Path: chuka.playstation.co.uk!news From: daniel@reichardt.ch (Daniel Hartmeier) Newsgroups: scee.yaroze.programming.3d_graphics Subject: 3d world clipping Date: Fri, 20 Nov 1998 09:18:12 GMT Organization: Reichardt Informatik AG Lines: 32 Message-ID: <36552f4a.6753350@news.playstation.co.uk> NNTP-Posting-Host: empty223.magnet.ch Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Newsreader: Forte Agent 1.5/32.451 Hello fellows, assume that I have a world with many polygons, too many to draw them all each frame. Most of them are, however, invisible (due to the camera position, direction, etc.). What are the possibilities to reduce the number of polygons to draw? For example, I could write a function that decides for each polygon (or complex object), whether it is visible or not. I can imagine different levels of precision (bounding boxes, etc.). But of course, to evaluate such a function for each object also costs time. Is it worth it? Or is it cheaper (regarding execution time) to just let the PlayStation draw each object? Surely there are existing algorithms for this problem. Can you recommend a book, where I can look them up? Say I have a landscape consisting of 10'000 x 10'000 small tiles. What algorithms exist to reduce the number of tiles to draw. I have the camera position (x, y, z), the direction and zoom factor (x, y, z). Each tile has a position (x, y, z) and bounding box/sphere. The visible part builds a slice of a sphere (don't know the correct math expression in english :). The algorithm would determine for each object, whether it intersects with this area. I could write this straight mathematically correct, but it would be too slow, I guess. So, what level of abstraction/optimization is advisable? Regards, -- Daniel Hartmeier PGP 6A3A7409 ICQ# 12742482 "The woods are lovely, dark and deep. But I have promises to keep, And lines to code before I sleep, And lines to code before I sleep."