draw-billboard

draw-billboard

Draws a 2D billboarded sprite in WebGL. Useful for debugging and small special effects.

Example

var shell = require("gl-now")()
var camera = require("game-shell-orbit-camera")(shell)
var renderText = require("gl-render-text")
var drawBillboard = require("draw-billboard")
var mat4 = require("gl-matrix").mat4

var texture
var positions = new Array(100)

shell.on("gl-init", function() {
  var gl = shell.gl
  texture = renderText(gl, "Billboard")
  
  for(var i=0; i<100; ++i) {
    positions[i] = [ 100 * (0.5 - Math.random()),
                     100 * (0.5 - Math.random()),
                     100 * (0.5 - Math.random()) ]
  }
})

shell.on("gl-render", function() {
  var proj = mat4.perspective(mat4.create(), Math.PI/4.0, shell.width/shell.height, 0.1, 1000.0)
  var view = camera.view()
  for(var i=0; i<100; ++i) {
    drawBillboard(shell.gl, positions[i], { texture: texture, projection: proj, view: view })
  }
})

Try it in your browser.

Install

npm install draw-billboard

API

require("draw-billboard")(gl, position[, options])

Draws a billboard at the given position.

• gl is a WebGL context
• positions is the position of the billboarded sprite
• options is an object containing the following properties:
  • texture A WebGL texture object
  • lo Lower texture coordinate
  • hi Upper texture coordiante
  • width Width of billboard to draw
  • height Height of billboard to draw
  • model Model matrix for billboard
  • view View matrix for billboard
  • projection Projection matrix for billboard

Credits

(c) 2013 Mikola Lysenko. MIT License