meshline-andrewray

THREE.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 THREE.MeshLine to plot graphs
• Spinner: example of dynamic THREE.MeshLine with texture
• SVG: example of THREE.MeshLine rendering SVG Paths
• Shape: example of THREE.MeshLine created from a mesh
• Birds: example of THREE.MeshLine.advance() by @caramelcode (Jared Sprague) and @mwcz (Michael Clayton)

How to use

• Create and populate a geometry
• Create a THREE.MeshLine and assign the geometry
• Create a THREE.MeshLineMaterial
• Use THREE.MeshLine and THREE.MeshLineMaterial to create a THREE.Mesh

Create and populate a geometry

First, create the list of vertices that will define the line. THREE.MeshLine accepts THREE.Geometry (looking up the .vertices in it) and Array/Float32Array. THREE.BufferGeometry coming soon, and may be others like Array of THREE.Vector3.

var geometry = new THREE.Geometry();
for( var j = 0; j < Math.PI; j += 2 * Math.PI / 100 ) {
    var v = new THREE.Vector3( Math.cos( j ), Math.sin( j ), 0 );
    geometry.vertices.push( v );
}

Create a THREE.MeshLine and assign the geometry

Once you have that, you can create a new THREE.MeshLine, and call .setGeometry() passing the vertices.

var line = new THREE.MeshLine();
line.setGeometry( geometry );

Note: .setGeometry 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.

line.setGeometry( geometry, function( p ) { return 2; } ); // makes width 2 * lineWidth
line.setGeometry( geometry, function( p ) { return 1 - p; } ); // makes width taper
line.setGeometry( geometry, function( p ) { return 2 + Math.sin( 50 * p ); } ); // makes width sinusoidal

Create a THREE.MeshLineMaterial

A THREE.MeshLine needs a THREE.MeshLineMaterial:

var material = new THREE.MeshLineMaterial();

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

THREE.MeshLineMaterial has several attributes to control the appereance of the THREE.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)
• 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 - THREE.Vector2 to define the dashing (NOT IMPLEMENTED YET)
• 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)
• near - camera near clip plane distance (REQUIRED if sizeAttenuation set to false)
• far - camera far clip plane distance (REQUIRED if sizeAttenuation set to false)

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 THREE.MeshLine and THREE.MeshLineMaterial to create a THREE.Mesh

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

var mesh = new THREE.Mesh( line.geometry, material ); // this syntax could definitely be improved!
scene.add( mesh );

TODO

• Better miters
• Proper sizes
• Support for dashArray

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 Jaume Sanchez Elias, http://www.clicktorelease.com