snake

A fairly straight-forward program, primarily for the purpose of learning a bit about ncurses. full code available here.

ncurses

Four ncurses windows are created;

• a small box containing information
• the border for the bottom portion of the screen
• two windows that sit inside the lower border and can be swapped

The halfdelay setting is used to implement a basic game loop. If a set amount of time has passed then the loop will no longer wait for an input from the user and enter the loop body.

timing issues

There are two isues arise in terms of timing:

• By handling the game loop in this way (using halfdelay), the game can be sped up by pressing any button.
• The snake travels faster in the y-axis than the x-axis due to the non-square nature of the characters.

The first issue can be solved by simply using a proper game loop, but the second is more complex.
One potential solution is to store the snakes head position as a float and update the body/check for collision only when the head crosses an integer boundary. This introduces its own flaws as the snake will now appear to move slower along the y-axis due to the lower visible update rate. This method also depends on the font size matching the update increments properly to achieve the desired effect.

The other solution is, of course, to use something other than ncurses.

program state

The program keeps track of its current status and updates its logical state accordingly.
Starting in the MENU state, the player is shown a short description of the rules and controls. Pressing the spacebar will change to the RUNNING state.
The snake body is represented by a deque. On every frame, the current head position is pushed onto the front of the body before being moved. Then the body length is checked and a body segment is popped from the back end to keep the snake below the maximum length. This gives the appearence that the snakes body is moving but without having to update each body segment.
The game also ensures that a set number of food objects exist at any given time. If the head of the snake occupies the same grid cell as a piece of food then it is removed, and the snake maximum length (and score) is increased by 1. If the head of the snake collides with its body or a wall then the game state is advanced to GAME_OVER and the player is presented with their score, and the option to start a new game.
The player also has the option to pause the game at any time. While in the PAUSED state, the game state is not updated and the word PAUSED is displayed using the secondary lower window. upon unpausing the secondary window is cleared and the game resumes.

pointer lifetime

Additionally, I have used a class to manage the lifetime of the ncurses window pointer. This is probably unnecessary, however this knowledge could potentially be useful in the future.

For the window class, both copy constructor and copy assignment operator have been delete‘d as to avoid multiple ownership of the window pointer. The move assignment operator swaps the window pointers of each object in order to ensure proper deletion of the pointer, and the move constructor uses copies the pointer over and sets the old window pointer to nullpte.
The destructor only operates on a non-nullptr, first clearing the window before calling delwin.

I have also written an member function to enable casting from my class to the underlying WINDOW * for drop-in use in ncurses functions. Again, this is probably unnecessary and for such a simple data structure I could have probably managed the pointer manually.

destruction order

In addition to the WINDOW * wrapper, a second class is required to ensure endwin is only called after all the window destructors have been executed.
This works as the destructor for each object is called (as the leave scope) in the reverse order than that in which they were created. As long as the main ncurses wrapper is constructed before any of the windows (which is will be as it is also responsible for calling initscr) then it will also be the last to be destructed.