4/29/14 CS 1110 Spring 2014: MVC and Games 1

4/29/14 A Standard Game Application
Controller
while-loop
Check for user input
Process user input
Update the models
Event
Loop
Update display/view
No change to models
View
Must We Write this Loop Each Time?
while program_is_running:
# Get information from mouse/keyboard
# Handled by OS/GUI libraries
controller.update()
controller.draw()
Method calls
for loop body
# Draw stuff on the screen
# Handled by OS/GUI libraries
• No: make this
loop part of the
library!
• Then we only have
to provide the
controller class.
Controller
Subclass of Game
Attribute view
(inherited)
Purple because it’s
also partly a View
Model
Subclasses of GObject
View
Method
Class GView
GObject.draw
• GEllipse, GImage, …
• Handles details of
• Comprises many objects
drawing
• Knows how to draw
• Provided in Game
CS 1110 Spring 2014: MVC and Games while program_is_running:
# Get information from mouse/keyboard
Would like to
# Handled
“plugby
in”OS/GUI
code
libraries
# Code to respond to user input Why do we need to
write this each time?
# Code to draw stuff in the window
# Get window onto the screen
# Handled by OS/GUI libraries
Model-View-Controller Pattern
Division
can apply
to classes
or modules
Calls the
methods or
functions of
Controller
• Updates model in
response to events
• Updates view with
model changes
Model
• Defines and
View
• Displays model to
manages the data
• Responds to the
controller requests
Model-View-Controller in A5
Other attributes
(defined by you)
Must We Write this Loop Each Time?
the user
• Provides interface
for the controller
Example: Animation
class Animation(Game):
See animation.py
"""Application to an ellipse in a circle."""
def init(self):
"""Special loop initialization method."""
… Loop initialization
Do NOT use __init__
def update(self, dt):
"""Change the ellipse position."""
…
Loop body
def draw(self):
"""Draw the ellipse"""
Use method draw()
…
defined in GObject
1 4/29/14 Example: Animation
What Attributes to Keep: Touch
class Animation(Game):
See animation.py
"""Application to an ellipseParent
in a circle."""
class that handles details
def init(self):
"""Special loop initialization method."""
… Loop initialization
Do NOT use __init__
def update(self, dt):
"""Change the ellipse position."""
…
Loop body
def draw(self):
"""Draw the ellipse"""
Use method draw()
…
defined in GObject
More Attributes: Checking Click Types
•  Double click = 2 fast clicks
•  Count number of fast clicks
pressed
released
released
Mouse button pressed
§  last not None, touch None:
Mouse button released
§  last and touch not None:
Mouse dragged (button down)
time
See touch.py
§  Ball countdown vs. serve
State ANIMATE_CIRCLE
§  Implemented as an int
See state.py
Types of Models for Assignment 6
•  Often subclass of GObject
sparks
§  Has built-in draw method
§  See documentation in A6
§  Ball countdown vs. serve
•  Includes groups of models
§  Method update() checks state
§  Executes correct helper
§  Implemented as an int
State ANIMATE_HORIZONTAL
§  State is an enumeration; one of several fixed values §  Global constants are values
•  Add an attribute state
§  State is an enumeration; one of several fixed values State ANIMATE_CIRCLE
§  Executes correct helper
§  Playing game vs. pausing
•  How do we store state?
See touch.py
•  Add an attribute state
State: Changing What the Loop Does
•  State: Current loop activity
Previous
Touch
State: Changing What the Loop Does
•  How do we store state?
§  Set to 0 when mouse released
§  Check time when next pressed
§  last None, touch not None:
Current
Touch
§  Method update() checks state
pressed
§  Add an attribute time
§  Increment when not pressed
(e.g. in loop method update())
•  Compare touch, last position
Line segment = 2 points
§  Playing game vs. pausing
§  Reset to 0 if not fast enough
•  Time click speed
§  The mouse press position
§  Or None if not pressed
§  Use self.view.touch inside
controller (Game) methods
•  State: Current loop activity
Is it fast enough?
§  Add an attribute clicks
•  Attribute touch in GView
State ANIMATE_HORIZONTAL
Importance of class invariants
See state.py
§  Global constants are values
CS 1110 Spring 2014: MVC and Games § 
§ 
§ 
§ 
Example: rockets in pyro.py
Each rocket is a model
But so is the entire list!
update() will change both
rocket
•  A5: Model class
§  Container, like A4 Dataset
§  Holds bricks, ball, paddle
See pyro.py
2

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