Author: Laurence D. Finston.

This copyright notice applies to the text and source code of this web site, and the graphics that appear on it. The software described in this text has its own copyright notice and license, which can be found in the distribution itself.

Copyright (C) 2005, 2006, 2007 The Free Software Foundation

Permission is granted to copy, distribute, and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of this license is included in the file COPYING.TXT

Last updated: April 29, 2006

Top | |

Introduction | |

Classifying Points with Respect to a Cuboid | |

Intersections | |

Cuboid–Linear Path | |

Cuboid–Plane | |

Contact |

Back to top

Back to Polyhedra page

Back to main contents

Back to main page

The type **cuboid** in the 3DLDF language
corresponds to **class Cuboid** in the C++ code.
**class Cuboid** is defined in the file
cuboid.web.
**class Cuboid** already existed in
Release 1.1.5.1, so it's documented in
the
manual. This web page contains examples and illustrations of newer features.

Back to contents

Back to top

Back to Polyhedra page

Back to main contents

Back to main page

**points** can be classified according
to their position with respect to a
**cuboid**
by using the **location** operator:

cuboid c; c := unit_cuboid scaled (20, 16, 10) rotated (-20, 15); draw c; point p[]; p0 := (0, 1, 1); message "p0 location c:"; show p0 location c; rectangle r[]; r0 := get_rectangle 0 c; p1 := mediate(get_point 0 r0, get_point 3 r0, 1/3); message "p1 location c:"; show p1 location c; r1 := get_rectangle 4 c; p2 := mediate(get_point 0 r1, get_point 2 r1) shifted (0, 2); message "p2 location c:"; show p2 location c; end;

**location** returns one of the following numerical values:

0: | The point
lies on the surface of the cuboid.
| |

1: | The point
lies within the cuboid.
| |

-1: | The point
lies outside the cuboid.
| |

INVALID_NUMERIC:
| An error occurred. |

In the following image, **p _{0}** lies inside the

Back to contents

Back to top

Back to Polyhedra page

Back to main contents

Back to main page

2005.12.16.

The following four images illustrate the intersections of a
**cuboid** and a linear **path**.
The 3DLDF code for generating these images is in
cubd_02.ldf.

Perspective Projection

Parallel Projection, X-Z Plane

Parallel Projection, X-Y Plane

Parallel Projection, Z-Y Plane

Back to contents

Back to top

Back to Polyhedra page

Back to main contents

Back to main page

2005.12.16.

The following four images illustrate the intersection of a
**cuboid** and a **plane**, which, in general,
is a **polygon**. It could also be a **point**, but I haven't accounted
for this case yet. The 3DLDF code for generating these images is in
cubd_06.ldf.

Parallel Projection, X-Z Plane (scaled 3/4 size)

Parallel Projection, X-Y Plane (scaled 3/4 size)

Parallel Projection, Z-Y Plane (scaled 3/4 size)

Back to contents

Back to top

Back to Polyhedra page

Back to main contents

Back to main page