Planets!
Homework #1, CSCI 322
Description: I have placed an animated planets demo in Racket in the class repo called planets00.rkt.
Currently it uses no explicit threading, the animation loop uses busy waiting when there is no animation, and it uses sleep/yield in order to collaborate with the GUI. Create two new versions of this
program:
1. A program called planets01.rkt that uses a single thread for the animation loop: calculate
forces, move, refresh the view, sleep, repeat. Clicking the checkbox should suspend and resume
this thread. There should be no busy waiting when the animation is suspended. Use yield
instead of sleep/yield.
Also add a button that will kill the program. Remember to kill the animation thread, too!
2. A program called planets02.rkt uses a new thread for each new planet. Each thread will take
care of calculating the forces and updating the position of its own planet. Every time the mouse
is clicked, a new planet and a new thread are created. The threads can be kept in a separate list,
or each planet object can contain its own thread.
There should be one more thread that takes care of refreshing the view (there’s no point in each
planet refreshing the view). Note that the view refreshing does not have to happen at the same
frequency as the planet updating. For example, given enough cycles, we can update the planet
positions more frequently than we refresh the view, to get a more accurate simulation.
Clicking the checkbox suspends and resumes all of these threads. Again, no busy waiting and no
sleep/yield. And include the kill button. Kill all threads!
Due date: Friday, January 23, at midnight. Remember to upload both programs. Each should be standalone and run without the other. 50% of this assignment’s grade points for each stage.
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