Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!purdue!iuvax!rutgers!neptune.rutgers.edu!jove.rutgers.edu!dmz From: dmz@jove.rutgers.edu (Dave Zirl) Newsgroups: comp.sys.sgi Subject: transforming from screen to object coordinates Message-ID: Date: 3 Jul 90 21:36:56 GMT Organization: Rutgers Univ., New Brunswick, N.J. Lines: 33 This may sound quite simple, but we are having problems none-the-less. We want to pick a point on the screen(x,y) and convert them into object(world) coordinates(X,Y,Z). The problem seems to be in the multiple layers of transformations that the screen coordinates must undergo before they become object coordinates. According to the graphics library program guide the following transformations are involved(in either direction (obect <-->screen)) obect coords --> model/view matrix --> eye coords --> projection matrix --> clip coords --> divide by w normalized coords --> viewport system --> window coords --> window offset --> screen coords -->pixel However, the problem lies in converting pixel values returned from MOUSEX and MOUSEY into the eye coordinate system and subsequently going from the eye to object coordinate system. If anyone has done any similar programming their assistance on this problem would be greatly appreciated. I can be reached at dmz@rutile.rutgers.edu Thanks in advance David Zirl Rutgers University Department of Ceramics PO Box 909 Piscataway, NJ 08855-0909 201-932-3083 dmz@rutile.rutgers.edu