Description
Provided Files
● main.c
● myLib.c
● myLib.h
Files to Edit/Add
● main.c
● myLib.c
● myLib.h
● Makefile
● .vscode
○ tasks.json
Instructions
Note: Make sure to copy over your Makefile and .vscode/tasks.json from one of your
previous assignments.
TODO 1.0
● void drawRect(int col, int row)
○ Complete this function in myLib.c (right under the setPixel function).
You should already know how to do this from your last lab, and it
should for a filled in rectangle.
○ In main.c, find and uncomment UNCOMMENT #1. You should see a
yellow rectangle in the bottom half of the screen.
TODO 2.0
● void fillScreen(unsigned short color)
○ Head back to myLib.c, find fillScreen (right beneath drawRect) and
complete it.
CS 2261 Spring 2021
○ You may only use a single loop (one for-loop) to complete this one.
■ Hint: the GBA screen has a total of 240 x 160 pixels which is
equal to 38400.
○ Enter main.c and uncomment UNCOMMENT #2. The background of
your game should now be a beautiful shade of blue, and you should see
two new rectangles. There should be one green “land” rectangle at the
bottom of the screen, and one white “cloud” rectangle towards the top
of the screen that moves horizontally. There should also still be the
yellow rectangle in the center of the screen.
TODO 3.0-3.2
This one requires a lot of moving parts to work, so it is broken into three parts.
● TODO 3.0
○ Open myLib.h, find the button macros, and complete them.
○ For BUTTON_PRESSED, assume that buttons and oldButtons have been
set up appropriately.
● TODO 3.1
○ Since buttons and oldButtons haven’t been set up correctly (yet!), head
on back to main.c and initialize them in the initialize function.
○ They have already been declared in main.c (and in myLib.h as extern
variables), so you don’t have to worry about that part this time, but you
will when you code things yourself for your homeworks.
● TODO 3.2
○ The buttons still won’t do anything unless you update them each frame,
so do that in the main while-loop.
○ After you have completed these tasks, find UNCOMMENT #3 in the
update function and do the thing.
○ Run it, and now you can press button A to toggle the clouds between
white and gray, as if they are switching between light, fluffy white
clouds and gray clouds preparing for rainfall.
○ Holding down the A button for a long time should have the same effect
as just tapping it a single time. If that is not the case, you did one of these
three TODOs incorrectly.
TODO 4.0
● Now that you can take button input, find TODO 4.0 in the update function and
complete it so that the yellow rectangle can move up, down, left, and right if
CS 2261 Spring 2021
you press the corresponding arrow key.
○ This time, it should move for as long as the key is held, meaning that if
you tap it once quickly, it will barely move, but if you press it for several
seconds, it will move a lot. If not, fix that.
● Compile and run, and you should be able to move the yellow rectangle
anywhere on the screen.
TODO 5.0-5.2
This is the most exhaustive part of the lab, but also the most important.
● TODO 5.0
○ At the bottom of myLib.c, implement the collision function. It takes in
the positions and dimensions of two rectangles, and returns a 1 if they
are colliding, or a 0 if not.
■ Hint: using graph paper, or drawing a grid yourself, is extremely
useful. This function should work regardless of the size or
velocity of the rectangle (if one is moving).
● TODO 5.1
○ Now that you have the collision function implemented, use it in the
update function. If the yellow rectangle collides with the moving cloud
rectangle, reset the yellow rectangle’s position to where it was first
initialized (refer to the initialize function to see the exact location).
Also, make the cloud rectangle stop moving (the cloud’s horizontal
velocity variable is cCDel) if it’s moving. If the cloud is not moving, make
it start moving horizontally to the right side of the screen.
● TODO 5.2
○ Now use the collision function to account for if the yellow rectangle
collides with the land rectangle. Additionally, if lColor (the land’s
current color) is green, change it to black. If it is already black, change
it to green.
■ Hint: you can refer to the logic that was used to make the clouds
change colors when you press A.
○ Compile and run. Verify that it runs correctly, and then you are done.
● Hint: since there are two separate rectangles for which you need to detect a
collision, you’ll need to use the collision function two separate times.
CS 2261 Spring 2021
You will know if it runs correctly if you can:
● Move the yellow rectangle using the arrow keys.
● Press A to change the cloud color from white to gray, and vice versa.
● Make the yellow rectangle collide with any of the other rectangles and be
transported to its initial position.
● Collide with the land rectangle at the bottom, changing the color from black to
green, or vice versa.
● Collide with the moving cloud rectangle at the top, making the cloud stop
moving or start moving to the right side of the screen.
Tips
● Start early, and attend recitation.
● Use graph paper and draw pictures to conceptualize what is happening.
● Follow each TODO in order, and only move forward if everything is correct.
Submission Instructions
Zip up your entire project folder, including all source files, the Makefile, and
everything produced during compilation (including the .gba file). Submit this zip on
Canvas. Name your submission Lab02_FirstameLastname, for example:
“Lab02_KingDedede.zip”.
