three-line-2d

(click to view demo)

A utility for 2D line drawing in ThreeJS, by expanding a polyline in a vertex shader for variable thickness, anti-aliasing, gradients, line dashes, and other GPU effects.

Works in ThreeJS r69-r75, and possibly newer versions.

See test/index.js for a complete example, as well as other shader applications.

var bezier = require('adaptive-bezier-curve');
var Line = require('three-line-2d')(THREE);
var BasicShader = require('three-line-2d/shaders/basic')(THREE);
 
//build a smooth bezier curve in world units
var quality = 5;
var curve = bezier([0, 0], [0.5, 1], [1, 1], [2, 0], quality);
 
//create our geometry
var curveGeometry = Line(curve);
 
//create a material using a basic shader
var mat = new THREE.ShaderMaterial(BasicShader({
    side: THREE.DoubleSide,
    diffuse: 0x5cd7ff,
    thickness: 0.3
}));
 
var mesh = new THREE.Mesh(curveGeometry, mat);
app.scene.add(mesh);

Usage

geometry = Line(path, [opt])

Creates a new Line geometry from a 2D list of points. Options:

• distances if true, each vertex will also pass a lineDistance attribute to the vertex shader. This can be used to compute the U texture coordinate from the start of the line to its end.
• closed if true, a segment will be drawn from the last point to the the first point, and the normals will be adjusted accordingly (default false)

Note: You can also omit the path and just pass an opt object to initially construct the geometry. However, some versions of ThreeJS do not support dynamically growing vertex data, so it's best to pass an initial list of points with the maximum capacity of your desired line.

geometry.update(path[, closed])

Updates the geometry with the new 2D polyline, which can optionally be a closed loop (default false).

Running from Source

git clone https://github.com/mattdesl/three-line-2d.git
cd three-line-2d
npm install

You can run the demo locally on localhost:9966 with:

npm run start

You can build the demo to a static JavaScript bundle with:

npm run build

Changelog

1.1.0

• Major code cleanup and new test with cleaner modules
• Support r69-r75
• It seems like ThreeJS does not support dynamically growing geometry across all versions; use with care!

License

MIT, see LICENSE.md for details.