Hi, I seem to be getting Coincidence serface 
 problem with an object and a difference.

The cylinder is leaving traces behind at the rotation of 230, but if
rotated at 270 then the traces disapear, at 210 they are there, but less
visiable.

Any pointers to whats happening?

#local drive = union
{
	difference
	{
		lathe
		{
			cubic_spline
			11 <0,0>,<4,0>,<6,1>,<7.3,4>,<7,5.7>,<6,6.3>,<7,7.2>,<5,8>,<4,7>,<4,0>,<0,0>
			texture 
			{ 
				Cowling
			}
			rotate <0,0,-90>
		}
		cylinder 
		{
			<1,0,0> <7,0,0> 4.35
			texture 
			{	 
				PropGear
			}
		}
	}
	torus
	{
		6.6,0.7
		rotate <0,0,90>
		translate <6.3,0,0>
		texture 
		{ 
			MountRings
		}
	}
}

#declare deep1 = union
{
	object {drive rotate <0,-230,0>}
}

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Try adding the keyword sturm to end of lathe and see if that helps.

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On Tue, 16 Jul 2002 14:19:45 +1200, hughes b wrote:

> Try adding the keyword sturm to end of lathe and see if that helps.
 
Yes, it did thanks.  Any enlightenment following?

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On Tue, 16 Jul 2002 14:19:45 +1200, hughes b wrote:

> Try adding the keyword sturm to end of lathe and see if that helps.
 

The docs with 3.5 say this for Sturm

lathe (only with quadratic splines)

So now I have an Idea why it works, are the docs wrong here?

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"Rob Brown-Bayliss" <rob### [at] zoismorg> wrote in message
news:3d33a0e8@news.povray.org...
>
> The docs with 3.5 say this for Sturm
>
> lathe (only with quadratic splines)
>
> So now I have an Idea why it works, are the docs wrong here?

Oh? Hmmm. Well I only knew it wasn't applicable to the linear spline.

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Rob Brown-Bayliss <rob### [at] zoismorg> wrote:
> Yes, it did thanks.  Any enlightenment following?

  The 'sturm' keyword turns on the sturmian root solver algorithm, which is
slightly slower than the default algorithm, but gives a more accurate result.
With higher order polynomials the mathematically correct result can't be
calculated (I think that a polynomial of order 4 is the largest which has
a well-defined unique solution formula). For higher order polynomials some
approximation algorithm has to be used.
  That's about everything I know about 'sturm'.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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