Assign UVs in three.js.

gistfile1.js

function assignUVs( geometry ) {

  geometry.computeBoundingBox();
  var max     = geometry.boundingBox.max;
  var min     = geometry.boundingBox.min;
  var offset  = new THREE.Vector2(0 - min.x, 0 - min.y);
  var range   = new THREE.Vector2(max.x - min.x, max.y - min.y);
  var faces = geometry.faces;

  geometry.faceVertexUvs[0] = [];
  for (i = 0; i < geometry.faces.length ; i++) {
    var v1 = geometry.vertices[ faces[i].a ];
    var v2 = geometry.vertices[ faces[i].b ];
    var v3 = geometry.vertices[ faces[i].c ];
    geometry.faceVertexUvs[0].push([
      new THREE.Vector2( ( v1.x + offset.x ) / range.x , ( v1.y + offset.y ) / range.y ),
      new THREE.Vector2( ( v2.x + offset.x ) / range.x , ( v2.y + offset.y ) / range.y ),
      new THREE.Vector2( ( v3.x + offset.x ) / range.x , ( v3.y + offset.y ) / range.y )
    ]);
  }

  geometry.uvsNeedUpdate = true;
}