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[#1091] new Detector class to be instantiated by each physic world …
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…instance to detect and solve collisions
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@obiot
obiot committed Dec 28, 2022
1 parent 2bd4c54 commit 99d4a8c
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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### Changed
- General: further code revamping to make melonJS more modular and allow instantiation of different app/games
- Physic: new `Detector` class instantiated by each physic world instance to detect and solve collisions

### Fixed
- Doc: fix `fps` type in the World class

## [14.2.0] (melonJS 2) - _2022-12-26_

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4 changes: 2 additions & 2 deletions src/physics/collision.js
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@@ -1,4 +1,4 @@
import { rayCast } from "./detector.js";
import { game } from "../index.js";

/**
* Collision detection (and projection-based collision response) of 2D shapes.<br>
Expand Down Expand Up @@ -117,7 +117,7 @@ var collision = {
* // ...
* }
*/
rayCast(line, result) { return rayCast(line, result); }
rayCast(line, result) { return game.world.rayCast(line, result); }
};

export default collision;
317 changes: 172 additions & 145 deletions src/physics/detector.js
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@@ -1,10 +1,8 @@
import * as SAT from "./sat.js";
import ResponseObject from "./response.js";
import Vector2d from "./../math/vector2.js";
import { game } from "../index.js";
import Bounds from "./bounds.js";


// a dummy object when using Line for raycasting
let dummyObj = {
pos : new Vector2d(0, 0),
Expand All @@ -16,167 +14,196 @@ let dummyObj = {
}
};

// some cache bounds object used for collision detection
let boundsA = new Bounds();
let boundsB = new Bounds();

// the global response object used for collisions
let globalResponse = new ResponseObject();

/**
* a function used to determine if two objects should collide (based on both respective objects collision mask and type).<br>
* you can redefine this function if you need any specific rules over what should collide with what.
* @ignore
* @param {Renderable} a - a reference to the object A.
* @param {Renderable} b - a reference to the object B.
* @returns {boolean} true if they should collide, false otherwise
* the Detector class contains methods for detecting collisions between bodies using a broadphase algorithm.
*/
function shouldCollide(a, b) {
var bodyA = a.body,
bodyB = b.body;
return (
a !== b &&
a.isKinematic !== true && b.isKinematic !== true &&
typeof bodyA === "object" && typeof bodyB === "object" &&
bodyA.shapes.length > 0 && bodyB.shapes.length > 0 &&
!(bodyA.isStatic === true && bodyB.isStatic === true) &&
(bodyA.collisionMask & bodyB.collisionType) !== 0 &&
(bodyA.collisionType & bodyB.collisionMask) !== 0
);
}



/**
* find all the collisions for the specified object
* @ignore
* @param {Renderable} objA - object to be tested for collision
* @param {ResponseObject} [response] - a user defined response object that will be populated if they intersect.
* @returns {boolean} in case of collision, false otherwise
*/
export function collisionCheck(objA, response = globalResponse) {
var collisionCounter = 0;
// retreive a list of potential colliding objects from the game world
var candidates = game.world.broadphase.retrieve(objA);
export default class Detector {
/**
* @param {Container} world - the physic world this detector is bind to
*/
constructor(world) {
// @ignore
this.world = world;

/**
* the default response object used for collisions
* (will be automatically populated by the collides functions)
* @type {ResponseObject}
*/
this.response = new ResponseObject();
}

boundsA.addBounds(objA.getBounds(), true);
boundsA.addBounds(objA.body.getBounds());
/**
* determine if two objects should collide (based on both respective objects body collision mask and type).<br>
* you can redefine this function if you need any specific rules over what should collide with what.
* @param {Renderable} a - a reference to the object A.
* @param {Renderable} b - a reference to the object B.
* @returns {boolean} true if they should collide, false otherwise
*/
shouldCollide(a, b) {
var bodyA = a.body,
bodyB = b.body;
return (
(typeof bodyA === "object" && typeof bodyB === "object") &&
a !== b &&
a.isKinematic !== true && b.isKinematic !== true &&
bodyA.shapes.length > 0 && bodyB.shapes.length > 0 &&
!(bodyA.isStatic === true && bodyB.isStatic === true) &&
(bodyA.collisionMask & bodyB.collisionType) !== 0 &&
(bodyA.collisionType & bodyB.collisionMask) !== 0
);
}

