2, r2)), v1 ), b2Math.b
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked, and must not be
* misrepresented the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
var b2ContactSolver = Class.create();
b2ContactSolver.prototype =
{
initialize: function(contacts, contactCount, allocator){
// initialize instance variables for references
this.m_constraints = new Array();
//
this.m_allocator = allocator;
var i = 0;
var tVec;
var tMat;
this.m_constraintCount = 0;
for (i = 0; i < contactCount; ++i)
{
this.m_constraintCount += contacts[i].GetManifoldCount();
}
// fill array
for (i = 0; i < this.m_constraintCount; i++){
this.m_constraints[i] = new b2ContactConstraint();
}
var count = 0;
for (i = 0; i < contactCount; ++i)
{
var contact = contacts[i];
var b1 = contact.m_shape1.m_body;
var b2 = contact.m_shape2.m_body;
var manifoldCount = contact.GetManifoldCount();
var manifolds = contact.GetManifolds();
var friction = contact.m_friction;
var restitution = contact.m_restitution;
//var v1 = b1.m_linearVelocity.Copy();
var v1X = b1.m_linearVelocity.x;
var v1Y = b1.m_linearVelocity.y;
//var v2 = b2.m_linearVelocity.Copy();
var v2X = b2.m_linearVelocity.x;
var v2Y = b2.m_linearVelocity.y;
var w1 = b1.m_angularVelocity;
var w2 = b2.m_angularVelocity;
for (var j = 0; j < manifoldCount; ++j)
{
var manifold = manifolds[ j ];
//b2Settings.b2Assert(manifold.pointCount > 0);
//var normal = manifold.normal.Copy();
var normalX = manifold.normal.x;
var normalY = manifold.normal.y;
//b2Settings.b2Assert(count < this.m_constraintCount);
var c = this.m_constraints[ count ];
c.body1 = b1;
c.body2 = b2;
c.manifold = manifold;
//c.normal = normal;
c.normal.x = normalX;
c.normal.y = normalY;
c.pointCount = manifold.pointCount;
c.friction = friction;
c.restitution = restitution;
for (var k = 0; k < c.pointCount; ++k)
{
var cp = manifold.points[ k ];
var ccp = c.points[ k ];
ccp.normalImpulse = cp.normalImpulse;
ccp.tangentImpulse = cp.tangentImpulse;
ccp.separation = cp.separation;
//var r1 = b2Math.SubtractVV( cp.position, b1.m_position );
var r1X = cp.position.x - b1.m_position.x;
var r1Y = cp.position.y - b1.m_position.y;
//var r2 = b2Math.SubtractVV( cp.position, b2.m_position );
var r2X = cp.position.x - b2.m_position.x;
var r2Y = cp.position.y - b2.m_position.y;
//ccp.localAnchor1 = b2Math.b2MulTMV(b1.m_R, r1);
tVec = ccp.localAnchor1;
tMat = b1.m_R;
tVec.x = r1X * tMat.col1.x + r1Y * tMat.col1.y;
tVec.y = r1X * tMat.col2.x + r1Y * tMat.col2.y;
//ccp.localAnchor2 = b2Math.b2MulTMV(b2.m_R, r2);
tVec = ccp.localAnchor2;
tMat = b2.m_R;
tVec.x = r2X * tMat.col1.x + r2Y * tMat.col1.y;
tVec.y = r2X * tMat.col2.x + r2Y * tMat.col2.y;
var r1Sqr = r1X * r1X + r1Y * r1Y;
var r2Sqr = r2X * r2X + r2Y * r2Y;
//var rn1 = b2Math.b2Dot(r1, normal);
var rn1 = r1X*normalX + r1Y*normalY;
//var rn2 = b2Math.b2Dot(r2, normal);
var rn2 = r2X*normalX + r2Y*normalY;
var kNormal = b1.m_invMass + b2.m_invMass;
kNormal += b1.m_invI * (r1Sqr - rn1 * rn1) + b2.m_invI * (r2Sqr - rn2 * rn2);
//b2Settings.b2Assert(kNormal > Number.MIN_VALUE);
ccp.normalMass = 1.0 / kNormal;
//var tangent = b2Math.b2CrossVF(normal, 1.0);
var tangentX = normalY
var tangentY = -normalX;
//var rt1 = b2Math.b2Dot(r1, tangent);
var rt1 = r1X*tangentX + r1Y*tangentY;
//var rt2 = b2Math.b2Dot(r2, tangent);
var rt2 = r2X*tangentX + r2Y*tangentY;
var kTangent = b1.m_invMass + b2.m_invMass;
kTangent += b1.m_invI * (r1Sqr - rt1 * rt1) + b2.m_invI * (r2Sqr - rt2 * rt2);
//b2Settings.b2Assert(kTangent > Number.MIN_VALUE);
ccp.tangentMass = 1.0 / kTangent;
// Setup a velocity bias for restitution.
