Force objects define the general and occasional forces to be applied to each particle in the particle system as the animation progresses - a gravity force object is pre-defined by Scrawl-canvas.
import { constructors } from '../core/library.js';
import { doCreate, isa_fn, mergeOver, pushUnique, λnull, Ωempty } from '../helper/utilities.js';
import { releaseVector, requestVector } from '../untracked-factory/vector.js';
import baseMix from '../mixin/base.js';Shared constants (none imported)
Local constants
const FORCE = 'force',
GRAVITY = 'gravity',
T_FORCE = 'Force';const Force = function (items = Ωempty) {
this.makeName(items.name);
this.register();
this.set(this.defs);
this.set(items);
if (!this.action) this.action = λnull;
return this;
};const P = Force.prototype = doCreate();
P.type = T_FORCE;
P.lib = FORCE;
P.isArtefact = false;
P.isAsset = false;baseMix(P);const defaultAttributes = {
action: null,
};
P.defs = mergeOver(P.defs, defaultAttributes);P.packetFunctions = pushUnique(P.packetFunctions, ['action']);P.kill = function () {
this.deregister();
return true;
};const S = P.setters;
S.action = function (item) {
if (isa_fn(item)) this.action = item;
else this.action = λnull;
};let myRepellorBall = scrawl.makeWheel({
name: 'big-ball',
radius: 30,
});
scrawl.makeForce({
name: 'example-repellor',
action: (particle, world, host) => {
let {load, position} = particle;
let ballPosition = myRepellorBall.get('position');
let tempVector = scrawl.requestVector(ballPosition).vectorSubtract(position);
let magnitude = tempVector.getMagnitude();
if (magnitude && magnitude < myRepellorBall.get('radius')) {
tempVector.scalarMultiply(1 / (magnitude / 1000));
load.vectorSubtract(tempVector)
}
scrawl.releaseVector(tempVector);
},
});
export const makeForce = function (items) {
if (!items) return false;
return new Force(items);
};
constructors.Force = Force;makeForce({
name: GRAVITY,
action: (particle, world) => {
const {mass, load} = particle;
const c = requestVector();
c.setFromVector(world.gravity).scalarMultiply(mass);
load.vectorAdd(c);
releaseVector(c);
},
});