Question

I am writing a small console adventure game and I faced a few problems.
1. The input is kinda laggy, I’m using while loop ( while(getch() == ‘w’) ). After a key is pressed the first time, nothing happens (you have to press it 2 times) and if you switch directions (press key A/D/S) it also doesn’t react the 1st time. If you hold a key, it works fine. How can this be fixed?

2. Here’s the function I use to refresh game (render the game scene when a key is pressed):

    void refresh(char map[Y][X])
{
    system("cls");
    for (int i = 0; i<UP; i++)
    {
        cout<<endl;
    }
    for (int i = 0; i<Y; i++)
    {
        for (int k = 0; k<LEFT; k++)
        {
            cout<<" ";
        }
        for (int j = 0; j<X; j++)
        {
            cout<<map[i][j];
        }
        cout<<endl;
    }
}

When I use this function once, it’s ok, but when they key is pressed or held multiple times – the game field starts to flash. I figured that I need to redraw only a part of the field (where changes are made/movements are done), not the whole field. Can you offer any ideas how to do that?

The sample code for input:

while(getch() == 'w')
    {
        if (map[y-1][x]!= WALL)
        {
        map[y-1][x] = CHARACTER;
        map [y][x] = ' ';
        y--;
        refresh(map);
        Sleep(SPEED); // this is unnecessary, SPEED is 0, I just kept it for tests
        }
    }

Basically, the main function looks like this:

int main()
{
    (...) Variables (...)
    generateMap(FROM FILE);
    refresh(); // First initialization of the field
    while (getch() != 'q') // While not quitting
    {
    while(getch() == 'w')
    {
        if (THE FIELD ABOVE IS NOT OCCUPIED)
        {
             setSomeVariables();
             refresh(THE GAMEFIELD);
        }
    }
    }
    while(getch() == 's')
    {
        if (THE FIELD BELOW IS NOT OCCUPIED)
        {
             setSomeVariables();
             refresh(THE GAMEFIELD);
        }
    }
    }
    while(getch() == 'a')
    {
        if (THE FIELD ON THE LEFT IS NOT OCCUPIED)
        {
             setSomeVariables();
             refresh(THE GAMEFIELD);
        }
    }
    }
    while(getch() == 'd')
    {
        if (THE FIELD ON THE RIGHT IS NOT OCCUPIED)
        {
             setSomeVariables();
             refresh(THE GAMEFIELD);
        }
    }
    }
    return 0;
}

Answer 1

Don’t use system("cls"), it is really slow, instead set the cursor on the beginning of the screen with the following code:

COORD cur = {0, 0};
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), cur);

You should call getch() only one time in the loop, like this:

char key;

do
{
    key = getch();

    if(key == 'w')
    {
        //do something
    }

    //the other if statements

}while(key != 'q');