ccp.velocityBias = 0.0;
if (ccp.separation > 0.0)
{
ccp.velocityBias = -60.0 * ccp.separation;
}
//var vRel = b2Math.b2Dot(c.normal, b2Math.SubtractVV( b2Math.SubtractVV( b2Math.AddVV( v2, b2Math.b2CrossFV(w2, r2)), v1 ), b2Math.b2CrossFV(w1, r1)));
var tX = v2X + (-w2*r2Y) - v1X - (-w1*r1Y);
var tY = v2Y + (w2*r2X) - v1Y - (w1*r1X);
//var vRel = b2Dot(c.normal, tX/Y);
var vRel = c.normal.x*tX + c.normal.y*tY;
if (vRel < -b2Settings.b2_velocityThreshold)
{
ccp.velocityBias += -c.restitution * vRel;
}
}
++count;
}
}
//b2Settings.b2Assert(count == this.m_constraintCount);
},
//~b2ContactSolver();
PreSolve: function(){
var tVec;
var tVec2;
var tMat;
// Warm start.
for (var i = 0; i < this.m_constraintCount; ++i)
{
var c = this.m_constraints[ i ];
var b1 = c.body1;
var b2 = c.body2;
var invMass1 = b1.m_invMass;
var invI1 = b1.m_invI;
var invMass2 = b2.m_invMass;
var invI2 = b2.m_invI;
//var normal = new b2Vec2(c.normal.x, c.normal.y);
var normalX = c.normal.x;
var normalY = c.normal.y;
//var tangent = b2Math.b2CrossVF(normal, 1.0);
var tangentX = normalY;
var tangentY = -normalX;
var j = 0;
var tCount = 0;
if (b2World.s_enableWarmStarting)
{
tCount = c.pointCount;
for (j = 0; j < tCount; ++j)
{
var ccp = c.points[ j ];
//var P = b2Math.AddVV( b2Math.MulFV(ccp.normalImpulse, normal), b2Math.MulFV(ccp.tangentImpulse, tangent));
var PX = ccp.normalImpulse*normalX + ccp.tangentImpulse*tangentX;
var PY = ccp.normalImpulse*normalY + ccp.tangentImpulse*tangentY;
//var r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
tMat = b1.m_R;
tVec = ccp.localAnchor1;
var r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y;
var r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y;
//var r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
tMat = b2.m_R;
tVec = ccp.localAnchor2;
var r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y;
var r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y;
//b1.m_angularVelocity -= invI1 * b2Math.b2CrossVV(r1, P);
b1.m_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);
//b1.m_linearVelocity.Subtract( b2Math.MulFV(invMass1, P) );
b1.m_linearVelocity.x -= invMass1 * PX;
b1.m_linearVelocity.y -= invMass1 * PY;
//b2.m_angularVelocity += invI2 * b2Math.b2CrossVV(r2, P);
b2.m_angularVelocity += invI2 * (r2X * PY - r2Y * PX);
//b2.m_linearVelocity.Add( b2Math.MulFV(invMass2, P) );
b2.m_linearVelocity.x += invMass2 * PX;
b2.m_linearVelocity.y += invMass2 * PY;
ccp.positionImpulse = 0.0;
}
}
else{
tCount = c.pointCount;
for (j = 0; j < tCount; ++j)
{
var ccp2 = c.points[ j ];
ccp2.normalImpulse = 0.0;
ccp2.tangentImpulse = 0.0;
ccp2.positionImpulse = 0.0;
}
}
}
},
SolveVelocityConstraints: function(){
var j = 0;
var ccp;
var r1X;
var r1Y;
var r2X;
var r2Y;
var dvX;
var dvY;
var lambda;
var newImpulse;
var PX;
var PY;
var tMat;
var tVec;
for (var i = 0; i < this.m_constraintCount; ++i)
{
var c = this.m_constraints[ i ];
var b1 = c.body1;
var b2 = c.body2;
var b1_angularVelocity = b1.m_angularVelocity;
var b1_linearVelocity = b1.m_linearVelocity;
var b2_angularVelocity = b2.m_angularVelocity;
var b2_linearVelocity = b2.m_linearVelocity;
var invMass1 = b1.m_invMass;
var invI1 = b1.m_invI;
var invMass2 = b2.m_invMass;
var invI2 = b2.m_invI;
//var normal = new b2Vec2(c.normal.x, c.normal.y);
var normalX = c.normal.x;
var normalY = c.normal.y;
//var tangent = b2Math.b2CrossVF(normal, 1.0);
var tangentX = normalY;
var tangentY = -normalX;
// Solver normal constraints
var tCount = c.pointCount;
for (j = 0; j < tCount; ++j)
{
ccp = c.points[ j ];
//r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
tMat = b1.m_R;
tVec = ccp.localAnchor1;
r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
