phaser/src/physics/matter-js/lib/factory/Composites.js

A fast, free and fun HTML5 Game Framework for Desktop and Mobile web browsers from the team at Phaser Studio Inc.

/**
* The `Matter.Composites` module contains factory methods for creating composite bodies
* with commonly used configurations (such as stacks and chains).
*
* See the included usage [examples](https://github.com/liabru/matter-js/tree/master/examples).
*
* @class Composites
*/

var Composites = {};

module.exports = Composites;

var Composite = require('../body/Composite');
var Constraint = require('../constraint/Constraint');
var Common = require('../core/Common');
var Body = require('../body/Body');
var Bodies = require('./Bodies');

(function() {

    /**
     * Create a new composite containing bodies created in the callback in a grid arrangement.
     * This function uses the body's bounds to prevent overlaps.
     * @method stack
     * @param {number} x Starting position in X.
     * @param {number} y Starting position in Y.
     * @param {number} columns
     * @param {number} rows
     * @param {number} columnGap
     * @param {number} rowGap
     * @param {function} callback
     * @return {composite} A new composite containing objects created in the callback
     */
    Composites.stack = function(x, y, columns, rows, columnGap, rowGap, callback) {
        var stack = Composite.create({ label: 'Stack' }),
            currentX = x,
            currentY = y,
            lastBody,
            i = 0;

        for (var row = 0; row < rows; row++) {
            var maxHeight = 0;

            for (var column = 0; column < columns; column++) {
                var body = callback(currentX, currentY, column, row, lastBody, i);

                if (body) {
                    var bodyHeight = body.bounds.max.y - body.bounds.min.y,
                        bodyWidth = body.bounds.max.x - body.bounds.min.x;

                    if (bodyHeight > maxHeight)
                        maxHeight = bodyHeight;

                    Body.translate(body, { x: bodyWidth * 0.5, y: bodyHeight * 0.5 });

                    currentX = body.bounds.max.x + columnGap;

                    Composite.addBody(stack, body);

                    lastBody = body;
                    i += 1;
                } else {
                    currentX += columnGap;
                }
            }

            currentY += maxHeight + rowGap;
            currentX = x;
        }

        return stack;
    };

    /**
     * Chains all bodies in the given composite together using constraints.
     * @method chain
     * @param {composite} composite
     * @param {number} xOffsetA
     * @param {number} yOffsetA
     * @param {number} xOffsetB
     * @param {number} yOffsetB
     * @param {object} options
     * @return {composite} A new composite containing objects chained together with constraints
     */
    Composites.chain = function(composite, xOffsetA, yOffsetA, xOffsetB, yOffsetB, options) {
        var bodies = composite.bodies;

        for (var i = 1; i < bodies.length; i++) {
            var bodyA = bodies[i - 1],
                bodyB = bodies[i],
                bodyAHeight = bodyA.bounds.max.y - bodyA.bounds.min.y,
                bodyAWidth = bodyA.bounds.max.x - bodyA.bounds.min.x,
                bodyBHeight = bodyB.bounds.max.y - bodyB.bounds.min.y,
                bodyBWidth = bodyB.bounds.max.x - bodyB.bounds.min.x;

            var defaults = {
                bodyA: bodyA,
                pointA: { x: bodyAWidth * xOffsetA, y: bodyAHeight * yOffsetA },
                bodyB: bodyB,
                pointB: { x: bodyBWidth * xOffsetB, y: bodyBHeight * yOffsetB }
            };

            var constraint = Common.extend(defaults, options);

            Composite.addConstraint(composite, Constraint.create(constraint));
        }

        composite.label += ' Chain';

        return composite;
    };

    /**
     * Connects bodies in the composite with constraints in a grid pattern, with optional cross braces.
     * @method mesh
     * @param {composite} composite
     * @param {number} columns
     * @param {number} rows
     * @param {boolean} crossBrace
     * @param {object} options
     * @return {composite} The composite containing objects meshed together with constraints
     */
    Composites.mesh = function(composite, columns, rows, crossBrace, options) {
        var bodies = composite.bodies,
            row,
            col,
            bodyA,
            bodyB,
            bodyC;

        for (row = 0; row < rows; row++) {
            for (col = 1; col < columns; col++) {
                bodyA = bodies[(col - 1) + (row * columns)];
                bodyB = bodies[col + (row * columns)];
                Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyA, bodyB: bodyB }, options)));
            }

            if (row > 0) {
                for (col = 0; col < columns; col++) {
                    bodyA = bodies[col + ((row - 1) * columns)];
                    bodyB = bodies[col + (row * columns)];
                    Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyA, bodyB: bodyB }, options)));

                    if (crossBrace && col > 0) {
                        bodyC = bodies[(col - 1) + ((row - 1) * columns)];
                        Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyC, bodyB: bodyB }, options)));
                    }

                    if (crossBrace && col < columns - 1) {
                        bodyC = bodies[(col + 1) + ((row - 1) * columns)];
                        Composite.addConstraint(composite, Constraint.create(Common.extend({ bodyA: bodyC, bodyB: bodyB }, options)));
                    }
                }
            }
        }

        composite.label += ' Mesh';

        return composite;
    };

