fix rotate 3D object Perl code - perl

Question

I wrote this code using C++ example from net to rotate my set of points in 3D.
##matrix is points and their 3D coordinates.
#rotated_matrix = rotate_l(\#matrix, 0);
sub rotate_l {
my $ref = $_[0];
my $x = 0;
my $step = 1;
#if rotx
if ($_[1] == 0) {
while ($$ref[$x][0]) {
$$ref[$x][1] += ($$ref[$x][1]*cos($step) - $$ref[$x][2]*sin($step));
$$ref[$x][2] += ($$ref[$x][1]*sin($step) + $$ref[$x][2]*cos($step));
$x++;
}
}
#if roty
if ($_[1] == 1) {
while ($$ref[$x][0]) {
$$ref[$x][0] += ( $$ref[$x][0]*cos($step) + $$ref[$x][2]*sin($step));
$$ref[$x][2] += (-$$ref[$x][0]*sin($step) + $$ref[$x][2]*cos($step));
$x++;
}
}
#if rotz
if ($_[1] == 2) {
while ($$ref[$x][0]) {
$$ref[$x][0] += ($$ref[$x][0]*cos($step) - $$ref[$x][1]*sin($step));
$$ref[$x][1] += ($$ref[$x][0]*sin($step) + $$ref[$x][1]*cos($step));
$x++;
}
}
return #$ref;
}
But something is wrong. Object size/form fails to stay same. And my math is not that good to realize why. I even not sure I need += or =?

Answer 1

Thx amon. As suggested this works:
##matrix is points and their 3D coordinates.
#rotated_matrix = rotate_l(\#matrix, 0);
sub rotate_l {
my $ref = $_[0];
my $x = 0;
my $step = pi;
#if rotx
if ($_[1] == 0) {
while ($$ref[$x][0]) {
$$ref[$x][1] = ($$ref[$x][1]*cos($step) - $$ref[$x][2]*sin($step));
$$ref[$x][2] = ($$ref[$x][1]*sin($step) + $$ref[$x][2]*cos($step));
$x++;
}
}
#if roty
if ($_[1] == 1) {
while ($$ref[$x][0]) {
$$ref[$x][0] = ( $$ref[$x][0]*cos($step) + $$ref[$x][2]*sin($step));
$$ref[$x][2] = (-$$ref[$x][0]*sin($step) + $$ref[$x][2]*cos($step));
$x++;
}
}
#if rotz
if ($_[1] == 2) {
while ($$ref[$x][0]) {
$$ref[$x][0] = ($$ref[$x][0]*cos($step) - $$ref[$x][1]*sin($step));
$$ref[$x][1] = ($$ref[$x][0]*sin($step) + $$ref[$x][1]*cos($step));
$x++;
}
}
return #$ref;
}
If I need to rotate not around (0,0,0), but against other point the best way is to translate to 0 point rotate and then translate back?

Answer 2

Just as an example of what I meant by what I recommend you do:
#! /usr/bin/env perl
use common::sense;
use YAML 'Dump';
sub translate {
my ($deltaX, $deltaY) = #{pop()}; # <-- don't mind this.
for (#_) { # <--- this is the important part
$_->[0] += $deltaX;
$_->[1] += $deltaY;
}
#_
}
my #points = ([0, 1], [0, -1], [-1, 0], [1, 0]);
print Dump([translate #points, [2, 2]]);
my $box = \#points;
print Dump([translate #$box, [5, 0]]);