javascript - Three JS Projection Issue -

i trying @ polygon's center in 3d space convert points 2d screen coordinates. code doesn't work. appreciated.

//calculate center var center = new three.vector3(); (var = 0; < positions.length; i++) {     center.add(positions[i]); } center.multiplyscalar(1 / positions.length); //look @ center var camera = new three.perspectivecamera(75, width / height, 0.1, 1000); camera.lookat(center); //calculate screen coordinates (var = 0; < positions.length; i++) {     screenpositions.push(toscreenxy(positions[i], camera, width, height)); }  function toscreenxy(position, camera, width, height) {     var pos = position.clone();     pos.project(camera);     var halfwidth = width / 2,         halfheight = height / 2;     return {         x: (pos.x + 1) * halfwidth + halfwidth,         y: (-pos.y + 1) * halfheight + halfheight     };  } 

it though camera transformations have no effect on projection

since changed camera's rotation, need update camera's world matrix, because method project() references it.

camera.position.set( x, y, z ); camera.lookat( center );  camera.updatematrixworld(); // add 

the renderer calls camera.updatematrixworld() in renderer.render(), in case, have call yourself.

three.js r.71