Gamemaker Academy
Spring 2004

Week 1: Let's Make A Game
In week 1 we'll look at a few games and make our own "breakout" game. We'll also talk about all the things that go into a game and you'll be ready to design your own game! Your assignment will be to bring a game idea to the next class.

Week 2: What's In A Game?
In week 2 you'll present your game ideas to the group and we'll discuss what makes a good game. Then we'll spend some hands-on time examining all of the things the Gamemaker tool can do for you. You'll start writing your game this week! Your assignment will be to "detail" your game idea. If your game idea was "a frog hops across a road and tries to not get hit by a truck", your detail may include how many trucks go by and how fast and how wide the road is and how scoring will work and how many lives you get and what the next level will look like and...

Week 3: Putting It All Together
We'll review Gamemaker and all the things that make a game: objects, events, properties, sprites, rooms, and so on, and by the start of week 3 you'll know what all those things mean! We'll talk about what to do when things go wrong, but mostly you'll be building your game! Now that you've seen what the real world of Gamemaker is like, your assignment will be to revise the detail you came in with. You may decide that you want trucks to come from both directions, and there should be a manhole to fall down and having a pickup truck try to run down the frog is Just Too Hard!

Week 4: Peer Review
By this time you'll know what you can and can't do, and what's easy and what's just way too tricky. You'll each discuss your detail in, um, detail with the group. We'll exchange ideas and maybe I'll give up a secret or two to make your game writing a bit easier.

Week 5: A Good Start...
After a quick review of events and actions, you'll spend the rest of the class creating your game. Questions are answered, and answers are questioned.

Week 6: ...Making Progress...
You'll learn some of the cooler Gamemaker tricks and get back to building your game.

Week 7: ...And We're Done!
A few more tricks and it's back to building. How do you know when you're done? The class ends and I take your games away (until next week).

Week 8: Take a Bow
You each get a CD with your personally registered copy of Gamemaker and all of the games the class produced. We'll share the games and see what you've created.

Need help? Send an e-mail to me at games@c-ease.com

Glossary

action	How the game responds to an event.
alarm	An action that causes an alarm event to occur a specific number of steps in the future.
animation	A gif image may contain several individual images that are displayed in sequence to produce an animation. An Animation End event is fired at the end of the animation sequence.
background	the image(s) that underlay the objects in a room. They are static, i. e. they cannot collide with or block objects. Several backgrounds may be laid on top of each other, and a background can be declared as "foreground" to allow it to be displayed over objects (e. g., clouds obscuring aircraft objects).
event	a way of informing objects that something has happened.
expression	a mathematical formula that describes an aspect of an action. For instance, to make an object jump a bit to the right of the mouse position, you might set the x position to mouse_x + 4. An expression returns a value.
function	a (usually) complex expression hidden in a single operation. Functions are called by name and an argument, such as string_length("abcde") to return the length of the string "abcde". The most common function is random(arg) which returns a number from zero up to (but not including) "arg". Functions can be used in expressions. For example, random(6) + 1 would simulate a die roll (return a number from 1 to 6).
gif	A common image format. Gifs can be animated.
instance	an object, as it appears in the game. There may be multiple instances of a single object. In general, all exhibit the same behavior (that is, they look the same and respond with the same actions to the same events).
key press	An event that occurs when a key is pressed, but not repeated when the key is down (as a keyboard event is).
key release	An event that occurs when a key is released, but not repeated when the key is down. For instance, in a pinball game the plunger may jump to its start position at key press, move back during the keyboard event, and shoot forward when key release is detected.
midi	A very efficient format for storing music. Generally used for background music.
object	a template for instances. Objects define the events and actions of the instances, which actually appear in the game.
persistence	how long something lasts. For objects, it determines whether it will exists from room to room. For a room, it defines whether the room will look the same when a user returns to it.
property	A variable that is part of an instance. For example x refers to the current horizontal location of an instance.
resource	Anything in the game: backgrounds, objects, sprites, sounds, tiles, etc.
room	The screen upon which objects are placed.
script	A block of code that you can write as an action
sprite	What you see when you look at an instance in a room.
step	The basic unit of "time" which guides the game. Normally, a step is equal to 1/30 of a second, but that can be changed.
tile	Small bits of background that can be used to build up a complex room.
variable	A way to save information to use later. Generally used in scripts; most game writers will use object properties instead.
view	A way to display only a portion of a room at a time.
wav	An uncompressed sound generally used to provide short sound effects during a game ("boing" for a bounce, or a short tune when a character dies).

