What are BoxF?

[YueParticipant]

I’m trying to understand why when creating a simple cube, I have to use BoxF which receives two parameters, could someone help me with a simple explanation?

[nerobotParticipant]

BoxF is an alias for Box<Float>, Box type allow us to set cubic bounds.

It has many constructors, see the sources:

https://github.com/blitz-research/monkey2/blob/develop/modules/std/geom/box.monkey2

[YueParticipant]

I greatly appreciate your response, I just want to understand that, although the examples use it, I can not understand its parameters when creating a cube. A simple explanatory example?, with the objective of understanding the matter better since the documentation does not say much.

Thank you.

[DruggedBunnyParticipant]

I’ve only used the form defining opposite corners of a cube/box:

Monkey

New Boxf (x0, y0, z0, x1, y1, z1)

1	New Boxf (x0, y0, z0, x1, y1, z1)

In real-world use, this might look like:

Monkey

Local cube:Model = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.White))

1 2	Local cube:Model = Model.CreateBox (New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5), 1, 1, 1, New PbrMaterial (Color.White))

… where x0, y0, z0 define one extreme corner — in this case being left 0.5, down 0.5, towards camera 0.5 — and x1, y1, z1 define the opposite corner; in this case right 0.5 (forming total width of 1.0), up 0.5 and forward 0.5.

For further clarity, you might store the box as a Boxf and pass it to CreateBox:

Monkey

Local cube_box:Boxf = New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5) Local cube:Model = Model.CreateBox (cube_box, 1, 1, 1, New PbrMaterial (Color.White))

1 2 3

Local cube_box:Boxf = New Boxf (-0.5, -0.5, -0.5, 0.5, 0.5, 0.5)   Local cube:Model = Model.CreateBox (cube_box, 1, 1, 1, New PbrMaterial (Color.White))

As far as I can tell, you only really need 1, 1, 1 for the x, y, z segments — you might pass in more if you want to manipulate the cube’s vertices into another shape.

So the box is:

• -0.5 to 0.5 horizontally – New Boxf (x0, -0.5, -0.5, x1, 0.5, 0.5);
• -0.5 to 0.5 vertically – New Boxf (-0.5, y0, -0.5, 0.5, y1, 0.5);
• -0.5 to 0.5 depth-wise – New Boxf (-0.5, -0.5, z0, 0.5, 0.5, z1).

… meaning it measures 1.0 in all directions.

Another way to define it, if you want to specify a particular size:

Monkey

Local size:Float = 10.0 Local box:Boxf = New Boxf (-size * 0.5, -size * 0.5, -size * 0.5, size * 0.5, size * 0.5, size * 0.5)

1 2	Local size:Float = 10.0 Local box:Boxf = New Boxf (-size * 0.5, -size * 0.5, -size * 0.5, size * 0.5, size * 0.5, size * 0.5)

Or…

Monkey

Local box:Boxf = New Boxf (-width * 0.5, -height * 0.5, -depth * 0.5, width * 0.5, height * 0.5, depth * 0.5)

1 2	Local box:Boxf = New Boxf (-width * 0.5, -height * 0.5, -depth * 0.5, width * 0.5, height * 0.5, depth * 0.5)

The parameters define opposite corners of the cube:

Monkey

New Boxf (-, -, -, +, +, +)

1	New Boxf (-, -, -, +, +, +)

… and if you find you still struggle, just wrap Model.CreateBox into a CreateCube function (like Blitz3D!), passing in the width, height, depth and a PbrMaterial (plus potentially the optional parent entity), and returning the Model.

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