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The MatterAttractors plugin, which enables attractors between bodie…
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…s, has been fixed. The original plugin only worked if the body with the attractor was _first_ in the world bodies list. It can now attract any body, no matter where in the world list it is. Fix #5160
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@photonstorm
photonstorm committed Jul 23, 2020
1 parent 0999824 commit fb1306e
Showing 1 changed file with 113 additions and 96 deletions.
209 changes: 113 additions & 96 deletions src/physics/matter-js/lib/plugins/MatterAttractors.js
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Expand Up @@ -5,108 +5,125 @@ var Matter = require('../../CustomMain');
* See the readme for usage and examples.
* @module MatterAttractors
*/
var MatterAttractors = {
// plugin meta
name: 'matter-attractors', // PLUGIN_NAME
version: '0.1.7', // PLUGIN_VERSION
for: 'matter-js@^0.14.2',
silent: true, // no console log please

// installs the plugin where `base` is `Matter`
// you should not need to call this directly.
install: function(base) {
base.after('Body.create', function() {
MatterAttractors.Body.init(this);
});

base.before('Engine.update', function(engine) {
MatterAttractors.Engine.update(engine);
});
},

Body: {
/**
* Initialises the `body` to support attractors.
* This is called automatically by the plugin.
* @function MatterAttractors.Body.init
* @param {Matter.Body} body The body to init.
* @returns {void} No return value.
*/
init: function(body) {
body.plugin.attractors = body.plugin.attractors || [];
}
},

Engine: {
/**
* Applies all attractors for all bodies in the `engine`.
* This is called automatically by the plugin.
* @function MatterAttractors.Engine.update
* @param {Matter.Engine} engine The engine to update.
* @returns {void} No return value.
*/
update: function(engine) {
var world = engine.world,
bodies = Matter.Composite.allBodies(world);

for (var i = 0; i < bodies.length; i += 1) {
var bodyA = bodies[i],
attractors = bodyA.plugin.attractors;

if (attractors && attractors.length > 0) {
for (var j = i + 1; j < bodies.length; j += 1) {
var bodyB = bodies[j];

for (var k = 0; k < attractors.length; k += 1) {
var attractor = attractors[k],
forceVector = attractor;

if (Matter.Common.isFunction(attractor)) {
forceVector = attractor(bodyA, bodyB);
}

if (forceVector) {
Matter.Body.applyForce(bodyB, bodyB.position, forceVector);
}
var MatterAttractors =
{
name: 'matter-attractors',
version: '0.1.7',
for: 'matter-js@^0.14.2',
silent: true,

// installs the plugin where `base` is `Matter`
// you should not need to call this directly.
install: function (base)
{
base.after('Body.create', function ()
{
MatterAttractors.Body.init(this);
});

base.before('Engine.update', function (engine)
{
MatterAttractors.Engine.update(engine);
});
},

Body:
{
/**
* Initialises the `body` to support attractors.
* This is called automatically by the plugin.
* @function MatterAttractors.Body.init
* @param {Matter.Body} body The body to init.
* @returns {void} No return value.
*/
init: function (body)
{
body.plugin.attractors = body.plugin.attractors || [];
}
},

Engine:
{
/**
* Applies all attractors for all bodies in the `engine`.
* This is called automatically by the plugin.
* @function MatterAttractors.Engine.update
* @param {Matter.Engine} engine The engine to update.
* @returns {void} No return value.
*/
update: function (engine)
{
var bodies = Matter.Composite.allBodies(engine.world);

for (var i = 0; i < bodies.length; i++)
{
var bodyA = bodies[i];
var attractors = bodyA.plugin.attractors;

if (attractors && attractors.length > 0)
{
for (var j = 0; j < bodies.length; j++)
{
var bodyB = bodies[j];

if (i !== j)
{
for (var k = 0; k < attractors.length; k++)
{
var attractor = attractors[k];
var forceVector = attractor;

if (Matter.Common.isFunction(attractor))
{
forceVector = attractor(bodyA, bodyB);
}

if (forceVector)
{
Matter.Body.applyForce(bodyB, bodyB.position, forceVector);
}
}
}
}
}
}
}
}
}
}
},

/**
* Defines some useful common attractor functions that can be used
* by pushing them to your body's `body.plugin.attractors` array.
* @namespace MatterAttractors.Attractors
* @property {number} gravityConstant The gravitational constant used by the gravity attractor.
*/
Attractors: {
gravityConstant: 0.001,
},

/**
* An attractor function that applies Newton's law of gravitation.
* Use this by pushing `MatterAttractors.Attractors.gravity` to your body's `body.plugin.attractors` array.
* The gravitational constant defaults to `0.001` which you can change
* at `MatterAttractors.Attractors.gravityConstant`.
* @function MatterAttractors.Attractors.gravity
* @param {Matter.Body} bodyA The first body.
* @param {Matter.Body} bodyB The second body.
* @returns {void} No return value.
* Defines some useful common attractor functions that can be used
* by pushing them to your body's `body.plugin.attractors` array.
* @namespace MatterAttractors.Attractors
* @property {number} gravityConstant The gravitational constant used by the gravity attractor.
*/
gravity: function(bodyA, bodyB) {
// use Newton's law of gravitation
var bToA = Matter.Vector.sub(bodyB.position, bodyA.position),
distanceSq = Matter.Vector.magnitudeSquared(bToA) || 0.0001,
normal = Matter.Vector.normalise(bToA),
magnitude = -MatterAttractors.Attractors.gravityConstant * (bodyA.mass * bodyB.mass / distanceSq),
force = Matter.Vector.mult(normal, magnitude);

// to apply forces to both bodies
Matter.Body.applyForce(bodyA, bodyA.position, Matter.Vector.neg(force));
Matter.Body.applyForce(bodyB, bodyB.position, force);
Attractors:
{
gravityConstant: 0.001,

/**
* An attractor function that applies Newton's law of gravitation.
* Use this by pushing `MatterAttractors.Attractors.gravity` to your body's `body.plugin.attractors` array.
* The gravitational constant defaults to `0.001` which you can change
* at `MatterAttractors.Attractors.gravityConstant`.
* @function MatterAttractors.Attractors.gravity
* @param {Matter.Body} bodyA The first body.
* @param {Matter.Body} bodyB The second body.
* @returns {void} No return value.
*/
gravity: function (bodyA, bodyB)
{
// use Newton's law of gravitation
var bToA = Matter.Vector.sub(bodyB.position, bodyA.position);
var distanceSq = Matter.Vector.magnitudeSquared(bToA) || 0.0001;
var normal = Matter.Vector.normalise(bToA);
var magnitude = -MatterAttractors.Attractors.gravityConstant * (bodyA.mass * bodyB.mass / distanceSq);
var force = Matter.Vector.mult(normal, magnitude);

// to apply forces to both bodies
Matter.Body.applyForce(bodyA, bodyA.position, Matter.Vector.neg(force));
Matter.Body.applyForce(bodyB, bodyB.position, force);
}
}
}
};

module.exports = MatterAttractors;
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