Building BoundingBox

1

Hello everyone! I’m having troubles creating BoundingBox: i’m creating a Monogame project on Visual Studio 2015 and i have to design some BoundingBox knowing all the vertexes. I’m trying to use CreateFromPoint method giving all the 8 points, but it creates a cube with the max and min values for all 3 coordinate, while i have to create parallelepiped with vertexes i give. How can i reach my goal? Thank you all!

2

A boundingbox in MG is an axis aligned 3D box so you can’t have it represent arbitrary geometry like that.

3

I don’t want to create an arbitrary shape box, but a box with a rectangular base instead of a square ones. Is it possible?

4

Do you want AABB or OOBB ?

5

Yes, the BoundingBox class represents a 3D box (a cuboid) so that’s possible.

You can’t create a parallelepiped though. A BoundingBox is defined only by a min and max point.

The CreateFromPoints method returns the box that encapsulates the give points. So

is the expected behavior here.

6

I want an OBB of a non-mobile object.

7

So how can i do to create a rectangular based box not aligned with XYZ axis?

8

Write your own class. Like I said the BoundingBox class in MonoGame is axis-aligned and it’s defined by a min and max point. You’ll need some more data to represent an oriented box. There’s many ways you can represent a box like that and what’s best depends on what you plan on using it for. For example you can have a position, normals and length along the boxes axes. Or you can use a matrix that transforms a unit cube into your box. I’ve never written collision detection/intersection code (I guess that’s what you’re looking to do) so I’m not sure what’s easiest.

1 Like
9

As @jjagg suggested, you should write your own class (as I did), inheriting from the current boundingbox class if you need/think it is easier to start with.
There are plenty of tutorials and sources available on the internet to get inspiration for your own implementation :wink:
Doing so you will need to write/adapt your own intersection code to get it work with monogame bounding volumes or write your own boundingfrustrum, sphere…