manual/examples/debug-js-clearing-logger.html

<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Debug - Clearing Logger</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    #debug {
      position: absolute;
      left: 1em;
      top: 1em;
      padding: 1em;
      background: rgba(0, 0, 0, 0.9);
      color: white;
      font-family: monospace;
      pointer-events: none;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
    <div id="debug">
      <pre></pre>
    </div>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js"
  }
}
</script>

<script type="module">
import * as THREE from 'three';

class ClearingLogger {

	constructor( elem ) {

		this.elem = elem;
		this.lines = [];

	}
	log( ...args ) {

		this.lines.push( [ ...args ].join( ' ' ) );

	}
	render() {

		this.elem.textContent = this.lines.join( '\n' );
		this.lines = [];

	}

}

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 50;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.z = 20;

	const scene = new THREE.Scene();
	scene.background = new THREE.Color( 'cyan' );

	const geometry = new THREE.SphereGeometry();
	const material = new THREE.MeshBasicMaterial( { color: 'red' } );

	const things = [];

	function rand( min, max ) {

		if ( max === undefined ) {

			max = min;
			min = 0;

		}

		return Math.random() * ( max - min ) + min;

	}

	function createThing() {

		const mesh = new THREE.Mesh( geometry, material );
		scene.add( mesh );
		things.push( {
			mesh,
			timer: 2,
			velocity: new THREE.Vector3( rand( - 5, 5 ), rand( - 5, 5 ), rand( - 5, 5 ) ),
		} );

	}

	canvas.addEventListener( 'click', createThing );

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	const logger = new ClearingLogger( document.querySelector( '#debug pre' ) );

	let then = 0;
	function render( now ) {

		now *= 0.001; // convert to seconds
		const deltaTime = now - then;
		then = now;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		logger.log( 'fps:', ( 1 / deltaTime ).toFixed( 1 ) );
		logger.log( 'num things:', things.length );
		for ( let i = 0; i < things.length; ) {

			const thing = things[ i ];
			const mesh = thing.mesh;
			const pos = mesh.position;
			logger.log(
				'timer:', thing.timer.toFixed( 3 ),
				'pos:', pos.x.toFixed( 3 ), pos.y.toFixed( 3 ), pos.z.toFixed( 3 ) );
			thing.timer -= deltaTime;
			if ( thing.timer <= 0 ) {

				// remove this thing. Note we don't advance `i`
				things.splice( i, 1 );
				scene.remove( mesh );

			} else {

				mesh.position.addScaledVector( thing.velocity, deltaTime );
				++ i;

			}

		}

		renderer.render( scene, camera );
		logger.render();

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>