Backgrounds, Inheritance in GameMaker BrickMania 1 of 2 - PowerPoint PPT Presentation

Title: Backgrounds, Inheritance in GameMaker BrickMania 1 of 2


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Backgrounds, Inheritance in GameMaker (BrickMania
1 of 2)

• Foundations of Interactive Game Design
• Professor Jim Whitehead
• January 28, 2008

Creative Commons Attribution 3.0creativecommons.
org/licenses/by/3.0
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Upcoming Assignments

• Wednesday Game Concept Document
• A compelling document that sells your game
  concept
• Title page
• Title of game, name of group, name of team
  members, sample artwork
• Overview page
• Table at top game genre, platform (PC/GameMaker,
  PC/RPG Maker, etc.), team size
• Key points section
• Bulleted list of important elements of gameplay
• Goal of game, what makes game unique, main
  characters, main fictional elements
• Sample artwork image to give feel of the game
• Biographies
• True, pocket biographies of each team member (1-2
  paragraphs each) stressing experience that makes
  you a strong game designer
• 1-3 pages giving a textual description of the
  game
• Fictional background, brief description of
  characters, goal of player in game, how does
  player interact with the game, brief description
  of levels, game audience, other important
  elements as needed.
• 1-2 pages of sample conceptual artwork
• Hand-drawn sketches are fine
• Start early!

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Upcoming Assignments

• Friday midterm exam
• Will give list of study questions in class
  Wednesday
• Mostly based on lectures, but will also draw on
  material in the readings, especially Rules of
  Play
• Test is mostly short answer
• Make sure you arrive on time
• Some questions will concern a game demonstration
  given at the start of the exam
• You do not need a test booklet exam will
  contain enough space to answer questions

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Announcements

• www.soe.ucsc.edu/classes/cmps080k/Winter08/
• Has syllabus, assignment descriptions, exam days,
  final exam time, link to gamelog site, links to
  tool descriptions, and more
• Porter Video Games Tournament
• Cancelled due to weather. Will be rescheduled.
• Will keep you posted.
• Game club announcement
• Meet Thursdays, 215pm
• Conference room A
• Go in entrance next to Express It

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Announcements (2)

• Help for making your Mac dual boot
• Contact Ian Rickard to arrange help time
• inio_at_soe.ucsc.edu
• Weekly help session for CS 20 (C and XNA Game
  Studio Express)
• Thursday, 430-7pm
• Engineering 2, room 399 (third floor, by
  elevators)
• Starts this week

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Lets create a simple Breakout game

• Game elements
• Background
• Ball
• Paddle
• Score
• Lives
• 3 brick types
• Playfield issmaller thanscreen

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Backgrounds

• Background
• Represents a static background image
• Defined separately, then combined with a room
• Can move, or be motionless
• Many uses
• Moving starfield
• Create starfield bitmap image
• Define as background
• Have it move backwards creates sensation of
  motion
• Image surrounding playfield of game
• BreakMania uses a background this way

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Detecting edges of background

• Reduce boundary objects
• In tile-based games, need many tiles to create an
  interesting level
• With objects, would need separate object for each
  tile type
• Can slow a game down
• Instead, create background image
• Then, use single, invisible boundary object for
  collision detection
• Can be easier to create background in drawing
  program
• Then, just use simple shapes for collision
  detection
• May be easier than converting to tiles at times

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Creating a Background

• Resources -gt Create Background
• Enter name
• Can have a transparent color
• Useful for multi-depth scrolling background
• Load backgroundimage
• Select file

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Break Mania Background

• Created usingThe GIMP
• Free software
• PC Mac
• Used fills text effectsthat comewith GIMP

score box
playfield
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Create Room

• Resources -gt Create Room
• Click on Settings Tab enter name of Room

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Add Background to Room

• Unselect Draw background color
• SelectVisible whenroom starts
• Use pull-downmenu toselectbackgroundimage

Select grid size to match size of sprites for
us, 10x10 works well
Note grid alignment with background image
boundaries need to plan ahead for this!
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Create Sprites

