Game Design

Game Maker Terminology

Object

Item in a game that has behavior, such as a main character who can move

Sprite

A picture or animation that defines how an object appears in the game

Race Car

Object

Includes the behaviors or properties How it accelerates when

the gas pedal is pressed

How it stops when the brake is applied

How it turns as the driver rotates the steering wheel

How it screeches when it turns quickly

Sprite

The physical appearance of the car in the game. A picture or animation

that defines what the object looks like in the game

In Game Maker, a game item usually has both an object and a sprite.The object is the behavior and the sprite is the appearance.

Why do we need both?

Having both allows flexibility For example, if we want a character to run and walk

both to the left and the right, we need many images or appearances for this character. The behavior will be the same.

Having the many sprites, all sharing the same object (behaviors), simplifies the designer’s work.

Our behavior – losing health if hit by an enemy – will be the same regardless of our character’s appearance – facing left or right.

Bounding Boxes

A bounding box - a box that is used to estimate the area that a sprite takes up.

Bounding boxes are especially important for checking whether there is a collision between two objects.

When precise collision checking is on, a collision occurs only when a solid, collide-able part of a sprite inside the bounding box is touched. When precise collision checking is off, all pixels in the bounding box are solid and collide-able.

Origin Point

The point in the sprite that corresponds to its position within the room. When you create an instance at a particular x/y position, the origin of the sprite is placed there.

The default origin point is the top left corner of the sprite.

Origin Point continued The default origin point is the top left corner of the sprite but it is

often more convenient to use the center, which can be found easily by clicking the Center button, or some other point on the sprite.

You can set the origin point manually by clicking in the sprite image which will move the cross to the point you clicked, or by inputting different values for x and y in the corresponding boxes in the program. Note that you can even set an origin outside the area of sprite by using negative numbers (for left and up) or positive numbers larger than the sprite width and height (for right and down), which can be very useful when dealing with objects that need to draw composite sprites.

Naming Game Maker requires that every resource (sprite, object,

room, etc.) has its own name. This makes each resource easily identifiable to both the game developer and the game engine.

There is a certain way to name everything we add to our games.

For each thing we add to our game (such as a sprite, object, or background), the first part of the name is the type of thing it is (i.e. object) and the second part of the name is what it is (i.e. main character)

In Game Maker, you can not use spaces in the names. So we put all the words together and capitalize the first letter of each word AFTER the first word. objectMain, spriteChaser, backgroundCoolPic

Room

A level or scene (such as a title screen) in your game Each room has a grid which is not visible to the player.

You set the height and width of all cells in the grid by typing in values (in terms of pixels) in the snap X and Y fields.

When you place an object in the room by clicking, the origin of that object’s Sprite will snap to the nearest intersection on the grid. This makes it easier to place objects in straight lines and directly next to each other.

Events

Things that happen during the course of the game. Some examples would be when the player presses a

key, when an alarm goes off, or when two objects collide.

Actions

Operations that happen in response to an event. Some actions include moving, changing color, or

creating objects.

Events and Actions

In Game Maker, an event is something that occurs in the game, while an action is a response to an event.

For example, when a player presses the right arrow key, that is an event. In response to this event, we designate an action – that a character moves to the right.

Keyboard Event

The Keyboard event is used to create an action when a key is pressed and continue that action until the key is no longer held down.

Another key option is KeyPress. Here an action only happens once when the player hits a key.

Subimages

A subimage is one image or frame of an animated sprite.

Any sprite can have one or more sub images. The game cycles through these subimages in order to animate the sprite.

Subimages are numbered starting with zero, so the first subimage in a sprite is frame0, the second is frame1, and so on.

Align to Grid Align to Grid – this action forces the position of an

object to align to a grid, so that the object stays on the grid and does not get stuck in neighboring objects.

When an object aligns to grid, it moves or snaps to the nearest grid space based on the horizontal and vertical values designated.

Example: If you define a grid of 10 pixels by 10 pixels, it could snap to the nearest position that is a multiple of 10, such as (10, 10), (20,10), (10, 20), (100, 130), and so on.

Relative

Selecting relative will add the specified value to the variable.

In terms of scoring, if the score value is relative, that means that the points well be added to the current score.

Example: If a player’s score is 100, and he/she picks up a prize with a value of 20, the new score will be 120 if relative is checked. If relative is not checked, the score becomes the absolute value of the prize – in the case of this example the score would be 20, even if the played had a score of 150 before getting the prize.

Conditional Statements with the Else Action

In computer science, a conditional statement identifies what the program should perform if a condition is met or is not met.

It works like this – if the condition is met, then perform an action; otherwise (else) perform another specified action.

Sounds Music and sound effects help to make a game

interesting and realistic. To add sound in Game Maker, first obtain a sound file.

WAV files are ideal for sound effects, and MIDI files work well for background music

You can record your own sound using a program such as audacity.

After importing your sound into Game Maker, you can add special effects such as Echo or Reverb.

Sounds can be used for collisions, picking up prizes, and reaching goals.

Variable

In computer science, a variable is a name that keeps track of something. In Game Maker, a variable keeps track of a quantity or value.

In the 2D maze game, we create a variable to keep track of the direction that the main character is facing at any given time. This helps make sure that the main characters’ throw is in the same direction that this character is facing. The variable stores the direction in terms of degree (0° if facing to the right, 180° if facing to the left).

The important thing to remember is that a variable is a name which acts like a storage container and consists of a value which can change.

Test Instance Count

A control action in which you specify an object and a number of instance of that object. This can be used to check whether all instances of a particular type are gone, so that a level or game ends.

Alarm Alarm – a timer that decreases by 1 step, each step

is 1/30th of a second. When you have actions that you would like to do

later or repeat after a certain amount of time passes you can accomplish this with alarms.

Alarms are countdown timers, just like you see on the microwave, at a basketball game, or sitting next to your bed. Once the alarm goes off, it signals the object to take action.

You need to use an action to set your alarm