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In-Reply-To: <9303060020.AA38966@doorstop.austin.ibm.com>; from "Paul Chamberlain" at Mar 5, 93 6:20 pm
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From: "Michael Schroeder (Inf4 - hiwi)" <immd4.informatik.uni-erlangen.de!mlschroe>
To: cs.Princeton.EDU!rayshade-users
Subject: Re: deformed donuts

> 
> Could someone run this through their version of rayshade and
> confirm that it looks right on theirs before I go digging to
> see why my version is screwing up.
> 
> 	fov 5 torus 0.25 0.21 0 0 0 0 1 0

It looks good with my rayshade version. Of course I have patched
roots.c a little bit to make SolveCubic more stable (had the
same problems a while ago).

You can also fix the problem by defining a bigger torus and scaling
it down.

Michael.

---------------------------------------------------------------
Michael Schroeder    mlschroe@faui43.informatik.uni-erlangen.de
main(a){while(a=~getchar())putchar(~a-1/(~(a|32)/13*2-11)*13);}

*** roots.c.orig	Sat Mar  6 17:06:43 1993
--- roots.c	Sat Jul 11 20:10:07 1992
***************
*** 39,44 ****
--- 39,45 ----
  
  #define     EQN_EPS     1e-9
  #define	    IsZero(x)	((x) > -EQN_EPS && (x) < EQN_EPS)
+ #define	    IsZero2(x)	((x) > -EQN_EPS*EQN_EPS && (x) < EQN_EPS*EQN_EPS)
  
  #ifndef CBRT
  #define     cbrt(x)     ((x) > 0.0 ? pow((double)(x), 1.0/3.0) : \
***************
*** 105,111 ****
      cb_p = p * p * p;
      D = q * q + cb_p;
  
!     if (IsZero(D))
      {
  	if (IsZero(q)) /* one triple solution */
  	{
--- 106,112 ----
      cb_p = p * p * p;
      D = q * q + cb_p;
  
!     if (IsZero2(D))
      {
  	if (IsZero(q)) /* one triple solution */
  	{

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