# NAME

Math::Geometry - Geometry related functions

# SYNOPSIS

```
use Math::Geometry;
@P2=rotx(@P1,$angle);
@P3=rotx(@P1,$angle);
@N =triangle_normal(@P1,@P2,@P3);
@ZP=zplane_project(@P1,$d);
```

# NOTES

This is about to get a massive overhaul, but first im adding tests, lots of lovely lovely tests.

Currently for zplane_project onto a plane with normal of the z axis and z=0, the function returns the orthographic projections as opposed to a perspective projection. I'm currently looking into how to properly handle z=0 and will update it shortly.

# DESCRIPTION

This package implements classic geometry methods. It should be considered alpha software and any feedback at all is greatly appreciated. The following methods are available:

## vector_product.

Also known as the cross product, given two vectors in Geometry space, the vector_product of the two vectors, is a vector which is perpendicular to the plane of AB with length equal to the length of A multiplied by the length of B, multiplied by the sin of @, where @ is the angle between the two vectors.

## triangle_normal

Given a triangle ABC that defines a plane P. This function will return a vector N, which is a normal to the plane P.

```
($Nx,$Ny,$Nz) =
triangle_normal(($Ax,$Ay,$Az),($Bx,$By,$Bz),($Cx,$Cy,$Cz));
```

## zplane_project

Project a point in Geometry space onto a plane with the z-axis as the normal, at a distance d from z=0.

` ($x2,$y2,$z2) = zplane_project ($x1,$y1,$z1,$d);`

## rotx

Rotate about the x axis r radians.

` ($x2,$y2,$z2) = rotx ($x1,$y1,$z1,$r);`

## roty

Rotate about the y axis r radians.

` ($x2,$y2,$z2) = roty ($x1,$y1,$z1,$r);`

## rotz

Rotate about the z axis r radians.

` ($x2,$y2,$z2) = rotz ($x1,$y1,$z1,$r);`

## deg2rad

Convert degree's to radians.

## rad2deg

Convert radians to degree's.

## pi

Returns an approximate value of Pi, the code has been cribed from Pg146, Programming Perl 2nd Ed.

# EXAMPLE

` use Math::Geometry;`

# AUTHOR

```
Greg McCarroll <greg@mccarroll.org.uk>
- http://www.mccarroll.org.uk/~gem/
```

# COPYRIGHT

Copyright 2006 by Greg McCarroll <greg@mccarroll.org.uk>

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html