Plan
Applets
The
Applets & Video Games
Demo on making and running a simple applet from scratch Demo on making and running a simple application from scratch Measurements Frame rates Threads
Video Games
CompSci 4
Applets & Video Games
6.1
CompSci 4
Applets & Video Games
6.2
Applets
Definition
From the Java 5.0 API
An applet is a small program that is intended not to be run on its own, but rather to be embedded inside another application.
Definition Differences from applications Download process Use of html Use of jar files Example
The name Applet is derived from the name Application.
CompSci 4
Applets & Video Games
6.3
CompSci 4
Applets & Video Games
6.4
Applet vs. Application
Applets Run in web browser Often downloaded from untrusted site Restricted from file system access Restricted from outside network communication Applications Run independently Typically obtained through trusted source Allow creation and modifications of files Allow outside network communication Must have a main method
Running an Applet
1.
2.
3.
Load a web page with an <applet> tag embedded in the HTML Load the compiled applet from website to local machine Run the compiled applet on the local machine
CompSci 4
Applets & Video Games
6.5
CompSci 4
Applets & Video Games
6.6
HTML for Applet
<applet code=pong/Pong.class archive=pong.jar width=200 height=200></applet> code is the name of the class that extends JApplet archive is the name of the jar file containing all classes
Jar files
Jar is short for Java Archive Compresses files and directories into a single file Can be executed in compressed format Files and directories can be extracted Can contain any combination of source code, byte code, and other files
CompSci 4
Applets & Video Games
6.7
CompSci 4
Applets & Video Games
6.8
Demo
Applet Demo Make an applet in Eclipse Make the html in composer Save both to network drive View from the web Application Demo Make an application in Eclipse Run in Eclipse
Video Games
Simulation Measurement units Discrete/Continuous Monitor frame rate limitation Model frame rate limitation User interaction rate Threads overview
CompSci 4
Applets & Video Games
6.9
CompSci 4
Applets & Video Games
6.10
Video Game as Simulation
Video games are simulations of the real world and worlds that do not exist. These simulations are built for our pleasure, but may serve other purposes as well. Examples Flight simulator Oregon trail Pinball
Measurement Units
Initial in setup coordinate system with origin at top left and (1, 1) at bottom right
Allows simple scaling to varying screen resolutions Can be done hierarchically
Distances in pixels Time in seconds Velocity in pixels/second
CompSci 4
Applets & Video Games
6.11
CompSci 4
Applets & Video Games
6.12
Discrete vs. Continuous Time
Discrete Used to approximate continuous Simple conceptually for good rough estimates Causes problems when modeling continuous functions with too coarse grain estimates Continuous Requires abstract representation or infinite precision Requires analytical reasoning Conceptually difficult to model directly
Monitor Frame Rate
Why 75-85 Hz (Frames/second)?
Because we dont actually visually process continuously
Smooth fast movement?
Consider a rate of 1 pixel a second would take more than 8 seconds to move across the screen.
For fast movement there must be jumps in location.
CompSci 4
Applets & Video Games
6.13
CompSci 4
Applets & Video Games
6.14
Model Frame Rate
Model is continuous. Frame rate is discrete. The granularity of frame rate is too coarse for our continuous model. How do we solve this problem? Two separate rates:
User Interaction Rate
Devices such as the keyboard and mouse must also be polled at regular intervals. At what rate should they be polled? Depends on: Available compute power
Monitor frame rate Model frame rate
In contention with monitor frame rate In contention with model frame rate
Which thread has priority
CompSci 4
Applets &a...