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Using this procedure as a
starting point, we can now draw
a slightly more complex shape
that contains five leaves. Our
new procedure, called Leaves,
and its output are shown in
Figure 4-28. As you can see, we
only had to call the Leaf pro- Figure 4-28: The Leaves procedure calls the
cedure in a repeat loop with Leaf procedure five times with 72° turn angle
an appropriate turn angle in between each call .
between.
We can now use Leaf and
Leaves to build up something
that is even more complex: a branch with leaves on it. Our Branch proce-
dure and its output are illustrated in Figure 4-29. The sprite moves forward
40 steps, draws a single leaf (by calling the Leaf procedure), moves an addi-
tional 50 steps forward, draws five leaves (by calling the Leaves procedure),
and finally returns to its starting position.

40 50

Initial (and final)
direction of sprite.

Figure 4-29: The Branch procedure and its output

Let’s take this up another
notch. How about using the
Branch procedure to create a
complex drawing of a flower?
Our new procedure, called
Flower, and its output are
shown in Figure 4-30. The
procedure simply calls the Figure 4-30: The Flower procedure and its
Branch procedure six times in output
a loop with 60° turn angle in
between.
We can keep going on and on, but the idea should now be clear. We
started with a simple procedure called Leaf and used it in a new proce-
dure (called Leaves) to create a complex pattern. The Branch procedure
relied on these two procedures to create something more complicated. The
Flower procedure then used Branch to draw an even more complex pat-
tern. If we wanted to, we could create a procedure that draws an entire tree
of flowers and yet another to draw a garden full of trees.

88 Chapter 4
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