Path: chuka.playstation.co.uk!news From: Jake Turner Newsgroups: scee.yaroze.programming.3d_graphics Subject: Re: Push me! Date: Sun, 01 Nov 1998 21:42:45 +0000 Organization: PlayStation Net Yaroze (SCEE) Lines: 39 Message-ID: <363CD5D5.2B1A46F9@cthullu.freeserve.co.uk> References: <363CBFF3.5A67B9B5@ndirect.co.uk> NNTP-Posting-Host: 212.56.112.150 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 4.05 [en] (Win95; I) Alex Herbert wrote: > Maybe I'm being a little thick here, but I don't get the PushMatrix and > PopMatrix functions. The Library Reference says "PushMatrix evacuates > the rotation matrix to the stack", but which rotation matrix? > PushMatrix/PopMatrix take no arguments and this leaves me a little > confused. I've also noticed that some of the Matrix functions say that > "the rotation matrix is fragmented" - whatever that means. I'm guessing > that the two things are related, and that PushMatrix and PopMatrix are > used to save and restore the rotation matrix which gets "fragmented". > Am I right? Either way, could someone explain. > Good old Japanese corruption of the English language ! pushmatrix, popmatrix are just like in OpenGL where you can save the current rotation & translation matrix. So on NY you can push/pop the current GTE rotation matrix onto a putative stack (the scratch pad if I remember correctly). The fragmented is a polite way of saying destroyed. So you are correct you can use push/pop matrix to save and restore the rotation matrix before/after the functions that corrupt the rotation matrix. The "rotation" matrix means the currently set GTE matrix that is used for all the hardware 3D co-ordinate transformations (matrix multiplications). I hope this helps. -- Jake Turner : Token Rocket Scientist ========================================= Practice VI it may save your life one day Home e-mail: jaket@cthullu.freeserve.co.uk Work e-mail: jaket@revolution.co.uk