Events

Name	Fired	Typical Action
Create	when an instance is created	start moving
Destroy	just before the instance is destroyed	play a sound; create a new instance elsewhere
Alarm	when the alarm "time" becomes zero	create a new instance
Step Start	at the very start of the step	cancel an alarm before it's triggered
Step	in the middle, just before instances are moved	test a variable
Step End	near the end, before redrawing the room	snap to grid before displaying
Collision	when two instances touch	bounce
Keyboard	when a key is down	increase speed
Key Press	when a key is first pressed	start movement
Key Release	when a key is released	stop movement
Mouse down	when the specified button is pressed and the mouse is over that instance.	increase score
Mouse Press	when the specified button is first pressed and the mouse is over that instance.	play a sound
Mouse Release	when the specified button is released and the mouse is over that instance.	move the instance
Global Mouse Press	When any button is pressed and the mouse is anywhere over the game.	move toward the mouse pointer
Global Mouse Release	When any button is released and the mouse is anywhere over the game.
Joystick direction	When the joystick is pointing in any of the four primary directions (two events will occur if the joystick is at a diagonal)
Joystick button	When the specified button is down
Outside	when the instance is completely outside the room	destroy the instance
Boundary	when the instance touches the boundary	bounce
Game Start	when the game begins	start music
Game End	when the game ends	show hi-score table
Room Start	when the room is first displayed	start alarms
Room End	when the room is exited	pause and play music
No More Lives	when the lives property is set to zero	end game, show hi score table, play music
No More Health	when the health property is set to zero	reduce number of lives, reset health
End of Animation	when the current sprite animation ends	destroy instance
End Path	when the path the instance is following ends	restart path
User Defined	when an action is to fire a user-defined event
Draw	when the instance is being drawn	draw sprite image based on direction of movement

