14. ESC to exit

We have the skeleton for a game, but ge must "kill the task" using the operating system if we want to finish. That is not very friendly, so let's improve it.

Now we want to be able to quit if we press "Esc". That means barely a couple of changes: on one side, we will not repeat using "while (1==1)", but use a "boolean" variable, whose value might change inside the game loop:

bool gameFinished = false;
 
// Game Loop
while( ! gameFinished )
 

Also, we will check a new key (Esc) and, if pressed, we will change the value of that boolean variable:

if (SdlHardware.KeyPressed(SdlHardware.KEY_ESC)) 
    gameFinished = true;

So the whole program would look like this:

/*
  First mini-graphics-game skeleton
  Version B: ESC to exit the program
*/
 
using System;
 
public class Game02b
{
    public static void Main()
    {
        bool fullScreen = false;
        SdlHardware.Init(800, 600, 24, fullScreen);
 
        Image dotImage = new Image("dot.bmp");
        Image enemyImage = new Image("ghostGreen.bmp");
        Image pacImage = new Image("pac01r.bmp");
 
        int x=40, y=12;
        int pacSpeed = 6;
 
        int amountOfDots = 100;
        int[] xDot = new int[amountOfDots];
        int[] yDot = new int[amountOfDots];
        bool[] visible = new bool[amountOfDots];
 
        Random randomNumberGenerator = new Random();
        for(int i=0; i<amountOfDots; i++)
        {
            xDot[i] = randomNumberGenerator.Next(0,760);
            yDot[i] = randomNumberGenerator.Next(40,560);
            visible[i] = true;
        }
 
        int amountOfEnemies = 4;
        float[] xEnemy = { 150, 400, 500, 600 };
        float[] yEnemy = { 100, 200, 300, 400 };
        float[] incrXEnemy = { 5f, 3f, 6f, 4.5f };
 
        int score = 0;
        bool gameFinished = false;
 
        // Game Loop
        while( ! gameFinished )
        {
            // Draw
            SdlHardware.ClearScreen();
            //Console.Write("Score: {0}",score);
 
            for(int i=0; i<amountOfDots; i++)
            {
                if (visible[i])
                    SdlHardware.DrawHiddenImage(dotImage, xDot[i], yDot[i]);
            }
 
            SdlHardware.DrawHiddenImage(pacImage, x, y);
 
            for(int i=0; i<amountOfEnemies; i++)
                SdlHardware.DrawHiddenImage(enemyImage, 
                    (int)xEnemy[i], (int)yEnemy[i]);
 
            SdlHardware.ShowHiddenScreen();
 
            // Read keys and calculate new position
            if (SdlHardware.KeyPressed(SdlHardware.KEY_RIGHT)) x+=pacSpeed;
            if (SdlHardware.KeyPressed(SdlHardware.KEY_LEFT)) x-=pacSpeed;
            if (SdlHardware.KeyPressed(SdlHardware.KEY_DOWN)) y+=pacSpeed;
            if (SdlHardware.KeyPressed(SdlHardware.KEY_UP)) y-=pacSpeed;
 
            if (SdlHardware.KeyPressed(SdlHardware.KEY_ESC)) 
                gameFinished = true;
 
            // Move enemies and environment
            for(int i=0; i<amountOfEnemies; i++)
            {
                xEnemy[i] += incrXEnemy[i];
                if ((xEnemy[i] < 1) || (xEnemy[i] > 760))
                    incrXEnemy[i] = -incrXEnemy[i];
            }
 
            // Collisions, lose energy or lives, etc
            for(int i=0; i<amountOfDots; i++)
                if ((x == xDot[i]) && (y == yDot[i]) && visible[i])
                {
                    score += 10;
                    visible[i] = false;
                }
 
            // Pause till next fotogram
            SdlHardware.Pause(40);
        }
    }
}