Animating Canvas Billboard in THREE.js

Question

Everyone,

I'm trying to animate a Canvas-based texture that is mapped onto a plane, like a billboard. I've made a point of including material.needsUpdate & texture.needsUpdate, but I'm still unable to get the texture to come to life. I've also included a rotating cube just so I know the animation routine is functioning on some level.

Here is the code:


    
      
      
        if ( window.innerWidth === 0 ) { window.innerWidth = parent.innerWidth; window.innerHeight = parent.innerHeight; }

            var camera, scene, renderer;
            var mesh, geometry, material;
            var light, sign, animTex;
            var canvas, context;

            init();
            animate();

            function init() {

                camera = new THREE.PerspectiveCamera( 50, window.innerWidth / window.innerHeight, 1, 1200 );
                camera.position.z = 700;

                scene = new THREE.Scene();

                material = new THREE.MeshLambertMaterial(
                    { color: 0x885522
                    , wireframe: false
                     , overdraw: false
                    } );
                geometry = new THREE.CubeGeometry( 80, 120, 100, 1,1,1);
                mesh = new THREE.Mesh( geometry, material );

                sign = createSign();

                light = new THREE.DirectionalLight(0xFFFFFF, 3.0);
                light.position = new THREE.Vector3(5,10,7);
                light.target = new THREE.Vector3(0,0,0);

                scene.add( mesh );
                scene.add( sign );
                scene.add( light );

                renderer = new THREE.CanvasRenderer();
                renderer.setSize( window.innerWidth, window.innerHeight );
                document.body.appendChild( renderer.domElement );

            }
            function createSign() {
                canvas = document.createElement("canvas");
                context = canvas.getContext("2d");
                canvas.width = 200;
                canvas.height = 200;
                context = canvas.getContext("2d");              
                var texture = new THREE.Texture(canvas);
                texture.needsUpdate = true;
                var material = new THREE.MeshBasicMaterial({ map : texture, overdraw: true });
                material.needsUpdate = true;
                var mesh = new THREE.Mesh(new THREE.PlaneGeometry(200, 200), material);
                mesh.doubleSided = true;
                return mesh;
            }

            function animate() {

                var time = Date.now()*0.01;
                var sinTime = Math.sin ( time * 0.05 ) * 100;
                var cosTime = Math.cos ( time * 0.05 ) * 100;

                mesh.rotation.y = sinTime*0.01;

                requestAnimationFrame( animate );
                context.fillStyle="black";
                context.fillRect(0,0,canvas.width,canvas.height);
                context.fillStyle="white";
                context.fillRect ( (canvas.width/2) + sinTime, (canvas.height/2) + cosTime, 20, 20 )
                renderer.render( scene, camera );
            }

This runs, but I can't seem to get the Canvas texture material to update. What have I overlooked? Thanks very much for any pointers!

WestLangley WestLangley · Accepted Answer · 2012-09-16T21:24:19

Place this right before your render() call:

sign.material.map.needsUpdate = true;

Fiddle: http://jsfiddle.net/pPKVa/

Animating Canvas Billboard in THREE.js

2 Answers