@theatrejs/theatrejs
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🎮 A JavaScript 2D Game Engine focused on creating pixel art games.
291 lines (207 loc) • 7.67 kB
JavaScript
import {AABB, Actor, COLLIDERTYPES, Stage, System, Vector2} from '../index.js';
/**
* Creates collision systems.
*
* @example
*
* const system = new SystemCollision();
*/
class SystemCollision extends System {
/**
* @typedef {Array<Actor>} TypePairActor A pair of actors.
* @private
*/
/**
* Stores the current collision pairs.
* @type {Array<TypePairActor>}
* @private
*/
$current;
/**
* Stores the previous collision pairs.
* @type {Array<TypePairActor>}
* @private
*/
$previous;
/**
* Creates a new collision system.
*/
constructor() {
super();
}
/**
* Checks if a collision previously existed between two given actors.
* @param {Actor} $dynamic The first actor to check on.
* @param {Actor} $inert The second actor to check with.
* @returns {boolean}
* @private
*/
$hasCollisionPrevious($dynamic, $inert) {
const result = this.$previous.find(([$dynamicPrevious, $inertPrevious]) => {
return $dynamic === $dynamicPrevious
&& $inert === $inertPrevious;
});
return typeof result !== 'undefined';
}
/**
* Called when the system is being initiated.
* @public
*/
onInitiate() {
this.$current = [];
this.$previous = [];
}
/**
* Called when the system is being updated by one tick update.
* @param {Object} $parameters The given parameters.
* @param {Stage} $parameters.$stage The stage on which to execute the system.
* @param {number} $parameters.$timetick The tick duration (in ms).
* @public
*/
onTick({$stage}) {
/**
* @typedef {Object} TypePairCollision A pair of candidates for collision.
* @property {number} TypePairCollision.$distance The manhattan distance between the two actors.
* @property {Actor} TypePairCollision.$dynamic The first actor.
* @property {Actor} TypePairCollision.$inert The second actor.
* @private
*/
/**
* @type {Array<TypePairCollision>}
*/
const pairs = [];
/**
* @type {Array<Actor>}
*/
const dynamics = [];
/**
* @type {Array<Actor>}
*/
const kinetics = [];
/**
* @type {Array<Actor>}
*/
const statics = [];
$stage.actors.forEach(($actor) => {
if ($actor.hasCollider() === false) {
return;
}
switch ($actor.collider.type) {
case COLLIDERTYPES.DYNAMIC: {
dynamics.push($actor);
break;
}
case COLLIDERTYPES.KINETIC: {
kinetics.push($actor);
break;
}
case COLLIDERTYPES.STATIC: {
statics.push($actor);
break;
}
}
});
const inerts = [...statics, ...kinetics];
if (inerts.length === 0) {
return;
}
dynamics.forEach(($dynamic) => {
const boundariesDynamic = $dynamic.collider.boundaries.clone().translate($dynamic.translation);
const centerBoundariesDynamic = new AABB(boundariesDynamic.center, boundariesDynamic.center);
inerts.forEach(($inert) => {
const boundariesInert = $inert.collider.boundaries.clone().translate($inert.translation);
const distance = AABB.distanceManhattan(centerBoundariesDynamic, boundariesInert);
pairs.push({
$distance: distance,
$dynamic: $dynamic,
$inert: $inert
});
});
});
pairs.sort(($a, $b) => {
return $a.$distance - $b.$distance;
});
pairs.forEach(($pair) => {
const {$dynamic, $inert} = $pair;
if ($stage.hasActor($dynamic) === false) {
return;
}
if ($stage.hasActor($inert) === false) {
return;
}
const boundariesDynamic = $dynamic.collider.boundaries.clone().translate($dynamic.translation);
const boundariesInert = $inert.collider.boundaries.clone().translate($inert.translation);
const overlapX = AABB.overlapX(boundariesDynamic, boundariesInert);
if (overlapX <= 0) {
return;
}
const overlapY = AABB.overlapY(boundariesDynamic, boundariesInert);
if (overlapY <= 0) {
return;
}
this.$current.push([$dynamic, $inert]);
const directionX = Math.sign($inert.translation.x - $dynamic.translation.x);
const directionY = Math.sign($inert.translation.y - $dynamic.translation.y);
const checkMinimumX = (overlapX <= overlapY);
const checkMinimumY = (overlapY <= overlapX);
if ($dynamic.collider.traversable === false
&& $inert.collider.traversable === false) {
const resolverDynamic = new Vector2(
checkMinimumX ? - directionX * overlapX : 0,
checkMinimumY ? - directionY * overlapY : 0
);
$dynamic.translate(resolverDynamic);
}
const originDynamicEast = checkMinimumX === true && directionX === 1;
const originDynamicNorth = checkMinimumY === true && directionY === 1;
const originDynamicSouth = checkMinimumY === true && directionY === -1;
const originDynamicWest = checkMinimumX === true && directionX === -1;
if (this.$hasCollisionPrevious($dynamic, $inert) === false) {
$dynamic.onCollideEnter({
$actor: $inert,
$east: originDynamicEast,
$north: originDynamicNorth,
$south: originDynamicSouth,
$west: originDynamicWest
});
$inert.onCollideEnter({
$actor: $dynamic,
$east: originDynamicWest,
$north: originDynamicSouth,
$south: originDynamicNorth,
$west: originDynamicEast
});
}
$dynamic.onCollide({
$actor: $inert,
$east: originDynamicEast,
$north: originDynamicNorth,
$south: originDynamicSouth,
$west: originDynamicWest
});
$inert.onCollide({
$actor: $dynamic,
$east: originDynamicWest,
$north: originDynamicSouth,
$south: originDynamicNorth,
$west: originDynamicEast
});
});
this.$previous.filter(([$dynamicPrevious, $inertPrevious]) => {
const result = this.$current.find(([$dynamic, $inert]) => {
return $dynamic === $dynamicPrevious
&& $inert === $inertPrevious;
});
return typeof result === 'undefined';
}).forEach(([$dynamicPrevious, $inertPrevious]) => {
$dynamicPrevious.onCollideLeave($inertPrevious);
$inertPrevious.onCollideLeave($dynamicPrevious);
});
this.$previous = [...this.$current];
this.$current = [];
}
}
export {
SystemCollision
};
export default SystemCollision;