Project Overview

Over the course of the next several lessons, you will be building a mod that will build an entire battle arena and spawn several waves of enemies.

To begin this project, we need to build a large hollow box area that will serve as the battle arena. Though you can always switch to creative mode and build this manually, there are 2 benefits to letting the code build the structure:

You can easily build it multiple times.
You will expand your coding knowledge!

To build a hollow box for the battle arena, we can use the fill with block and set the build settings to hollow.

Remember that this block will fill an area starting with the from position and ending at to. How do we know which coordinates to use for from and to?

To learn that, we need to visualize the box. Lets say the dimensions of our battle arena are roughly 30x30x30 blocks, and the player is at the middle of the box. Now we need to choose two opposite corners of the box to use for from and to. In this example, we will pick the bottom left corner and top right.

The player is located at position (0, 0, 0). To go from the player to from, notice that you have to go 15 blocks left (half the width of the box) and 15 blocks backwards (half the length), and one block down (the floor of the battle arena is below the player).

That gives us the coordinates (-15, -1, -15) for from.

To go from the player to position to, we go 15 blocks right, 15 forward, and 30 up, giving us the coordinates (15, 30, 15).

Note: technically, if we go 15 blocks to the left to reach from, 15 to the right to reach to, and the player starts at 0, that would make our box 31 blocks long. In reality, this box's dimensions are 31x31x31.

We didn't correct that at the beginning of the lesson in order to simplify the discussion.

We can use these numbers to complete our mod. Let's make a mod that will build a giant block of glass around the player whenever the player types arena in the chat. The code will look like this

And the final result should look like this.

Building the Arena - Part 1