candidates.forEach((objB) => {
// check if both objects "should" collide
if (shouldCollide(objA, objB)) {
/**
* detect collision between two bodies.
* @param {Body} bodyA - a reference to body A.
* @param {Body} bodyB - a reference to body B.
* @returns {Boolean} true if colliding
*/
collides(bodyA, bodyB, response = this.response) {
// for each shape in body A
for (var indexA = bodyA.shapes.length, shapeA; indexA--, (shapeA = bodyA.shapes[indexA]);) {
// for each shape in body B
for (var indexB = bodyB.shapes.length, shapeB; indexB--, (shapeB = bodyB.shapes[indexB]);) {
// full SAT collision check
if (SAT["test" + shapeA.shapeType + shapeB.shapeType].call(
this,
bodyA.ancestor, // a reference to the object A
shapeA,
bodyB.ancestor, // a reference to the object B
shapeB,
// clear response object before reusing
response.clear()) === true
) {

boundsB.addBounds(objB.getBounds(), true);
boundsB.addBounds(objB.body.getBounds());
// set the shape index
response.indexShapeA = indexA;
response.indexShapeB = indexB;

// fast AABB check if both bounding boxes are overlaping
if (boundsA.overlaps(boundsB)) {
// for each shape in body A
objA.body.shapes.forEach((shapeA, indexA) => {
// for each shape in body B
objB.body.shapes.forEach((shapeB, indexB) => {
// full SAT collision check
if (SAT["test" + shapeA.shapeType + shapeB.shapeType].call(
this,
objA, // a reference to the object A
shapeA,
objB, // a reference to the object B
shapeB,
// clear response object before reusing
response.clear()) === true
) {
// we touched something !
collisionCounter++;

// set the shape index
response.indexShapeA = indexA;
response.indexShapeB = indexB;

// execute the onCollision callback
if (objA.onCollision && objA.onCollision(response, objB) !== false && objA.body.isStatic === false) {
objA.body.respondToCollision.call(objA.body, response);
}
if (objB.onCollision && objB.onCollision(response, objA) !== false && objB.body.isStatic === false) {
objB.body.respondToCollision.call(objB.body, response);
}
}
});
});
return true;
}
}
}
});
// we could return the amount of objects we collided with ?
return collisionCounter > 0;
}

/**
* Checks for object colliding with the given line
* @ignore
* @param {Line} line - line to be tested for collision
* @param {Array.<Renderable>} [result] - a user defined array that will be populated with intersecting physic objects.
* @returns {Array.<Renderable>} an array of intersecting physic objects
* @example
* // define a line accross the viewport
* var ray = new me.Line(
* // absolute position of the line
* 0, 0, [
* // starting point relative to the initial position
* new me.Vector2d(0, 0),
* // ending point
* new me.Vector2d(me.game.viewport.width, me.game.viewport.height)
* ]);
*
* // check for collition
* result = me.collision.rayCast(ray);
*
* if (result.length > 0) {
* // ...
* }
*/
export function rayCast(line, result = []) {
var collisionCounter = 0;

// retrieve a list of potential colliding objects from the game world
var candidates = game.world.broadphase.retrieve(line);

for (var i = candidates.length, objB; i--, (objB = candidates[i]);) {

// fast AABB check if both bounding boxes are overlaping
if (objB.body && line.getBounds().overlaps(objB.getBounds())) {
return false;
}

