text: //Code for setting up shader program is provided for you
  var setupShader  = require('./setup-shader')
  var drawTriangle = require('./draw-triangle')
  
  var scales  = [ 0.15, 0.25, 0.5, 0.3 ]
  var offsets = [ [-0.5,-0.5], 
                  [0.5,-0.5], 
                  [0.1,0.3],
                  [0.3,-0.4] ]
  var colors  = [ [1, 0, 0],
                  [0, 1, 0],
                  [0, 0, 1],
                  [1, 1, 0] ]
  
  var program
  var uScale, uOffset, uColor
  
  exports.init = function(gl) {
    program = setupShader(gl)
  
    uScale  = gl.getUniformLocation(program, 'scale')
    uOffset = gl.getUniformLocation(program, 'offset')
    uColor  = gl.getUniformLocation(program, 'color')
  }
  
  exports.draw = function(gl) {
    gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight)
    gl.clearColor(0,0,0,1)
    gl.clear(gl.COLOR_BUFFER_BIT)
  
    gl.useProgram(program)
  
    for(var i=0; i<4; ++i) {
      gl.uniform1f(uScale, scales[i])
      gl.uniform2fv(uOffset, offsets[i])
      gl.uniform3fv(uColor, colors[i])
      drawTriangle(gl)
    }
  }