Lab 8: DS4Maze -- Part 1 Solution

NOTE: This is a 2 week lab. A working program with parts 1A and 1B below is due before the beginning of lab next week (during a mentor/TA’s office hours). Demonstration to a mentor/TA for the first part ​will be required during their office hours​before the beginning of next week’s lab so it is important to work hard in this lab session.

The lab report will be due in two weeks.

Objectives:

    • Practice Top-Down Program Design, Problem Solving in C

    • Work with 2-dimensional arrays

    • Develop skills in handling events in a loop

Starting Point:

    • lab8.c

To compile your code you will need to append -lncurses to your gcc command line gcc -o lab8 lab8.c -lncurses

Process:

Creating a New Folder

Create a new folder named ​lab8 ​in your ​cpre185labs ​folder on the U: drive. You will want to copy over ds4rd.exe to the ​lab8 ​folder.

Problem Overview

In this and the following lab, you will develop a simple, real-time game controlled by the DualShock 4.

    1. Create a random maze of characters on the screen. The variables COLS and ROWS will indicate the size of the window when it is started. To get the right size window screen, right click on the title bar in Cygwin and select Options>Window and change the columns and rows to match your COLS and ROWS setting in the starting code.

    2. Start your avatar (a single character) at the top center of the screen. ​A function that lets you write a character to any character location in the window is included in the starting source code. ​DON’T CHANGE

THE FUNCTION.
    3. Every so often (a delay to be found by you), the avatar will fall one line down the screen.

    4. Character movement

        1. If the DualShock 4 is tilted right, the avatar will move to right.

        2. If the DualShock 4 is titled left, the avatar will move to the left.

        3. You may need to worry about a tolerance value here.

    5. The avatar may not move into locations occupied by the maze or off of the screen.

    6. The avatar wins if it makes it to the bottom of the screen without getting stuck.

There are three fundamental things to worry about in any game: the game state, the rules, and how to update the game state based on user input. We will begin with the game state in this lab and worry about implementing most of the updating and rules code in the following lab. The game state consists of:

    1. The maze layout

    2. The avatar's location

Ncurses and Screen Layout

For this lab we will use the ncurses library. This library allows us to imagine the screen as a grid of y, x (yes y then x not x,y) coordinates. Y represents the vertical axis and x represents the horizontal axis. The library defines the top left of the screen as 0,0. The point just below the top left of the screen will be 1,0 and the one after that will be 2,0 and so on.

While using the ncurses library, printf() will not work as expected. Instead the special ncurses functions have to be used to write data out to the screen. There is a whole family of calls but the one that you should use mostly in this lab is mvaddch(int y, int x, char c)​. This stands for move add character. This will move the cursor of the specified position on the screen and print character c there.

Part 1A: Develop the Maze

You will generate a random maze of characters in a two dimensional array. This will be the same maze that you output to the screen. Using good modular programming techniques, generate the maze and display it on the screen.

The rand() function in stdlib.h will be very useful, as it will return a new random int every time it is called that is from 0 to a very large number. HINT: Taking
rand's output % 100 may be useful.

To allow for differing levels of difficulty, your code will be given a difficulty value of 0-100 on the command line. This difficulty is the probability in percent that a given space of the maze will be an obstacle. Hence, difficulty zero indicates a blank maze while 50 indicates that roughly half of the characters will be blank.

Part 1B: Character Movement

The second part of the state is the avatar's position. In a loop, you will make the character begin at the top center of the screen and move downward every so often. Note that if you do this without a delay, the program will complete so fast that you can barely see the avatar move.

To add delay, remember that if the -t option is given to ds4rd.exe, the first argument is the time in milliseconds since the executable starts. Use this data to wait some number of milliseconds (a delay for you to determine), and then implement the avatar moving down the screen with the delay.

Demonstration of Parts 1A/1B due before the beginning of next week's lab during the TA’s office hours. A functioning program showing Parts 1A/1B is required for the checkoff.

PARTS 2A/2B coming next week.

Turn-In:

    • No report is due until after next week’s lab.

    • Demo

        ◦ Generate and draw maze

        ◦ Draw avatar

        ◦ Move down screen with delay