three.js 2D Text sprite labels

问题:

I'm new to three.js and have some issues belonging 2D Text:

What I want: I want some Labels for eg. the x,y and z-axis. The labels should always look to the camera. Maybe later they should only be shown, if their hovered but that's another topic.

What are my issues I found this tutorial (which is excatly the effect I want to achieve | http://stemkoski.github.io/Three.js/Sprite-Text-Labels.html), but it's for an old version of three.js using methods like var spriteAlignment = THREE.SpriteAlignment.topLeft;. I found this workaround (THREE.SpriteAlignment showing up as undefined) but it's not clear for me how I could use the new approach for my needs.

What I'm looking for Maybe you could help me name that thing I was searching for or come up with a short approach.

回答1:

Text Sprites are nice, but if you use more then thousand of it it can slow down everything because of the GPU.

There is a "better" way, create the Sprite as Canvas, here is a function that I use too for it:

    function makeTextSprite( message, parameters )
    {
        if ( parameters === undefined ) parameters = {};
        var fontface = parameters.hasOwnProperty("fontface") ? parameters["fontface"] : "Arial";
        var fontsize = parameters.hasOwnProperty("fontsize") ? parameters["fontsize"] : 18;
        var borderThickness = parameters.hasOwnProperty("borderThickness") ? parameters["borderThickness"] : 4;
        var borderColor = parameters.hasOwnProperty("borderColor") ?parameters["borderColor"] : { r:0, g:0, b:0, a:1.0 };
        var backgroundColor = parameters.hasOwnProperty("backgroundColor") ?parameters["backgroundColor"] : { r:255, g:255, b:255, a:1.0 };
        var textColor = parameters.hasOwnProperty("textColor") ?parameters["textColor"] : { r:0, g:0, b:0, a:1.0 };

        var canvas = document.createElement('canvas');
        var context = canvas.getContext('2d');
        context.font = "Bold " + fontsize + "px " + fontface;
        var metrics = context.measureText( message );
        var textWidth = metrics.width;

        context.fillStyle   = "rgba(" + backgroundColor.r + "," + backgroundColor.g + "," + backgroundColor.b + "," + backgroundColor.a + ")";
        context.strokeStyle = "rgba(" + borderColor.r + "," + borderColor.g + "," + borderColor.b + "," + borderColor.a + ")";

        context.lineWidth = borderThickness;
        roundRect(context, borderThickness/2, borderThickness/2, (textWidth + borderThickness) * 1.1, fontsize * 1.4 + borderThickness, 8);

        context.fillStyle = "rgba("+textColor.r+", "+textColor.g+", "+textColor.b+", 1.0)";
        context.fillText( message, borderThickness, fontsize + borderThickness);

        var texture = new THREE.Texture(canvas) 
        texture.needsUpdate = true;

        var spriteMaterial = new THREE.SpriteMaterial( { map: texture, useScreenCoordinates: false } );
        var sprite = new THREE.Sprite( spriteMaterial );
        sprite.scale.set(0.5 * fontsize, 0.25 * fontsize, 0.75 * fontsize);
        return sprite;  
    }

回答2:

I've published a module on NPM that does that for you: https://github.com/gamestdio/three-text2d

It allows you to have an Object3D with rendered text without dealing with canvas manually.

Example:

var Text2D = require('three-text2d').Text2D

var text = new Text2D("Hello world!", { align: textAlign.right, font: '30px Arial', fillStyle: '#000000', antialias: true })
scene.add(text) 

回答3:

You can use my SpriteText object. See example of using sprites_text.

Example of code:

var spriteText = new THREE.SpriteText({ text: 'Hello world!' });
scene.add( spriteText );