Question

In Chapter 7 we used arrays of strings to describe a two-dimensional grid. We can do the same here. It will allow us to design levels without first building a level editor.

A simple level would look like this:

var simpleLevelPlan = [
  "                      ",
  "                      ",
  "  x              = x  ",
  "  x         o o    x  ",
  "  x @      xxxxx   x  ",
  "  xxxxx            x  ",
  "      x!!!!!!!!!!!!x  ",
  "      xxxxxxxxxxxxxx  ",
  "                      "
];

Both the fixed grid and the moving elements are included in the plan. The x characters stand for walls, the space characters for empty space, and the exclamation marks represent fixed, nonmoving lava tiles.

The @ defines the place where the player starts. Every o is a coin, and the equal sign ( = ) stands for a block of lava that moves back and forth horizontally. Note that the grid for these positions will be set to contain empty space, and another data structure is used to track the position of such moving elements.

We’ll support two other kinds of moving lava: the pipe character ( | ) for vertically moving blobs, and v for dripping lava—vertically moving lava that doesn’t bounce back and forth but only moves down, jumping back to its start position when it hits the floor.

A whole game consists of multiple levels that the player must complete. A level is completed when all coins have been collected. If the player touches lava, the current level is restored to its starting position, and the player may try again.

This is a book about getting computers to do what you want them to do. Computers are about as common as screwdrivers today, but they contain a lot more hidden complexity and thus are harder to operate and understand. To many, they remain alien, slightly threatening things.