three.meshline

MeshLine

Mesh replacement for THREE.Line

Instead of using GL_LINE, it uses a strip of triangles billboarded. Some examples:

• Demo: play with the different settings of materials
• Graph: example of using MeshLine to plot graphs
• Spinner: example of dynamic MeshLine with texture
• SVG: example of MeshLine rendering SVG Paths
• Shape: example of MeshLine created from a mesh
• Birds: example of MeshLine.advance() by @caramelcode (Jared Sprague) and @mwcz (Michael Clayton)

How to use

• Include script
• Create an array of 3D coordinates
• Create a MeshLine and assign the points
• Create a MeshLineMaterial
• Use MeshLine and MeshLineMaterial to create a THREE.Mesh

Include the script

Include script after THREE is included

<script src="THREE.MeshLine.js"></script>

or use npm to install it

npm i three.meshline

and include it in your code (don't forget to require three.js)

const THREE = require('three');
const MeshLine = require('three.meshline').MeshLine;
const MeshLineMaterial = require('three.meshline').MeshLineMaterial;
const MeshLineRaycast = require('three.meshline').MeshLineRaycast;

or

import * as THREE from 'three';
import { MeshLine, MeshLineMaterial, MeshLineRaycast } from 'three.meshline';

Create an array of 3D coordinates

First, create the list of numbers that will define the 3D points for the line.

const points = [];
for (let j = 0; j < Math.PI; j += (2 * Math.PI) / 100) {
  points.push(Math.cos(j), Math.sin(j), 0);
}

MeshLine also accepts a BufferGeometry looking up the vertices in it.

const points = [];
for (let j = 0; j < Math.PI; j += 2 * Math.PI / 100) {
  points.push(new THREE.Vector3(Math.cos(j), Math.sin(j), 0));
}
const geometry = new THREE.BufferGeometry().setFromPoints(points);
const line = new MeshLine();
line.setGeometry(geometry);

Create a MeshLine and assign the points

Once you have that, you can create a new MeshLine, and call .setPoints() passing the list of points.

const line = new MeshLine();
line.setPoints(points);

Note: .setPoints accepts a second parameter, which is a function to define the width in each point along the line. By default that value is 1, making the line width 1 * lineWidth in the material.

// p is a decimal percentage of the number of points
// ie. point 200 of 250 points, p = 0.8
line.setPoints(geometry, p => 2); // makes width 2 * lineWidth
line.setPoints(geometry, p => 1 - p); // makes width taper
line.setPoints(geometry, p => 2 + Math.sin(50 * p)); // makes width sinusoidal

Create a MeshLineMaterial

A MeshLine needs a MeshLineMaterial:

const material = new MeshLineMaterial(OPTIONS);

By default it's a white material of width 1 unit.

MeshLineMaterial has several attributes to control the appereance of the MeshLine:

• map - a THREE.Texture to paint along the line (requires useMap set to true)
• useMap - tells the material to use map (0 - solid color, 1 use texture)
• alphaMap - a THREE.Texture to use as alpha along the line (requires useAlphaMap set to true)
• useAlphaMap - tells the material to use alphaMap (0 - no alpha, 1 modulate alpha)
• repeat - THREE.Vector2 to define the texture tiling (applies to map and alphaMap - MIGHT CHANGE IN THE FUTURE)
• color - THREE.Color to paint the line width, or tint the texture with
• opacity - alpha value from 0 to 1 (requires transparent set to true)
• alphaTest - cutoff value from 0 to 1
• dashArray - the length and space between dashes. (0 - no dash)
• dashOffset - defines the location where the dash will begin. Ideal to animate the line.
• dashRatio - defines the ratio between that is visible or not (0 - more visible, 1 - more invisible).
• resolution - THREE.Vector2 specifying the canvas size (REQUIRED)
• sizeAttenuation - makes the line width constant regardless distance (1 unit is 1px on screen) (0 - attenuate, 1 - don't attenuate)
• lineWidth - float defining width (if sizeAttenuation is true, it's world units; else is screen pixels)

If you're rendering transparent lines or using a texture with alpha map, you should set depthTest to false, transparent to true and blending to an appropriate blending mode, or use alphaTest.

Use MeshLine and MeshLineMaterial to create a THREE.Mesh

Finally, we create a mesh and add it to the scene:

const mesh = new THREE.Mesh(line, material);
scene.add(mesh);

You can optionally add raycast support with the following.

mesh.raycast = MeshLineRaycast;

Declarative use

THREE.meshline can be used declaritively. This is how it would look like in react-three-fiber. You can try it live here.

import { extend, Canvas } from 'react-three-fiber'
import { MeshLine, MeshLineMaterial, MeshLineRaycast } from 'three.meshline'

extend({ MeshLine, MeshLineMaterial })

function Line({ points, width, color }) {
  return (
    <Canvas>
      <mesh raycast={MeshLineRaycast}>
        <meshLine attach="geometry" points={points} />
        <meshLineMaterial
          attach="material"
          transparent
          depthTest={false}
          lineWidth={width}
          color={color}
          dashArray={0.05}
          dashRatio={0.95}
        />
      </mesh>
    </Canvas>
  )
}

Dynamic line widths can be set along each point using the widthCallback prop.

<meshLine attach='geometry' points={points} widthCallback={pointWidth => pointWidth * Math.random()} />

TODO

• Better miters
• Proper sizes

Support

Tested successfully on

• Chrome OSX, Windows, Android
• Firefox OSX, Windows, Anroid
• Safari OSX, iOS
• Internet Explorer 11 (SVG and Shape demo won't work because they use Promises)
• Opera OSX, Windows

References

• Drawing lines is hard
• WebGL rendering of solid trails
• Drawing Antialiased Lines with OpenGL

License

MIT licensed

Copyright (C) 2015-2016 Jaume Sanchez Elias, http://www.clicktorelease.com