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From: toddh@megatek.UUCP (Todd Heckel)
Newsgroups: comp.graphics
Subject: Re: checking whether 2 2D polygons overlap
Message-ID: <850@portnoy.megatek.uucp>
Date: 8 Dec 90 22:30:34 GMT
References: <7039@plains.NoDak.edu>
Organization: Megatek Corporation, San Diego, Ca.
Lines: 26

From article <7039@plains.NoDak.edu>, by bakke@plains.NoDak.edu (Jeff Bakke):
> 
> Correct me if I'm wrong but from what I understand the Z-Buffer method,
> is the method most implemented in High performance hardware graphics
> implementation.  On the hardware level it would seem to be very efficient
> and easy to implement.  I agree that on a software level, it would be 
> stupid to fully implement a z-buffer method of hl removal but I made the
> assumption that if you were to do a software method, you would make
> adjustments and changes to the generalized algorithm to decrease unnecesary
> calculation and overlap.
> 
	I'm sorry, I didn't mean to imply that it would be stupid to use
	the algorithm in a high-performance system.  And while it is very
	easy to implement, it is NOT efficient.  Just the depth storage
	for a floating-point implementation requires well over 4 megabytes
	of high-speed RAM!  Also, like I said originally, a lot of processing
	may end up being wasted on pixels that end up being occluded anyway.
	You're correct when you state that the Z-Buffer method is the most
	implemented in high-performance graphics ___Workstations___.
	However, it is very uncommon to see Z-Buffers used in high-performance
	___Image Generators___, like those used for Flight Simulators and such.
-- 
	Todd Heckel
	Megatek Corporation	uunet!megatek!toddh	
	9645 Scranton Road		or
	San Diego, CA  92121	toddh@megatek.uucp