David Wallace <dar### [at] earthlinknet> wrote:
> If I have a complex transform like:
>
> <code>
> #macro ReorientCenter(Point1,Axis1,Point2,Axis2)
>    #local vX1=vnormalize(Axis1);
>    #local vX2=vnormalize(Axis2);
>    #local vY=vnormalize(vcross(vX1,vX2));
>    #local vZ1=vnormalize(vcross(vX1,vY));
>    #local vZ2=vnormalize(vcross(vX2,vY));
>    translate -Point1
>    matrix < vX1.x, vY.x,vZ1.x, vX1.y,vY.y,vZ1.y, vX1.z,vY.z, vZ1.z, 0,0,0 >
>    matrix < vX2.x,vX2.y,vX2.z,  vY.x,vY.y, vY.z, vZ2.x,vZ2.y,vZ2.z, 0,0,0 >
>    translate Point2
> #end
> </code>
>
> How would I retrieve the resulting matrix so that I could use it in a file like
> this:
>
> #write (lFile, "object { Lamb matrix <",mxx, mxy, mxz, myx, myy, myz, mzx, mzy,
> mzz, mtx, mty ,mtz,"> }n")
>
> My guess would be this:
>
> <code>

.....

> </code>
>
> Does anyone have an easier solution?

Apart from some possible optimizations, an illegal keyword and questionable
use of a global variable and, your guess seems ok. (Which POV-Ray version
are you using btw. ?)

- But why do you want to do it that way instead of just writing out the
transformations to the file directly ?

Like this:


#macro AppendReorientCenter(FileName, Point1, Axis1, Point2, Axis2)

  #local vX1 = vnormalize(Axis1);
  #local vX2 = vnormalize(Axis2);
  #local vY = vnormalize(vcross(vX1, vX2));
  #local vZ1 = vcross(vX1, vY);
  #local vZ2 = vcross(vX2, vY);

  #fopen File FileName append
  #write(File, "ntransform {")
  #write(File, "n  translate ", -Point1)
  #write(File, "n  matrix <")
  #write(File, "n    ", vX1.x, ", ", vY.x, ", ", vZ1.x, ", ")
  #write(File, "n    ", vX1.y, ", ", vY.y, ", ", vZ1.y, ", ")
  #write(File, "n    ", vX1.z, ", ", vY.z, ", ", vZ1.z, ", ")
  #write(File, "n    ",     0, ", ",    0, ", ",     0)
  #write(File, "n  >")
  #write(File, "n  matrix <")
  #write(File, "n    ", vX2.x, ", ", vX2.y, ", ", vX2.z, ", ")
  #write(File, "n    ",  vY.x, ", ",  vY.y, ", ",  vY.z, ", ")
  #write(File, "n    ", vZ2.x, ", ", vZ2.y, ", ", vZ2.z, ", ")
  #write(File, "n    ",     0, ", ",     0, ", ",     0)
  #write(File, "n  >")
  #write(File, "n  translate ", Point2)
  #write(File, "n}")
  #fclose File

#end // macro AppendReorientCenter


#declare YourFileName = "ReorientCenterTrans.txt";
#fopen FileHandle YourFileName write
#fclose FileHandle

AppendReorientCenter(
  YourFileName,
  <1, 3, 4>, <1, 5, 7>, <6, 4, 2>, <1, 9, 1>
)

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