Actions

Action	Does
Start Moving In A Direction	choose one or more of eight directions and a speed to move at. Selecting more than one will cause a random choice.
Set Direction & Speed	choose a precise direction (degrees) and speed
Set Horizontal Speed	set the horizontal speed
Set Vertical Speed	set the vertical speed
Move Toward a Point	specify a point (x and y) and speed and move toward it at that speed. For instance, to move toward the mouse, set x to mouse_x and y to mouse_y
Set a Path	select a path resource for this object
Set Gravity	set a force that "pulls" the object toward a gravity point. Usually, the angle is 270 ("down")
Set Friction	set a force that slows down the object
Jump to a given position	specify a point (x and y) to move the object to.
Jump to the start position	move the instance to its "create" position
Jump to a random position	move the instance to some non-collision position in the room
Snap to a grid	Ensure the object is on a grid position
Reverse Horizontal	Reverse horizontal direction and speed
Reverse vertical	Reverse vertical direction and speed
Move to contact position	Move in the direction specified until a collision would occur
Bounce	Change direction as if the instance "bounced" off the instance it collided with
Create	Create a specified object instance at a specified location
Change	Change the specified object into another object type
Destroy	Destroy the specified object.
Destroy at	Destroy any objects at a specified (x and y) position.
Change sprite	Use a different sprite to display for this object
Play sound	start a specified sound resource
Stop sound	stop a specified sound resource
if sound is playing	test to see if the sound resource is playing
Goto previous room	End this room and start the previous room
Goto next room	End this room and start the next room
Restart room	Restart this room.
Goto different room	End this room and go to a specified room
If previous room exists	Test to see if the previous room exists
If next room exists	Test to see if the next room exists. It is important to use this before going to the next room, unless you are certain there are more rooms.
Set alarm	Set a specified alarm to trigger after a specified number of steps. If you want your alarm to be regular, you must put this in the alarm event
Sleep	Freeze the game for a specified time
Set timeline	Specify a timeline for this instance to follow
Set timeline position	Specify a position on the timeline
Display a message	Display a message box for the player
Show game information	Show the "about" information you create
Restart game	End the current game and start over
End game	End the current game
Save game	Save the current game state
Load game	Load the game state
If a collision	Execute the next statement if there is a collision at a specified location
If no collision	Execute the next statement if there is no collision at a specified location
If object is at a position	Execute the next statement if there is an instance of a specific object at a location
If number of instances is	Execute the next statement if the number of instances of an object equal to, smaller than, or larger than a specified value
If dice is 1	Execute the next statement if a random number in the range you specify is "1". For instance, specify 2 to get a coin toss, or 6 for a die.
If the user answers yes	Display a message and execute the next statement if the user answers yes
If an expression is true	Execute the next statement if the specified expression returns true
If a mouse button is pressed	Execute the next statement if the specified mouse button is pressed. The mouse can be anywhere within the game.
If aligned with a grid	Execute the next statement if the instance is aligned with the grid.
Else	Execute the next statement if the previous "if" section was not executed. For instance, [if the dice returns 1] move to start [else] destroy self would move to start if the random number was 1, otherwise the object would self-destruct.
Start block	Use to execute more than one statement after an "if" or "else". Each start block must have an end block
End block	End the block of statements.
Repeat next action	Perform the next action (or block) a specified number of times
Exit event	Stop executing actions for this event
Draw sprite	Draw a specified sprite
Draw background	Draw a background resource at a specified location. You can specify if it is to be tiled.
Draw rectangle	Draw a rectangle. Specify the size and location.
Draw ellipse	Draw an ellipse (or circle). Give the size and location.
Draw a line	Draw a line. Give the start and end.
Draw text	Draw text at a given location.
Set color	Change the color of whatever is drawn next.
Set font	Change the font for the subsequent text.
Fullscreen mode	Change to full screen (arcade) mode. The windows taskbar and borders will disappear.
Set score	Change the score
If score is	Execute the next statement if the score has a specified value
Draw score	Display the score in the room.
Clear highscore	Clear the high score table
Show highscore	Display the high score table
Set # lives	Change the number of lives
If # lives is	Execute the next statement if the number of lives has a specified value
Draw # lives	Display the number of lives in the room.
Draw # lives as image	Display a number of icons representing the number of lives.
Set health	Change the health value
If health is	Execute the next statement if health has a certain value
Draw health bar	Display the health bar in the room
Set caption information	Display lives/score/health in the title bar
Run script	Execute a script (short code segment)
Run code	Execute a longer code segment
Set variable	Change a property for an object or instance.
If variable	Execute the next statement if the property has a specified value
Draw variable	Display the value of the variable in the room
Call inherited event	If the object has a parent, execute the parent's event actions
Comment	Information to yourself

Common Properties

Property	Meaning	Example
x	Horizontal position of instance. Left is 0	These all work together. If you create an instance at x=(room_width / 2) and y=(room_height / 2) it will appear in the middle of the room. Setting its vspeed=-2 and hspeed=2 means it will travel up and to the right. This is the same as setting the direction=45 (degree angle) and speed=2.83 (trust me).
y	vertical position of instance. Top is 0
hspeed	horizontal speed of instance. Right is positive
vspeed	vertical speed of instance. Down is positive
direction	direction instance is moving (0=right, 90=up, etc)
speed	vector speed instance is moving at
visible	visible status of the instance	To magically transport your instance, set visible=false (or 0) and change its position. Set an alarm for, say, 5 steps and when the alarm fires make it visible. It will reappear at its new location at that time. Keep in mind that collisions can occur even when invisible.
image_single	show a single image from an animated sprite	Make a sprite that has images of your character facing left, right, up, and down. Use image_single to choose the appropriate one, based on direction.
score	current value of score	Let's apply these together. Use a series of "if expression"s: if score mod 10 = 0 then health=health + 10. if health > 100 then lives = lives + 1. If lives > 5 then destroy all monsters. What that will do is eventually reward the player's skill. Here's the English: Every 10 points (mod 10 means "get the remainder when divided by 10"), add 10 health points. When health gets above 100, give the player an extra life. When the player gets six or more lives, destroy all of the monsters. These statements aren't perfect. For instance, you'll get an extra health when the score is 0, so it should only be placed after a statement that raises the score. Also, since the health stays above 100, every time this is executed you'll get an extra life. There needs to be a way to prevent that.
lives	current value of lives
health	current value of health
mouse_x	horizontal position of the mouse	This can be used to create your own mouse pointer! In the draw event of any object, draw a sprite that represents the mouse at mouse_x and mouse_y
mouse_y	vertical position of the mouse
xprevious	The x position at the previous step	If an instance moves to a "back" button, set the x and y to xprevious and yprevious. This would work whether the object stepped onto the button or "jumped" there.
yprevious	The y position at the previous step
xstart	The x position at the start of this room	When a life is lost, set the instance's x and y to xstart and ystart to begin again without restarting the entire room. Pac-man uses this so the objects that were eaten remain eaten.
ystart	The y position at the start of this room
show_cursor	set to true to display the cursor; false to hide it	If the mouse is unused, set variable show_cursor to false
background_color	change the background color	using "set variable" to set backgdound_color to make_color(score, health, lives) will cause the background color to change as each of those three properties changes. At the start of the game, the background will be quite green. As health and lives go down and the score rises, the color will change to red.
room_width	the width of the room	To place an object in the center of the room set x = room_width / 2 and y = room_height / 2
room_height	the height of the room

