ROS3D.makeColorMaterial = function(r, g, b, a) {
  var color = new THREE.Color();
  color.setRGB(r, g, b);
  if (a <= 0.99) {
    return new THREE.MeshPhongMaterial({
      color : 0x000000,
      specular : 0x666666,
      emissive : 0x000000,
      shininess : 10,
      shading: THREE.FlatShading,
      opacity : a,
      transparent : true,
      depthWrite : false,
      depthTest : true,
      //polygonOffset : true,
      //polygonOffsetUnits : -1,
      //side : THREE.DoubleSide
    });

  } else {
    return new THREE.MeshPhongMaterial({
      color : 0x000000,
      opacity : a,
      blending : THREE.NormalBlending
    });
  }
};