Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ucsd!nprdc!malloy
From: malloy@nprdc.arpa (Sean Malloy)
Newsgroups: comp.graphics
Subject: Re: Pixar's noise function
Keywords: random numbers, Byte, elephants
Message-ID: <1771@skinner.nprdc.arpa>
Date: 15 Apr 89 21:58:13 GMT
References: <2553@ssc-vax.UUCP> <3599@pixar.UUCP> <97699@sun.Eng.Sun.COM> <1592@ccncsu.ColoState.EDU> <43327@tut.cis.ohio-state.edu> <1648@ccncsu.ColoState.EDU>
Reply-To: malloy@nprdc.arpa (Sean Malloy)
Organization: Navy Personnel R&D Center, San Diego
Lines: 27

In article <1648@ccncsu.ColoState.EDU> bullerj@handel.colostate.edu.UUCP (Jon Buller) writes:
|In article <43327@tut.cis.ohio-state.edu> william r dirks <dirks@cis.ohio-state.edu> writes:
|>On a hunch I changed all the trunc()'s in the source to floor()'s.
|>
|>And presto!! Continuous bumps everywhere!
|
|    I wish I could do that, my compiler doesn't have a built in Floor,
|and I haven't had the time to hack one up from the Mac toolbox and SANE
|(IEEE math pkg) calls, oh well, I'll have to settle for only using 
|X, Y, and Z >= 0.0

If I understand the problem correctly, writing a floor() function is
extremely simple:

int floor(x)
double x;
{
  if (x >= 0.0) return(trunc(x));
           else return(trunc(x)+1);
}


 Sean Malloy					| "The proton absorbs a photon
 Navy Personnel Research & Development Center	| and emits two morons, a
 San Diego, CA 92152-6800			| lepton, a boson, and a
 malloy@nprdc.navy.mil				| boson's mate. Why did I ever
						| take high-energy physics?"