three.js mouse drawing at a coplanar distance from camera
<p>I am creating an open sourced 3d "doodler".  It toggles between free-hand drawing and drawing at the intersection of previous line segments (indicated by a plane facing the camera/orbit control projection).</p>

<p>if the camera is at world position 5,0,5 and the plane is at 2,0,2,  how do i tell the mouse that at any point while drawing (mouse down), it should draw itself along the plane?  I am not doing offset handling correctly and would appreciate some guidance.  thank you!</p>