Severi Salminen wrote:
> Severi Salminen wrote:
> 
>> Let's have a vector V which is random vector inside a hemisphere which
>> has a pole at 0,1,0 (just like the northern hemisphere of Earth). I want
>> to orient the vector inside a hemishere which has a pole pointing at
>> vector N. How do I do this? 
> 
> Example:
> 
> V = (0.71, 0.71, 0) //The random vector in "northern hemishpere")
> N = (-1,0,0) //The pole I want to orientate the random vectors to)
> 
> The result is
> 
> Vnew = (-0.71, 0.71, 0)


Some relevant macros in transforms.inc:

vtransform(vec, trans)
Reorient_Trans(Axis1, Axis2)
Point_At_Trans(YAxis)

I don't have time to test this, but I think this will work:

   #include "transforms.inc"
   #declare P = <0, 1, 1>;
   #declare N = <-1, 0, 0>;
   #declare V = <0.71, 0.71, 0>;
   #declare Vnew = vtransform(V, Reorient_Trans(P, N));

This should also work:

   #include "transforms.inc"
   #declare N = <-1, 0, 0>;
   #declare V = <0.71, 0.71, 0>;
   #declare Vnew = vtransform(V, Point_At_Trans(N));

-- 
Tor Olav
http://subcube.com

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