Learn to Program with Small Basic

Then you set the graphics window’s size (lines 5–7), font size (line 8),
and position (line 9). Next, you position the text window to appear to the
right of the graphics window (lines 11–12). After drawing the background
image (lines 14–15), you create and position the text shapes that you’ll use
to show all the numbers on the game’s UI (lines 19–26). Then you load
and position the images for the knight, dragon, and arrow (lines 29–35).
Finally, you hide the images for the firing dragon and the arrow because
they aren’t needed at this time (lines 37–38): you’ll show these images when
Draggy breathes fire and Good Knight shoots the arrow.
When we built this program, we figured out where to place the text and
images (with the numbers we’re using) on the background’s image by using
a trial-and-error method (we guessed and tweaked it until we got it right).
You’ll likely need to do that when designing your own UIs for your awesome
future games.
Step 3: Add a Bit of Chance
Next, you need to add some luck to the game. Each time we run the game,
we want Good Knight to get a different number of arrows, be a random
distance away from the dragon, and have a different shield strength. To do
this, add the NewGame() subroutine in Listing 10-9 to your program.
1 Sub NewGame
2 dist = 9 + Math.GetRandomNumber(10) ' 10 to 19
3 arrows = Math.Floor(0.4 * dist) ' 4 to 8
4 shield = Math.Floor(0.4 * dist) ' 4 to 8
5 moveStep = 280 / dist ' Knight's move in pixels
6 EndSub
Listing 10-9: Setting up a new game
In line 2, you add 9 to a random number between 1 and 10, which sets
the distance, dist, between 10 and 19. This is the number of steps Good
Knight has to take to get to Draggy. Next, you set the number of arrows
as 40 percent of the distance (line 3). The farther the knight is from the
dragon, the more arrows he’ll have. In line 4, you set the strength of the
knight’s shield—again, as a fraction of his distance.
Let’s think about the moveStep line a little. The width of the background
image is 480 pixels. The width of the dragon is 100 pixels, and the width of
the knight is 100 pixels. When we place the dragon and the knight on the
background, the distance from the dragon’s right edge to the knight’s left
edge is 280 pixels. So every time Good Knight moves forward, we’ll move
his image to the left by 280 / dist pixels.
TIP
You can change the fraction in lines 3 and 4 from 0.4 to a different value to make
the game easier or harder. After you complete the game, try changing the fraction and
play the game a couple of times!
Solving Problems with Subroutines 141