Author: Laurence D. Finston

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Last updated: April 29, 2006

Top | |

Introduction | |

Classifying Points with Respect to a Cuboid | |

Intersections | |

Cuboid–Linear Path | |

Cuboid–Plane | |

Contact |

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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.

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**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

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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

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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)

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