Common Functions

Name	Function	Example
random(arg)	return a random number from 0 up to (less than) arg	to move in a random direction, specify random(360). To move at a speed between 2 and 5, set speed to random(3) + 2 (the result will be anywhere from 2 up to 4.999999999)
round(arg)	return arg, rounded to an integer	All of these return an integer value when you need it. You may want to get adjust the player's score based on his remaining energy level at the end of a room. If the energy can be a real number from 0.000 to 9.999 you can be honest and use round(energy), you can be stingy and use floor(energy) or you can be generous and use ceil(energy).
floor(arg)	return arg, rounded down to an integer
ceil(arg)	return arg, rounded up to an integer
min(arg1, arg2)	return the smaller of arg1 and arg2	To double the current score, but not add more than 10 points use score = score + min(score, 10). To double the current score, but add at least 10 points use score = score + max(score, 10).
max(arg1, arg2)	return the larger of arg1 and arg2
point_distance(x1, y1, x2, y2)	return the distance from point x1, y1 to point x2, y2	An exploding bomb may want to destroy an object if it is within 50 units of the bomb. You could test this with an "if expression" point_distance(x, y, enemy.x, enemy.y) < 50. Or you may want to move to the top left corner of the screen with direction = point_direction(x, y, 0, 0).
point_direction(x1, y1, x2, y2)	return the direction from point x1, y1 to point x2, y2
real(str)	change a string to a real number	When creating your own variables, you often will want to "stick them together" or add them, depending on their use. If you have two strings string1 = "10" and string2 = "5" and you display string1 + string2 you will see "105". If you have two numbers num1 = 10 and num2 = 5 and you display num1 + num2 you will see 15. You can change numbers to strings and back again with these functions.
string(val)	change a real number to a string
string_length(str)	get the length of the string	If the player entered his name and there is only room to display five characters you can use an "if expression" to shorten it: if string_length(name) > 5 then string = string_copy(name, 0, 5).
string_copy(str, index, count)	get a partial string. Returns count characters of str starting from index
instance_nearest(x, y, obj)	tells you which instance of type obj is closest to position x, y.	The zapper at x, y destroys the closest object to it: inst = instance_nearest(x, y, all); inst.instance_destroy(). There are three new things here: the first function returns the identity of that particular instance that's closest. Statements are separated by semi-colons. putting an instance or object type name followed by a dot followed by a function or property means "apply the function to that instance" or "use the property of that instance". So if I'm a paddle and I set x = x + 10, I move 10 pixels to the right. If I set x = ball.x + 10 I move 10 pixels to the right of the ball.
set_cursor(cur)	display the cursor as a specific windows cursor. cur can be cr_default, cr_none, cr_arrrow, cr_cross, cr_beam, cr_size_nesw, cr_size_ns, cr_size_nwse, cr_size_we, cr_uparrow, cr_hourglass, cr_drag, cr_nodrop, cr_hsplit, cr_vsplit, cr_multidrag, cr_sqlwait, cr_no, cr_appstart, cr_help, cr_handpoint, cr_size_all	Use script to call set_cursor(cr_hourglass) and the mouse pointer will turn into the hourglass shape.

Contact: games@c-ease.com