• For BreakMania need sprites for
• Paddle
• Ball
• Three brick types
• Small paddle (for lives display)
• Three different wall types
• Two different vertical (10x50,10x30), one
  horizontal (10x50)
• Used to create invisible barrier for edge of
  playfield
• Game over text

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Create Objects

• For most of the sprites, need to create an
  associated object
• Resources -gt Create Object
• Solid Paddle, three brick objects, three wall
  objects
• Not solid Ball, game over
• No need to create small paddle object
• Only need to use the sprite for lives display
• For now, no behavior
• Will add soon

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Create Invisible Objects

• Three wall types all must be invisible
• Will place them over the background
• Ball will collide with invisible wall objects
• To player, will seem like collision with
  background

Wall objects placed at edge of black playfield.
Show with dotted lines to represent being
invisible during gameplay
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Making Objects Invisible

• Click on visible toggle
• If no check, is invisible

Make solid for bounce behavior
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Place Objects in Room

• Click on game room, then objects tab
• Use pulldown menu to select object to place
• Invisiblewalls
• Bricks
• Paddle
• Ball

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Ball Behavior

• When ball is created, want it to start moving
  upwards at an angle
• Use create event on ball
• Start moving in direction
• Click two up diagonal arrows
• Speed of 10

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Paddle Behavior - Movement

• Left arrow moves left, right arrow moves right
• Up/down arrows stop
• Use keypress events for these

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Paddle Behavior Ball Collision

• Ball should bounce after hitting paddle

Drag-n-drop bounce to actions
Pick collision event, then select ball from
pull-down menu that appears
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Wall Behavior

• If paddle collides with wall, paddle stops
• If ball collides with wall, want it to bounce
• Could define this separately on all three wall
  types
• Tedious
• Error-prone, since every change needs to be
  copied over to the other two walls
• Would be nice if this could be stated once, for
  all walls
• Use object inheritance

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Inheritance

• Objects can have a parent
• All of the behaviors of the parent are copied to
  its children
• Imagine a wall-mother object
• A collision event with the ball causes the ball
  to bounce
• Now, make all three invisible walls have
  wall-mother as a parent
• All invisible walls now collide with the ball
  like the mother!
• By defining one wall-mother object, avoids
  cut-and-paste of collision behavior to three
  invisible walls.
• Note that it is possible to change inherited
  behavior on children
• Just define the specific event a different way.
  Childs definition always trumps that of the
  parent.

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Creating Wall-Mother
Make ball bounce off walls
No sprite, since were using this just for
behavior. Leave it to children to specify exact
visual shape.
Dont set visible, do set solid, since thats
what children should be. Visible doesnt matter
for wall-mother, since it has no sprite
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Now, set parent of invisible walls
Note no events or actions. It gets these all from
its parent, wall-mother!
Set parent to wall-mother using pull-down menu
here
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Brick behavior

• If a ball hits a brick
• It should disappear
• Small ring effect
• Play sound
• Ball should bounce
• Score should go up
• Three brick types
• Use inheritance from new brick-mother
• Put collisionbehavior on mother
• Reuse on all bricks
• Set each colored bricks parent to brick-mother

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Ball Bouncing Off Brick

• The collision of brick with ball is on
  brick-mother
• But, we want the ball to bounce, not the brick
• How to do this?
• Each collision is between two objects
• The object hosting the collision event
• The other object
• In this case, the brick is hosting the
  collision, the ball is the other
• To indicate ball should bounce,select other in
  bouncedialog box

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Making Brick Disappear

• Each brick on screen is an instance of a brick
  object
• Can think of the object as a kind of mold that
  can stamp out many different instances of the
  object
• Brick object mold individual bricks
  instances
• To make brick disappear
• Destroy the instance
• On tabmain1

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Creating Brick Ring Effect

• On draw tab, select Create Effect button

Add offset so ring emerges from center of the
brick
Click relative so ring emerges from brick, not
upper left corner of screen!
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