Building a Rhythm Game in C

This is the rhythm game I made as a first-year term project.

Making the game itself didn’t take long, but I remember struggling to get the notes in sync.

How to Play

Use the D, F, J, K keys to hit notes.

If you hit a note precisely, the judgment is Excellent. If you hit slightly late, the judgment is Good.

Hitting notes consecutively builds a combo.

Your score increases based on combo and judgment. The scoring formula is:

1

score += (combo / 10 + 1) * 50

In the settings menu you can toggle two options:

• Turning on Note Recording Mode enables an editor mode.
  The music plays but no notes fall. While the song is playing, your key inputs are saved as notes to a file named note.txt.

• Turning on Debug Mode enables debugging.
  You can check the screen refresh delay.

Explanation

• The simple text animation at the start is implemented with a for loop.
  I store the text in a 2D char array and repeatedly print and erase one line at a time.

• When a song is selected, the program reads a text file containing the notes into a char buffer.
  0 means no note, 1 means a note exists.

• The music is played using the PlaySound function.

• Notes are rendered by changing the console text color and printing spaces so they look like rhythm-game notes.
  I change text color with SetConsoleTextAttribute.

• The per-frame delay is matched to the song’s BPM.
  Because notes must be drawn quickly, delay variance is inevitable.
  I measure time at the start and end of each loop and adjust the delay to keep it uniform.

• Using a variation of double buffering, I clear only the regions where the front and back buffers differ (with spaces) and then draw.

• Key input is read with GetAsyncKeyState.
  For multithreading I use _beginthreadex, which allows multiple keys to be registered simultaneously.

• When a note reaches the judgment line, I compare the screen buffer with the current key state to determine the judgment.
  By comparing the states of the front and back buffers, I distinguish hold notes from tap notes.
  If you press exactly on time, it’s Excellent. If you press early, it’s Good. If you miss, it’s Miss.
  A key_state variable prevents holding a key to farm points.

• During gameplay the counts of Excellent, Good, and Miss are recorded.
  A rank is assigned based on their ratios.
  When the game ends it shows the judgments and draws a graph so you can see your performance at a glance.