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improved delta consistency
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@liabru
liabru committed Jan 1, 2022
1 parent 11d5e73 commit 87af8a1
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Showing 3 changed files with 27 additions and 28 deletions.
44 changes: 21 additions & 23 deletions src/collision/Resolver.js
View file
Expand Up @@ -9,17 +9,17 @@ var Resolver = {};
module.exports = Resolver;

var Vertices = require('../geometry/Vertices');
var Vector = require('../geometry/Vector');
var Common = require('../core/Common');
var Bounds = require('../geometry/Bounds');

(function() {

Resolver._restingThresh = 4;
Resolver._restingThreshTangent = 6;
Resolver._restingThresh = 2;
Resolver._restingThreshTangent = Math.sqrt(6);
Resolver._positionDampen = 0.9;
Resolver._positionWarming = 0.8;
Resolver._frictionNormalMultiplier = 5;
Resolver._frictionMaxStatic = Number.MAX_VALUE;

/**
* Prepare pairs for position solving.
Expand Down Expand Up @@ -49,9 +49,9 @@ var Bounds = require('../geometry/Bounds');
* Find a solution for pair positions.
* @method solvePosition
* @param {pair[]} pairs
* @param {number} delta
* @param {number} positionIterations
*/
Resolver.solvePosition = function(pairs, delta) {
Resolver.solvePosition = function(pairs, positionIterations) {
var i,
pair,
collision,
Expand All @@ -60,9 +60,7 @@ var Bounds = require('../geometry/Bounds');
normal,
contactShare,
positionImpulse,
timeScale = delta / Common._timeUnit,
damping = Common.clamp(Resolver._positionDampen * timeScale, 0, 1),
positionDampen = Resolver._positionDampen,
positionDampen = Resolver._positionDampen * Common.clamp(20 / positionIterations, 0, 1),
pairsLength = pairs.length;

// find impulses required to resolve penetration
Expand Down Expand Up @@ -93,7 +91,7 @@ var Bounds = require('../geometry/Bounds');
bodyA = collision.parentA;
bodyB = collision.parentB;
normal = collision.normal;
positionImpulse = (pair.separation - pair.slop) * damping;
positionImpulse = pair.separation - pair.slop;

if (bodyA.isStatic || bodyB.isStatic)
positionImpulse *= 2;
Expand Down Expand Up @@ -227,12 +225,12 @@ var Bounds = require('../geometry/Bounds');
*/
Resolver.solveVelocity = function(pairs, delta) {
var timeScale = delta / Common._timeUnit,
timeScale2 = timeScale * timeScale,
timeScale3 = timeScale2 * timeScale,
restingThresh = Resolver._restingThresh * timeScale2,
timeScaleSquared = timeScale * timeScale,
timeScaleCubed = timeScaleSquared * timeScale,
restingThresh = -Resolver._restingThresh * timeScale,
frictionNormalMultiplier = Resolver._frictionNormalMultiplier,
restingThreshTangent = Resolver._restingThreshTangent * timeScale2,
NumberMaxValue = Number.MAX_VALUE,
restingThreshTangent = Resolver._restingThreshTangent * timeScale,
frictionMaxStatic = Resolver._frictionMaxStatic * timeScale,
pairsLength = pairs.length,
tangentImpulse,
maxFriction,
Expand All @@ -258,7 +256,7 @@ var Bounds = require('../geometry/Bounds');
contactsLength = contacts.length,
contactShare = 1 / contactsLength,
inverseMassTotal = bodyA.inverseMass + bodyB.inverseMass,
friction = pair.friction * pair.frictionStatic * frictionNormalMultiplier * timeScale2;
friction = pair.friction * pair.frictionStatic * frictionNormalMultiplier * timeScale;

// update body velocities
bodyAVelocity.x = bodyA.position.x - bodyA.positionPrev.x;
Expand Down Expand Up @@ -291,14 +289,14 @@ var Bounds = require('../geometry/Bounds');

