Sprite not showing - three.js

Question

I have some code at https://jsfiddle.net/72mnd2yt/1/ that doesn't display the sprite I'm trying to draw. I tried to follow the code over at https://stemkoski.github.io/Three.js/Sprite-Text-Labels.html and read it line by line, but I'm not sure where I went wrong. would someone mind taking a look at it?
Here is some relevant code:
// picture
var getPicture = function(message){
var canvas = document.createElement('canvas');
canvas.width = "100%";
canvas.height = "100%";
var context = canvas.getContext('2d');
context.font = "10px";
context.fillText(message, 0, 10);
var picture = canvas.toDataURL();
// return picture;
return canvas;
};
// let there be light and so forth...
var getScene = function(){
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(
70,
$('body').width(),
$('body').height(),
1,
1000
);
var light = new THREE.PointLight(0xeeeeee);
scene.add(camera);
scene.add(light);
var renderer = new THREE.WebGLRenderer();
renderer.setClearColor(0xefefef);
renderer.setSize($('body').width(), $('body').height());
camera.position.z = -10;
camera.lookAt(new THREE.Vector3(0, 0, 0));
return [scene, renderer, camera];
};
// now for the meat
var getLabel = function(message){
var texture = new THREE.Texture(getPicture(message));
var spriteMaterial = new THREE.SpriteMaterial(
{map: texture }
);
var sprite = new THREE.Sprite(spriteMaterial);
//sprite.scale.set(100, 50, 1.0);
return sprite
};
var setup = function(){
var scene;
var renderer;
var camera;
[scene, renderer, camera] = getScene();
$('body').append(renderer.domElement);
var label = getLabel("Hello, World!");
scene.add(label);
var animate = function(){
requestAnimationFrame(animate);
renderer.render(scene, camera);
};
animate();
};
setup();

Answer 1

A few points:
1) canvas.width = "100%" should be canvas.width = "100" (canvas sizes are assumed to be px). Same with canvas.height.
2) $('body').height() is 0, so the renderer canvas is not visible (you can check this out in dev tools, it's in the element tree but squashed to 0px high). I know nothing about jQuery, so not sure why this is, but I would recommend using window.innerHeight and window.innerWidth instead anyways. So renderer.setSize(window.innerWidth, window.innerHeight). You'll also want to make this change in the camera initialization.
3) Speaking of the camera initialization, you are passing in width and height as separate arguments, when there should only be an aspect ratio argument. See the docs. So
var camera = new THREE.PerspectiveCamera(70, window.innerWidth, window.innerHeight, 1, 1000)
becomes
var camera = new THREE.PerspectiveCamera(70, window.innerWidth/window.innerHeight, 1, 1000)
4) Because textures are assumed to be static, you need to add something to this part:
var texture = new THREE.Texture(getPicture(message))
texture.needsUpdate = true // this signals that the texture has changed
That's a one-time flag, so you need to set it every time the canvas changes if you want a dynamic texture. You don't have to make a new THREE.Texture each time, just add texture.needsUpdate in the render loop (or in an event that only fires when you want the texture to change, if you're going for efficiency). See the docs, under .needsUpdate.
At this point, it should work. Here are some further things to consider:
5) Instead of using Texture you could use CanvasTexture, which sets .needsUpdate for you. The fiddle you posted is using Three.js r71, which doesn't have it, but newer versions do. That would look like this:
var texture = new THREE.CanvasTexture(getPicture(message));
// no needsUpdate necessary
6) It looks like you were on this path already based on the commented out return picture, but you can use either canvas element, or a data url generated from the canvas for a texture. If getPicture now returns a data url, try this:
var texture = new THREE.TextureLoader().load(getPicture(message))
You can also indirectly use a data url with Texture:
var img = document.createElement('img')
var img = new Image()
img.src = getPicture(message)
var texture = new THREE.Texture(img);
texture.needsUpdate = true
If not, just stick with Texture or CanvasTexture, both will take a canvas element. Texture can indirectly take a url by passing in an image element whose src is set to the data url.
Fiddle with the outlined fixes:
https://jsfiddle.net/jbjw/x0uL1kbh/