PacMan (Continued)
ACO PacMan Curriculum v2.0
Page 8 of 32
Scalable Game Design
Time to Create Behaviors for your Agents
Step 13
Create an agent
behavior
Click on an agent
and its behavior
window will
appear below the
world.
You are going to
drop and drag
the conditions (on
the left) and the
actions (on the
right) to create
the rules.
This rule says:
IF the user presses the up arrow,
AND I Do NOT See a Wall in the up direction,
THEN my PacMan will move UP
Tip: Click on the See condition, then the NOT button at the bottom of
the window to make the NOT see condition.
Create 3 more rules to make PacMan move right, left and down.
NOTE: Click on the rule you made, then click on the +RULE button
at the bottom of the window to create each new rule.
Step 14
Program the
PacMan to eat
the pellets.
First, take a moment to think about the PacMan and the Pellets
When the PacMan collides with the Pellets, then the Pellet
disappears, making it look like the PacMan ate it.
Take a look at this code when the Pellet sees the PacMan above or
below him: It says…
IF
I see a PacMan above or below me
THEN
…
erase myself (the pellet)
PacMan (Continued)
ACO PacMan Curriculum v2.0
Page 9 of 32
Scalable Game Design
Play with adding a wait time before erase. What happens when wait
before adding the pellet? Choose a wait time (or no wait time) that
you think makes the eating behavior look the way you want it.
Step 15
Program the
Ghosts to move
randomly
Click on the agent to add behaviors to that agent.
How can you make the Ghost move faster or slower? Experiment with
the number in the once every condition.
The ghost should also move on the pellets so add a second rule!
Be mindful of what will happen if both commands have the same time for
“once every”.
(see Appendix I:
Guidance on Ghost’s Random Movement
for more
help)
Step 16
Create rule to
end the game
when the
PacMan is next to
the Ghost
Click on PacMan
and add this rule.
Note: You need a
similar rule for
each different
Ghost shape.
This second Ghost rule says:
IF I am NEXT TO at least 1 PacMan
THEN, stop the simulation, show a message “You lose!” AND Reload
the World
Very Important Tip: Put
and/or
in your
Game ending rule.
If you forget to do this, AgentCubes Online will do the game ending rule
over and over until you are able to type the Return Key to click the OK on
the dialog box and then immediately after use the mouse to click on the stop
game button
(the red square).
If you cannot click on the stop game button before the dialog box appears,
you
must close the browser window, then open a new browser window, go to
AgentCubes Online, find your project and click on the edit button so it opens.
PacMan
ACO PacMan Curriculum v2.0
Page 10 of 32
Scalable Game Design
Student Handout 2
Part 2 – Making the Ghost Chase the PacMan
Step 1: The best
way to initialize PacMan’s S agent attribute is to set it when PacMan is drawn
on the world because then PacMan s attribute will always start at the same value.
To do this, create a new Method by clicking on the +Method button. Click on the word “on” in
the new method’s black and yellow striped tape and change the label from “on” to “when-
creating-new-agent”.
Your when-creating-new-agent method should look as follows:
If you use this method to set PacMan’s S attribute, make sure that you erase and redraw PacMan
and then SAVE the World.
So far, your Ghost just moves randomly, either just on the floor, or on the floor and the pellets…he
doesn’t actually chase the PacMan, does he? That’s about to change!
The Ghost will intelligently seek the PacMan agent using a computational thinking pattern called
“searching.” In this instance, we will use a specific method of searching called Hill Climbing.
Imagine the PacMan agent emits a scent. Hill climbing is a procedure or algorithm to find the
direction in which the scent is strongest.
The scent will spread out, or be propagated, by the ground agents using a computational thinking
pattern called “diffusion.” Diffusion is a fundamental process (physical, biological, and social) by
which objects move from areas of highest concentration to areas of lowest concentrations. The
closer to the source of the scent, the greater its value
1
.
This phase of the project introduces the concept of an “agent attribute,” which is unique
information that is stored within each occurrence of an agent. Computer scientists call this agent
attribute a local variable.
