Hi Monks,

lately I stumbled over my old c++ code
for fast rigid body rotations using
a rotational matrix formalism /1,2/.
Because I needed a snippet to be ready
fast, I rewrote the stuff in plain Perl
without doing a deep investigation into
CPAN first.

After having completed the task, I
started to lookaround there but couldn't
find anything appropriate which does
somehow what I needed.

Simple example - say we have a 3D rigid body
template consisting of 5 coordinates (+ labels):

 my @tmpl = ( [0,0,0, 'A'],
              [1,0,0, 'B'],
              [2,0,0, 'B'],
              [3,0,0, 'B'],
              [4,0,0, 'B'],
              [5,0,0, 'A'] );
[download]

Say we need to construct an ensemble
of copies of rigid bodies by applying random
translations and rotations around ar-
bitary axes on the template,
like (pseudocode):

 ...
 my $axis = [ 0, 0, 1 ]; # may be arbitary axis, always normalized
 my @ensemble;
 
 for my $id (0 .. 999) {
    my $angle = deg2rad(rand(360)); # rotate around arbitary  
                                    # axis by .. degrees
    # make rotation matrix
    my $m = setrotmatrix($angle, $axis); 

    # make new rigid body instance from template
    my $p = deepcopy_body( \@tmpl );
    
    # apply rotation (matrix x vector) to rigid body
    rotate_body( $p, $m );

    # apply some translation by a displacemnent vector
    translate_body( $p, [$dx, $dy, $dz)] );

    # store the new body coordinates
    push @ensemble, $p;
 }
 ...
[download]

The above code should make my intention clear
before I start to work out a module + XS
matrix operations, which modules should I
have considered before?

Regards & thanks

mwa



/1/ - Ha,C. and Radcliffe,C.W. (1978) Kinematics
       and Mechanism Design. Wiley, New York, 45.
/2/ - http://peds.oxfordjournals.org/cgi/reprint/16/10/717