// coulomb friction
var normalOverlap = pair.separation + normalVelocity;
var normalForce = Math.min(normalOverlap, 1) * timeScale3;
var normalForce = Math.min(normalOverlap, 1);
normalForce = normalOverlap < 0 ? 0 : normalForce;

var frictionLimit = normalForce * friction;

if (tangentVelocity > frictionLimit || -tangentVelocity > frictionLimit) {
maxFriction = (tangentVelocity > 0 ? tangentVelocity : -tangentVelocity) * timeScale;
tangentImpulse = pair.friction * (tangentVelocity > 0 ? 1 : -1) * timeScale3;
if (tangentVelocity < -frictionLimit || tangentVelocity > frictionLimit) {
maxFriction = (tangentVelocity > 0 ? tangentVelocity : -tangentVelocity);
tangentImpulse = pair.friction * (tangentVelocity > 0 ? 1 : -1) * timeScaleCubed;

if (tangentImpulse < -maxFriction) {
tangentImpulse = -maxFriction;
Expand All @@ -307,7 +305,7 @@ var Bounds = require('../geometry/Bounds');
}
} else {
tangentImpulse = tangentVelocity;
maxFriction = NumberMaxValue;
maxFriction = frictionMaxStatic;
}

// account for mass, inertia and contact offset
Expand All @@ -320,20 +318,20 @@ var Bounds = require('../geometry/Bounds');
tangentImpulse *= share;

// handle high velocity and resting collisions separately
if (normalVelocity < 0 && normalVelocity * normalVelocity > restingThresh) {
if (normalVelocity < restingThresh) {
// high normal velocity so clear cached contact normal impulse
contact.normalImpulse = 0;
} else {
// solve resting collision constraints using Erin Catto's method (GDC08)
// impulse constraint tends to 0
var contactNormalImpulse = contact.normalImpulse;
contact.normalImpulse += normalImpulse;
contact.normalImpulse = Math.min(contact.normalImpulse, 0);
if (contact.normalImpulse > 0) contact.normalImpulse = 0;
normalImpulse = contact.normalImpulse - contactNormalImpulse;
}

// handle high velocity and resting collisions separately
if (tangentVelocity * tangentVelocity > restingThreshTangent) {
if (tangentVelocity < -restingThreshTangent || tangentVelocity > restingThreshTangent) {
// high tangent velocity so clear cached contact tangent impulse
contact.tangentImpulse = 0;
} else {
Expand Down
2 changes: 1 addition & 1 deletion src/core/Engine.js
View file
Expand Up @@ -154,7 +154,7 @@ var Body = require('../body/Body');
// iteratively resolve position between collisions
Resolver.preSolvePosition(pairs.list);
for (i = 0; i < engine.positionIterations; i++) {
Resolver.solvePosition(pairs.list, delta);
Resolver.solvePosition(pairs.list, engine.positionIterations);
}
Resolver.postSolvePosition(allBodies);

Expand Down
9 changes: 5 additions & 4 deletions src/core/Sleeping.js
View file
Expand Up @@ -25,8 +25,8 @@ var Common = require('./Common');
*/
Sleeping.update = function(bodies, delta) {
var timeScale = delta / Common._timeUnit,
timeScale2 = timeScale * timeScale,
motionSleepThreshold = Sleeping._motionSleepThreshold * timeScale2;
timeScaleSquared = timeScale * timeScale,
motionSleepThreshold = Sleeping._motionSleepThreshold * timeScaleSquared;

// update bodies sleeping status
for (var i = 0; i < bodies.length; i++) {
Expand Down Expand Up @@ -64,7 +64,8 @@ var Common = require('./Common');
* @param {number} delta
*/
Sleeping.afterCollisions = function(pairs, delta) {
var timeScale = delta / Common._timeUnit;
var timeScale = delta / Common._timeUnit,
motionSleepThreshold = Sleeping._motionSleepThreshold * timeScale * timeScale;

// wake up bodies involved in collisions
for (var i = 0; i < pairs.length; i++) {
Expand All @@ -86,7 +87,7 @@ var Common = require('./Common');
var sleepingBody = (bodyA.isSleeping && !bodyA.isStatic) ? bodyA : bodyB,
movingBody = sleepingBody === bodyA ? bodyB : bodyA;

if (!sleepingBody.isStatic && movingBody.motion > Sleeping._motionWakeThreshold * timeScale * timeScale) {
if (!sleepingBody.isStatic && movingBody.motion > motionSleepThreshold) {
Sleeping.set(sleepingBody, false);
}
}
Expand Down

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