//r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
tMat = b2.m_R;
tVec = ccp.localAnchor2;
r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
// Relative velocity at contact
//var dv = b2Math.SubtractVV( b2Math.AddVV( b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b2Math.SubtractVV(b1.m_linearVelocity, b2Math.b2CrossFV(b1.m_angularVelocity, r1)));
//dv = b2Math.SubtractVV(b2Math.SubtractVV( b2Math.AddVV( b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);
// Compute normal impulse
//var vn = b2Math.b2Dot(dv, normal);
var vn = dvX * normalX + dvY * normalY;
lambda = -ccp.normalMass * (vn - ccp.velocityBias);
// b2Clamp the accumulated impulse
newImpulse = b2Math.b2Max(ccp.normalImpulse + lambda, 0.0);
lambda = newImpulse - ccp.normalImpulse;
// Apply contact impulse
//P = b2Math.MulFV(lambda, normal);
PX = lambda * normalX;
PY = lambda * normalY;
//b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
b1_linearVelocity.x -= invMass1 * PX;
b1_linearVelocity.y -= invMass1 * PY;
b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);
//b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
b2_linearVelocity.x += invMass2 * PX;
b2_linearVelocity.y += invMass2 * PY;
b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);
ccp.normalImpulse = newImpulse;
// MOVED FROM BELOW
// Relative velocity at contact
//var dv = b2.m_linearVelocity + b2Cross(b2.m_angularVelocity, r2) - b1.m_linearVelocity - b2Cross(b1.m_angularVelocity, r1);
//dv = b2Math.SubtractVV(b2Math.SubtractVV(b2Math.AddVV(b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);
// Compute tangent impulse
var vt = dvX*tangentX + dvY*tangentY;
lambda = ccp.tangentMass * (-vt);
// b2Clamp the accumulated impulse
var maxFriction = c.friction * ccp.normalImpulse;
newImpulse = b2Math.b2Clamp(ccp.tangentImpulse + lambda, -maxFriction, maxFriction);
lambda = newImpulse - ccp.tangentImpulse;
// Apply contact impulse
//P = b2Math.MulFV(lambda, tangent);
PX = lambda * tangentX;
PY = lambda * tangentY;
//b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
b1_linearVelocity.x -= invMass1 * PX;
b1_linearVelocity.y -= invMass1 * PY;
b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);
//b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
b2_linearVelocity.x += invMass2 * PX;
b2_linearVelocity.y += invMass2 * PY;
b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);
ccp.tangentImpulse = newImpulse;
}
// Solver tangent constraints
// MOVED ABOVE FOR EFFICIENCY
/*for (j = 0; j < tCount; ++j)
{
ccp = c.points[ j ];
//r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
tMat = b1.m_R;
tVec = ccp.localAnchor1;
r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
//r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
tMat = b2.m_R;
tVec = ccp.localAnchor2;
r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
// Relative velocity at contact
//var dv = b2.m_linearVelocity + b2Cross(b2.m_angularVelocity, r2) - b1.m_linearVelocity - b2Cross(b1.m_angularVelocity, r1);
//dv = b2Math.SubtractVV(b2Math.SubtractVV(b2Math.AddVV(b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);
// Compute tangent impulse
var vt = dvX*tangentX + dvY*tangentY;
lambda = ccp.tangentMass * (-vt);
// b2Clamp the accumulated impulse
var maxFriction = c.friction * ccp.normalImpulse;
newImpulse = b2Math.b2Clamp(ccp.tangentImpulse + lambda, -maxFriction, maxFriction);
lambda = newImpulse - ccp.tangentImpulse;
// Apply contact impulse
//P = b2Math.MulFV(lambda, tangent);
PX = lambda * tangentX;
PY = lambda * tangentY;
//b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
b1_linearVelocity.x -= invMass1 * PX;
b1_linearVelocity.y -= invMass1 * PY;
