Trandforming a 3D point to the 2D screen given the view direction

I have a DXF file that I want to render onto the screen as an orthographic 2D image. The view direction vector is given in the following format: -0.720495631362985, -1.49503251161485, 0.495745735636187 I want to translate a point onto the screen, given the x, y and z coordinates in the form screen-x, screen-y. Google mostly delivers opengl solutions. If the View direction is looking straight down (ie. the z-coordinate is removed), then the vector is as follows: 0,0,1 In which case ((int)x, (int)y)==(screen-x,screen-y) I have asked this question before, but it would seem that that was before the board was upgraded.