title: draw sprite on where mouse clicked
body: <p>I am noobie to three.js, after reading <a href="https://threejs.org/examples/?q=inter#canvas_interactive_cubes" rel="nofollow">https://threejs.org/examples/?q=inter#canvas_interactive_cubes</a> , I want to add a function draw points where i clicked to my project(load and display stl files), I used the formula in that example, </p>
  
  <pre><code>mouse.x = ( event.clientX / renderer.domElement.clientWidth ) * 2 - 1;
  mouse.y = - ( event.clientY / renderer.domElement.clientHeight ) * 2 + 1;
  </code></pre>
  
  <p>but I found when the sprite is not drawn on where i clicked, but a little lower, you can see at <a href="http://static.medi-tool.cn/share/ds1/index.html" rel="nofollow">http://static.medi-tool.cn/share/ds1/index.html</a> (first click on the model will draw a sprite, second will draw a sprite and calculate the distance between two point, then two sprite will be removed in 2 seconds). can anyone tell me why? thanks a lot.</p>