Solo MP

This MP, as well as all other MPs in CS 225, are to be completed without a partner.

You are welcome to get help on the MP from course staff, via open lab hours, or Piazza!

Getting the files

From your CS 225 git directory, run the following on EWS:

git fetch release
git merge release/mp1 -m "Merging initial mp1 files"

If you’re on your own machine, you may need to run:

git fetch release
git merge --allow-unrelated-histories release/mp1 -m "Merging initial mp1 files"

Upon a successful merge, your MP1 files are now in your mp1 directory.

Adding your HSLAPixel class to this project

Before starting this MP, make sure you have finished lab_intro.

Part 1: Create a Makefile

In CS 225, we feel it’s important you understand how a C++ program compiles.

Go through the Makefile Tutorial and create a Makefile for this assignment. You may find the lab_intro Makefile useful as a reference.

Your Makefile must compile together your own solution files, namely main.cpp, mp1.cpp, mp1.h, and files in the cs225 directory. Do not have typos in your file names or your Makefile! For example, make sure your Makefile compiles a file named main.cpp, not a file named main.C or test.cpp or any other such thing.

Please make sure your Makefile does not compile extra files that are not part of this MP. For example, do not add in files from the Makefile tutorial by mistake; the only files the Makefile should be dealing with are the few listed in the paragraph above.

Your Makefile must produce an executable called mp1 (all lowercase).

Hint: Makefile for testing

After creating a Makefile that builds mp1, the following two lines can be added to the end of your Makefile so that you can also build the test cases:

test : unit_tests.o mp1.o PNG.o HSLAPixel.o lodepng.o
	$(LD) unit_tests.o mp1.o PNG.o HSLAPixel.o lodepng.o $(LDFLAGS) -o test

unit_tests.o : tests/unit_tests.cpp tests/catch.hpp cs225/PNG.h cs225/HSLAPixel.h
	$(CXX) $(CXXFLAGS) tests/unit_tests.cpp

Part 2: Rotate an Image

Open mp1.cpp and complete the rotate function. This function must:

Here’s alma.png rotated 180 degrees:



In order to complete this, you will need to make use of CS 225’s PNG class, which you learned about in lab_intro:

Open the doxygen for cs225::PNG
Hint: How Do I Rotate an Image?

Take a piece of paper and draw a 5x5 grid on it. Mark the box at (0, 1). Rotate that paper 180 degrees and note where the marked box is now located. Repeat for other squares if necessary.

Can you find the pattern/formula for how the pixel moves?

Testing Part 2

The Makefile you created in Part 1 must produce an mp1 executable (all lower case mp1). The following command must make mp1:


A main has been provided for you that will call your rotate to read in in.png and output out.png. With that, you may use the given files in_01.png, out_01.png, in_02.png, out_02.png, in_03.png, and out_03.png to test your program. First, copy in_01.png to in.png by typing

cp in_01.png in.png

Then run your program:


Finally, compare the output by opening each file and looking at them or using diff to compare your output to the expected output:

diff out.png out_01.png

If diff exits without any output, then the files are the same! :)

Part 3: Getting Creative

A fellow Illini and CS 225 alumni created a website that now attracts over 30,000 followers that displays randomly generated fusions of color that are both mesmerizing and beautiful. Here are just a few:

Generate Your Own Colored Background

Open up mp1.cpp and complete the myArt function. The myArt function must:

That’s it – everything else is up to you! You are highly encouraged to use gradients, fractals, or other designs in your art. More than anything else, have fun! As an extra bit, course staff will award +1 point to designs that are particularly unique, creative, beautiful, or stand out from other designs.

Finally, you will make use of and see your artwork later in the semester. Make it something you’ll be happy to see. :)

Testing Part 3

The main.cpp provided for you will produce your artwork instead of an image if you run ./mp1 with a command line parameter. If you provide a number after ./mp1, it will save your artwork as art.png. For example:

./mp1 800

Sharing Your Art

You just made something awesome that never existed before -- you should share your art (but do not have to)!

If you share your art on Facebook, Twitter, or Instagram with #cs225, I will or the post as soon as I see it. I think many of your peers will too!   — Wade

Autograder Testing

We have provided a few automated tests that will test your Part 2 code only. You can run a subset of the test cases that will be used in the autograder with the following commands:

make test

Grading and Submission

You must submit your work to git for grading. We will use the following files for grading:

All other flies will be ignored in grading.

Guide: How to submit CS 225 work using git