    /**
     * Create a new composite containing bodies created in the callback in a pyramid arrangement.
     * This function uses the body's bounds to prevent overlaps.
     * @method pyramid
     * @param {number} x Starting position in X.
     * @param {number} y Starting position in Y.
     * @param {number} columns
     * @param {number} rows
     * @param {number} columnGap
     * @param {number} rowGap
     * @param {function} callback
     * @return {composite} A new composite containing objects created in the callback
     */
    Composites.pyramid = function(x, y, columns, rows, columnGap, rowGap, callback) {
        return Composites.stack(x, y, columns, rows, columnGap, rowGap, function(stackX, stackY, column, row, lastBody, i) {
            var actualRows = Math.min(rows, Math.ceil(columns / 2)),
                lastBodyWidth = lastBody ? lastBody.bounds.max.x - lastBody.bounds.min.x : 0;

            if (row > actualRows)
                return;

            // reverse row order
            row = actualRows - row;

            var start = row,
                end = columns - 1 - row;

            if (column < start || column > end)
                return;

            // retroactively fix the first body's position, since width was unknown
            if (i === 1) {
                Body.translate(lastBody, { x: (column + (columns % 2 === 1 ? 1 : -1)) * lastBodyWidth, y: 0 });
            }

            var xOffset = lastBody ? column * lastBodyWidth : 0;

            return callback(x + xOffset + column * columnGap, stackY, column, row, lastBody, i);
        });
    };

    /**
     * This has now moved to the [newtonsCradle example](https://github.com/liabru/matter-js/blob/master/examples/newtonsCradle.js), follow that instead as this function is deprecated here.
     * @deprecated moved to newtonsCradle example
     * @method newtonsCradle
     * @param {number} x Starting position in X.
     * @param {number} y Starting position in Y.
     * @param {number} number
     * @param {number} size
     * @param {number} length
     * @return {composite} A new composite newtonsCradle body
     */
    Composites.newtonsCradle = function(x, y, number, size, length) {
        var newtonsCradle = Composite.create({ label: 'Newtons Cradle' });

        for (var i = 0; i < number; i++) {
            var separation = 1.9,
                circle = Bodies.circle(x + i * (size * separation), y + length, size,
                    { inertia: Infinity, restitution: 1, friction: 0, frictionAir: 0.0001, slop: 1 }),
                constraint = Constraint.create({ pointA: { x: x + i * (size * separation), y: y }, bodyB: circle });

            Composite.addBody(newtonsCradle, circle);
            Composite.addConstraint(newtonsCradle, constraint);
        }

        return newtonsCradle;
    };

    /**
     * This has now moved to the [car example](https://github.com/liabru/matter-js/blob/master/examples/car.js), follow that instead as this function is deprecated here.
     * @deprecated moved to car example
     * @method car
     * @param {number} x Starting position in X.
     * @param {number} y Starting position in Y.
     * @param {number} width
     * @param {number} height
     * @param {number} wheelSize
     * @return {composite} A new composite car body
     */
    Composites.car = function(x, y, width, height, wheelSize) {
        var group = Body.nextGroup(true),
            wheelBase = 20,
            wheelAOffset = -width * 0.5 + wheelBase,
            wheelBOffset = width * 0.5 - wheelBase,
            wheelYOffset = 0;

        var car = Composite.create({ label: 'Car' }),
            body = Bodies.rectangle(x, y, width, height, {
                collisionFilter: {
                    group: group
                },
                chamfer: {
                    radius: height * 0.5
                },
                density: 0.0002
            });

        var wheelA = Bodies.circle(x + wheelAOffset, y + wheelYOffset, wheelSize, {
            collisionFilter: {
                group: group
            },
            friction: 0.8
        });

        var wheelB = Bodies.circle(x + wheelBOffset, y + wheelYOffset, wheelSize, {
            collisionFilter: {
                group: group
            },
            friction: 0.8
        });

        var axelA = Constraint.create({
            bodyB: body,
            pointB: { x: wheelAOffset, y: wheelYOffset },
            bodyA: wheelA,
            stiffness: 1,
            length: 0
        });

        var axelB = Constraint.create({
            bodyB: body,
            pointB: { x: wheelBOffset, y: wheelYOffset },
            bodyA: wheelB,
            stiffness: 1,
            length: 0
        });

        Composite.addBody(car, body);
        Composite.addBody(car, wheelA);
        Composite.addBody(car, wheelB);
        Composite.addConstraint(car, axelA);
        Composite.addConstraint(car, axelB);

        return car;
    };

    /**
     * This has now moved to the [softBody example](https://github.com/liabru/matter-js/blob/master/examples/softBody.js)
     * and the [cloth example](https://github.com/liabru/matter-js/blob/master/examples/cloth.js), follow those instead as this function is deprecated here.
     * @deprecated moved to softBody and cloth examples
     * @method softBody
     * @param {number} x Starting position in X.
     * @param {number} y Starting position in Y.
     * @param {number} columns
     * @param {number} rows
     * @param {number} columnGap
     * @param {number} rowGap
     * @param {boolean} crossBrace
     * @param {number} particleRadius
     * @param {} particleOptions
     * @param {} constraintOptions
     * @return {composite} A new composite softBody
     */
    Composites.softBody = function(x, y, columns, rows, columnGap, rowGap, crossBrace, particleRadius, particleOptions, constraintOptions) {
        particleOptions = Common.extend({ inertia: Infinity }, particleOptions);
        constraintOptions = Common.extend({ stiffness: 0.2, render: { type: 'line', anchors: false } }, constraintOptions);

        var softBody = Composites.stack(x, y, columns, rows, columnGap, rowGap, function(stackX, stackY) {
            return Bodies.circle(stackX, stackY, particleRadius, particleOptions);
        });

        Composites.mesh(softBody, columns, rows, crossBrace, constraintOptions);

        softBody.label = 'Soft Body';

        return softBody;
    };

})();