b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);
//b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
b2_linearVelocity.x += invMass2 * PX;
b2_linearVelocity.y += invMass2 * PY;
b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);
ccp.tangentImpulse = newImpulse;
}*/
// Update angular velocity
b1.m_angularVelocity = b1_angularVelocity;
b2.m_angularVelocity = b2_angularVelocity;
}
},
SolvePositionConstraints: function(beta){
var minSeparation = 0.0;
var tMat;
var tVec;
for (var i = 0; i < this.m_constraintCount; ++i)
{
var c = this.m_constraints[ i ];
var b1 = c.body1;
var b2 = c.body2;
var b1_position = b1.m_position;
var b1_rotation = b1.m_rotation;
var b2_position = b2.m_position;
var b2_rotation = b2.m_rotation;
var invMass1 = b1.m_invMass;
var invI1 = b1.m_invI;
var invMass2 = b2.m_invMass;
var invI2 = b2.m_invI;
//var normal = new b2Vec2(c.normal.x, c.normal.y);
var normalX = c.normal.x;
var normalY = c.normal.y;
//var tangent = b2Math.b2CrossVF(normal, 1.0);
var tangentX = normalY;
var tangentY = -normalX;
// Solver normal constraints
var tCount = c.pointCount;
for (var j = 0; j < tCount; ++j)
{
var ccp = c.points[ j ];
//r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
tMat = b1.m_R;
tVec = ccp.localAnchor1;
var r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
var r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
//r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
tMat = b2.m_R;
tVec = ccp.localAnchor2;
var r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
var r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
//var p1 = b2Math.AddVV(b1.m_position, r1);
var p1X = b1_position.x + r1X;
var p1Y = b1_position.y + r1Y;
//var p2 = b2Math.AddVV(b2.m_position, r2);
var p2X = b2_position.x + r2X;
var p2Y = b2_position.y + r2Y;
//var dp = b2Math.SubtractVV(p2, p1);
var dpX = p2X - p1X;
var dpY = p2Y - p1Y;
// Approximate the current separation.
//var separation = b2Math.b2Dot(dp, normal) + ccp.separation;
var separation = (dpX*normalX + dpY*normalY) + ccp.separation;
// Track max constraint error.
minSeparation = b2Math.b2Min(minSeparation, separation);
// Prevent large corrections and allow slop.
var C = beta * b2Math.b2Clamp(separation + b2Settings.b2_linearSlop, -b2Settings.b2_maxLinearCorrection, 0.0);
// Compute normal impulse
var dImpulse = -ccp.normalMass * C;
// b2Clamp the accumulated impulse
var impulse0 = ccp.positionImpulse;
ccp.positionImpulse = b2Math.b2Max(impulse0 + dImpulse, 0.0);
dImpulse = ccp.positionImpulse - impulse0;
//var impulse = b2Math.MulFV( dImpulse, normal );
var impulseX = dImpulse * normalX;
var impulseY = dImpulse * normalY;
//b1.m_position.Subtract( b2Math.MulFV( invMass1, impulse ) );
b1_position.x -= invMass1 * impulseX;
b1_position.y -= invMass1 * impulseY;
b1_rotation -= invI1 * (r1X * impulseY - r1Y * impulseX);
b1.m_R.Set(b1_rotation);
//b2.m_position.Add( b2Math.MulFV( invMass2, impulse ) );
b2_position.x += invMass2 * impulseX;
b2_position.y += invMass2 * impulseY;
b2_rotation += invI2 * (r2X * impulseY - r2Y * impulseX);
b2.m_R.Set(b2_rotation);
}
// Update body rotations
b1.m_rotation = b1_rotation;
b2.m_rotation = b2_rotation;
}
return minSeparation >= -b2Settings.b2_linearSlop;
},
PostSolve: function(){
for (var i = 0; i < this.m_constraintCount; ++i)
{
var c = this.m_constraints[ i ];
var m = c.manifold;
for (var j = 0; j < c.pointCount; ++j)
{
var mPoint = m.points[j];
var cPoint = c.points[j];
mPoint.normalImpulse = cPoint.normalImpulse;
mPoint.tangentImpulse = cPoint.tangentImpulse;
}
}
},
m_allocator: null,
m_constraints: new Array(),
m_constraintCount: 0};
(C) Æliens
20/2/2008
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
