gl-spikes

gl-spikes ========= Draws axis spikes compatible with gl-axes. This can be useful to illustrate selections or specific points in a point cloud

gl-spikes

Draws axis spikes compatible with gl-axes. This can be useful to illustrate selections or specific points in a point cloud

Try it out here

var shell = require("gl-now")({ clearColor: [0,0,0,0], tickRate: 5 })
var camera = require("game-shell-orbit-camera")(shell)
var mat4 = require("gl-matrix").mat4
var createAxes = require("gl-axes")
var createSpikes = require("gl-spikes")
 
//Bounds on function to plot 
var bounds = [[-1,-1,-1], [1,1,1]]
 
//camera.lookAt([-15,20,-15], [0,0,0], [0, 1, 0]) 
camera.lookAt([2, 2, 2], [0,0,0], [0,1,0])
 
//State variables 
var axes, spikes
 
shell.on("gl-init", function() {
  var gl = shell.gl
  
  axes = createAxes(gl, {
    bounds: bounds,
    tickSpacing: [0.1,0.1,0.1],
    textSize: 0.05
  })
 
  spikes = createSpikes(gl, {
    bounds: bounds,
    colors: [[1,0,0,1], [0,1,0,1], [0,0,1,1]],
    position: [0,0,0]
  })
})
 
shell.on("gl-render", function() {
  var gl = shell.gl
  gl.enable(gl.DEPTH_TEST)
 
  //Compute camera parameters 
  var cameraParameters = {
    view: camera.view(),
    projection: mat4.perspective(
        mat4.create(),
        Math.PI/4.0,
        shell.width/shell.height,
        0.1,
        1000.0)
  }
 
 
  //Update spike position 
  var t = 0.001*Date.now()
  spikes.position = [Math.cos(t), Math.sin(t), Math.cos(2*t+0.1)]
 
  //Draw objects 
  axes.draw(cameraParameters)
  spikes.draw(cameraParameters)
})
npm install gl-spikes

Creates a new spike object.

  • gl is a WebGL context
  • options is a list of optional parameters which are passed along

Draws the axis spikes using the given camera coordinates.

  • camera.model is the model matrix for the camera
  • camera.view is the view matrix
  • camera.projection is the projection matrix

Updates the parameters of the axes spikes. options is an object with the following properties:

  • position the position of the spike ball in data coordinates
  • bounds the bounds of the axes object
  • colors an array of 3 length 4 arrays encoding the RGBA colors for the spikes along the x/y/z directions
  • enabled an array of 3 flags which if set turns on or off the spikes
  • drawSides an array of 3 flag which if set turns on or off the projected spikes in each data plane
  • lineWidth an array of 3 numbers giving the thickness of the spikes for each axis

Destroys the spike object and releases all associated resources.

(c) 2014 Mikola Lysenko. MIT License