MatterJS-with-Phaser (loss of energy)

See: https://github.com/liabru/matter-js/issues/256

by Jeroen Heijmans

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/phaser/3.55.2/phaser.min.js"></script>
<div id="phaser-example" />

JavaScript

class Example extends Phaser.Scene
{
    maxY = 0;
    minY = 400;
    lastY = 0;
    duration = 0;
    prevDuration = 0;

    create () {       
        this.logo = this.matter.add.rectangle(400, 100, 40, 10, {
            inertia: Infinity,
            restitution: 1,
            friction: 0,
            frictionAir: 0,
            frictionStatic: 0,
            slop: 0.5,
        });

        this.lastY = this.logo.position.y;
        this.text = this.add.text(10, 10, '', { font: '16px Courier', fill: '#00ff00' });
    }

    update (time, delta) {
        this.text.setText([
            'this.duration: ' + this.prevDuration,
            'last y: ' + this.lastY,
            'min y: ' + this.minY,
            'max y: ' + this.maxY
        ]);

        if (Phaser.Math.Fuzzy.LessThan(this.logo.velocity.y, 0, 0.1)) {
            this.direction = 'up';
        } else {
            this.direction = 'down';
        }

				console.log(this.logo);
        var y = this.logo.bounds.min.y;
        
        if (this.prevDirection !== this.direction && this.prevDirection === 'up') {
            var marker = this.add.line(400, y, 0, y, 500, y, 0x55ff0000);
            this.lastY = y;
            this.prevDuration = this.duration;
            this.duration = 0;
        }

        this.prevDirection = this.direction;
        this.duration += delta;

        this.minY = Math.min(this.minY, y);
        this.maxY = Math.max(this.minY, this.maxY, this.lastY);
    }
}

const config = {
    type: Phaser.AUTO,
    width: 800,
    height: 600,
    parent: 'phaser-example',
    physics: {
        default: 'matter',
        matter: {
            debug: true,
            setBounds: true,
            restingThresh: 0.001,
            positionIterations: 30,
            velocityIterations: 25,
            constraintIterations: 18,
            runner: {
                isFixed: true,
                fps: 240,
                correction: 10,
            },
            gravity: { y: 2 }
     ...