dyna3/src/dyna3.litcoffee

## A Brief Tour of dyna3

When you load dyna3, you should initially see a three-dimensional coordinate system with labeled axes.
```javascript

    import {threeLoaded,
        three as J3,
        TrackballControls as J3x} from './externals.js'

    LTx = { dashed: true, plain: false }

    buildAxis = (to, color, tx) ->
        geom = new J3.Geometry()
        if tx then mat = new J3.LineDashedMaterial(
                            {linewidth: 3, color, dashSize: 0.5, gapSize: 0.5})
        else mat = new J3.LineBasicMaterial {linewidth:3, color}
        geom.vertices.push(new J3.Vector3(0,0,0))
        geom.vertices.push to.clone()
        axis = new J3.Line geom, mat, J3.LineSegments
        axis.computeLineDistances()
        axis

    axes = (length) ->
        ax = new J3.Object3D()
        dirs = [ new J3.Vector3(length, 0, 0),
                 new J3.Vector3(0, length, 0),
                 new J3.Vector3(0, 0, length) ]
        cols = [ 0xFF0000, 0x00FF00, 0x0000FF ]
        for i in [0, 1, 2]
            ax.add buildAxis dirs[i], cols[i], LTx.plain
            dirs[i].multiplyScalar(-1)
            ax.add buildAxis dirs[i], cols[i], LTx.dashed
        ax

    main = ->
        renderer = new J3.WebGLRenderer()
        rwd = window.innerWidth
        rht = window.innerHeight
        renderer.setSize rwd, rht
        renderer.setClearColor 0xdddddd, 1.0
        document.body.appendChild renderer.domElement

        scene = new J3.Scene()
        geometry = new J3.IcosahedronBufferGeometry 1
        material = new J3.MeshPhongMaterial {color: 0xff00ff}
        ball = new J3.Mesh geometry, material
        scene.add ball
        scene.add axes 10

        ambient = new J3.HemisphereLight 0xffffff, 0xaaaaaa, 1
        ambient.position.set 0.1, 0.1, 1
        scene.add ambient

        camera = new J3.PerspectiveCamera 75, rwd/rht, 0.1, 1000
        camera.up.set 0, 0, 1
        camera.position.set 4, -1, 3

        controls = new J3x.TrackballControls camera, renderer.domElement

        renderer.setAnimationLoop ->
           controls.update()
           renderer.render scene,camera

    threeLoaded.then main
```