gl-mesh

Static indexed mesh drawing for WebGL

npm install gl-mesh
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gl-mesh

WebGL class for rendering static indexed geometry

Example

Try this demo in your browser

var shell = require("gl-now")()
var createMesh = require("gl-mesh")
var simple2DShader = require("simple-2d-shader")

var mesh, shader

shell.on("gl-init", function() {
  shader = simple2DShader(shell.gl)
  mesh = createMesh(shell.gl,
      [[0, 1, 2],
       [2, 1, 3]],
      { "position": [[-1,-1],   [0, 1],    [0, 0],    [1, -1]],
        "color":    [[1, 0, 0], [0, 1, 0], [0, 0, 1], [1, 1, 1]] })
})

shell.on("gl-render", function(t) {
  shader.bind()
  mesh.bind(shader)
  mesh.draw()
  mesh.unbind()
})

And here is what it should look like:

Install

Use npm to install it locally:

npm install gl-mesh

Then you can build/run the client using any tool that compiles CommonJS modules, for example browserify or beefy.

API

var createMesh = require("gl-mesh")

Constructor

var mesh = createMesh(gl, cells, attributes)

Creates a static mesh.

  • gl is a webgl context
  • cells is a list of representing indices into the geometry
  • attributes is an object of attributes to pass to the mesh

Each of these objects can be encoded as either an array-of-native-arrays or as a typed array using ndarrays. The first dimension in the shape is interepreted as the number of vertices in the attribute while the second dimension is interpreted as the size. For example, to pass in a packed array of 3d vertices in a typed array you could do:

var mesh = createMesh(gl, cells, { "positions": ndarray(position_data, [numVertices, 3]) })

The drawing mode for the mesh is determined by the shape of the cells according to the following rule:

  • cells.length == 0 : empty mesh
  • cells[0].length == 1 : gl.POINTS
  • cells[0].length == 2 : gl.LINES
  • cells[0].length == 3 : gl.TRIANGLES

You can also skip the cells parameter, in which case the resulting mesh is drawn as a point cloud.

Also you can pass a single object with a cells field. For example, here is the quickest way to create a Stanford bunny test mesh:

var bunnyMesh = createMesh(gl, require("bunny"))

Where the module comes from the bunny package

Returns A Mesh object

Methods

Each Mesh object has the following methods:

mesh.bind(shader)

Binds the mesh to the given shader updating attributes accordingly.

  • shader is an instance of a shader created using gl-shader

mesh.draw()

Draws an instance of the mesh once it is bound to a shader

mesh.unbind()

Unbinds the mesh releasing the current vertex attribute state

mesh.dispose()

Destroys the mesh and releases all of its associated resources

Credits

(c) 2013 Mikola Lysenko. MIT License

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