I have read and expperimented and read and experimented before, buit I just
can't get thie one. I am using trace to locate an object on the surface of
another. no problem there. However, I can't figure out how to reorient the
object on the surface so that it aligns with the surface normal at the
point of intersection.

Could somebody shopw me a snippet of code that will do this? Somethin simple
like positioning a box on the surface of a sphere will do. I can take it
from there.

Thanks,

Tim

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If Norm is your normal vector, you have to rotate your traced object like
this in order to orient it:

rotate <degrees (atan2 (Norm.z,Norm.y)), 0, -degrees (atan2
(Norm.x,Norm.y))>


Norbert Kern

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Norbert Werner Kern wrote:
> If Norm is your normal vector, you have to rotate your traced object like
> this in order to orient it:
> 
> rotate <degrees (atan2 (Norm.z,Norm.y)), 0, -degrees (atan2
> (Norm.x,Norm.y))>
> 
> 
> Norbert Kern
> 
> 
Personally, I'd let POV do the work.

#include "Transforms.inc"
#include "maths.inc"

#declare N = <0,0,0> // Initial Normal Vector
#declare S = some_location // The initial position of the object to drop

trace(ENV, S, -y, N)

#if(vlength(N)!= 0)
object {
      YourObject
	texture { whatever }
	     Reorient_Trans(y,N)
	     translate S
      }
#end

Here's a good tutorial http://povray.tirnalong.com/ow.asp?DropOnSurface

And I'd be glad to post my macro, simple though it is, upon request.

Regards,

A.D.B

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