// go trough all defined shapes in B (if any)
var bLen = objB.body.shapes.length;
if ( objB.body.shapes.length === 0) {
continue;
/**
* find all the collisions for the specified object using a broadphase algorithm
* @ignore
* @param {Renderable} objA - object to be tested for collision
* @returns {boolean} in case of collision, false otherwise
*/
collisions(objA) {
var collisionCounter = 0;
// retreive a list of potential colliding objects from the game world
var candidates = this.world.broadphase.retrieve(objA);

boundsA.addBounds(objA.getBounds(), true);
boundsA.addBounds(objA.body.getBounds());

candidates.forEach((objB) => {
// check if both objects "should" collide
if (this.shouldCollide(objA, objB)) {

boundsB.addBounds(objB.getBounds(), true);
boundsB.addBounds(objB.body.getBounds());

// fast AABB check if both bounding boxes are overlaping
if (boundsA.overlaps(boundsB)) {

if (this.collides(objA.body, objB.body)) {
// we touched something !
collisionCounter++;

// execute the onCollision callback
if (objA.onCollision && objA.onCollision(this.response, objB) !== false && objA.body.isStatic === false) {
objA.body.respondToCollision.call(objA.body, this.response);
}
if (objB.onCollision && objB.onCollision(this.response, objA) !== false && objB.body.isStatic === false) {
objB.body.respondToCollision.call(objB.body, this.response);
}
}
}
}
});
// we could return the amount of objects we collided with ?
return collisionCounter > 0;
}

var shapeA = line;
/**
* Checks for object colliding with the given line
* @ignore
* @param {Line} line - line to be tested for collision
* @param {Array.<Renderable>} [result] - a user defined array that will be populated with intersecting physic objects.
* @returns {Array.<Renderable>} an array of intersecting physic objects
* @example
* // define a line accross the viewport
* var ray = new me.Line(
* // absolute position of the line
* 0, 0, [
* // starting point relative to the initial position
* new me.Vector2d(0, 0),
* // ending point
* new me.Vector2d(me.game.viewport.width, me.game.viewport.height)
* ]);
*
* // check for collition
* result = me.collision.rayCast(ray);
*
* if (result.length > 0) {
* // ...
* }
*/
rayCast(line, result = []) {
var collisionCounter = 0;

// retrieve a list of potential colliding objects from the game world
var candidates = this.world.broadphase.retrieve(line);

for (var i = candidates.length, objB; i--, (objB = candidates[i]);) {

// go through all defined shapes in B
var indexB = 0;
do {
var shapeB = objB.body.getShape(indexB);
// fast AABB check if both bounding boxes are overlaping
if (objB.body && line.getBounds().overlaps(objB.getBounds())) {

// full SAT collision check
if (SAT["test" + shapeA.shapeType + shapeB.shapeType]
.call(
this,
dummyObj, // a reference to the object A
shapeA,
objB, // a reference to the object B
shapeB
)) {
// we touched something !
result[collisionCounter] = objB;
collisionCounter++;
// go trough all defined shapes in B (if any)
var bLen = objB.body.shapes.length;
if ( objB.body.shapes.length === 0) {
continue;
}
indexB++;
} while (indexB < bLen);

var shapeA = line;

// go through all defined shapes in B
var indexB = 0;
do {
var shapeB = objB.body.getShape(indexB);

// full SAT collision check
if (SAT["test" + shapeA.shapeType + shapeB.shapeType]
.call(
this,
dummyObj, // a reference to the object A
shapeA,
objB, // a reference to the object B
shapeB
)) {
// we touched something !
result[collisionCounter] = objB;
collisionCounter++;
}
indexB++;
} while (indexB < bLen);
}
}
}

// cap result in case it was not empty
result.length = collisionCounter;
// cap result in case it was not empty
result.length = collisionCounter;

// return the list of colliding objects
return result;
// return the list of colliding objects
return result;
}
}

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