Thread: Locking up!

Ok, so I did a tutorial on basic animation and then I made a sprite map and altered the program to use the numpad to go in all 8 directions (tut was 4). This all worked just peachy, then I decided to try and alter it again to chase the mouse around the screen, which is does but if it goes to the right or bot of the screen it locks up.

Code:

void SPRITE::HandleEvent(SDL_Event* event)
{
    switch(event->type)
    {
        case SDL_QUIT:
                {
                Running = false;
                break;
                }

        case SDL_MOUSEMOTION:
                {
                MousePosition(event);
                break;
                }

        default: break;
    }
}


bool SPRITE::MousePosition(SDL_Event* event)
{
    int mX = event->motion.x;
    int mY = event->motion.y;

    if(mX != mouseX || mY != mouseY)
    {
        mouseX = mX;
        mouseY = mY;
        return true;
    }
    return false;
}



void SPRITE::ChaseMouse()
{
    int direction = 0;
    int moveX, moveY;

    // is sprite at cursor?
    while( (x != mouseX) || (y != mouseY))
    {
        moveX = ( mouseX - x );
        moveY = ( mouseY - y );

        // decide which direction to move towards cursor
        if(moveX > 0 && moveY > 0)
                    direction = 3;
        else if(moveX > 0 && moveY < 0)
                    direction = 9;
        else if(moveX < 0 && moveY > 0)
                    direction = 1;
        else if(moveX < 0 && moveY < 0)
                    direction = 7;
        else if(moveX > 0)
                    direction = 6;
        else if(moveX < 0)
                    direction = 4;
        else if(moveY > 0)
                    direction = 2;
        else if(moveY < 0)
                    direction = 8;

        // Set velocity and section of spritemap
        switch(direction)
        {
            case 8:  {
                     yVel -= SPRITE_HEIGHT / 63;
                     section.x = 65;
                     section.y = 0;
                     break;
                     }

            case 2:  {
                     yVel += SPRITE_HEIGHT / 63;
                     section.x = 65;
                     section.y = 130;
                     break;
                     }

            case 4:  {
                     xVel -= SPRITE_WIDTH / 63;
                     section.x = 0;
                     section.y = 65;
                     break;
                     }

            case 6:  {
                     xVel += SPRITE_WIDTH / 63;
                     section.x = 130;
                     section.y = 65;
                     break;
                     }

            case 7:  {
                     xVel -= SPRITE_WIDTH / 63;
                     yVel -= SPRITE_HEIGHT / 63;
                     section.x = 0;
                     section.y = 0;
                     break;
                     }

            case 9:  {
                     xVel += SPRITE_WIDTH / 63;
                     yVel -= SPRITE_HEIGHT / 63;
                     section.x = 130;
                     section.y = 0;
                     break;
                     }

            case 1:  {
                     xVel -= SPRITE_WIDTH / 63;
                     yVel += SPRITE_HEIGHT / 63;
                     section.x = 0;
                     section.y = 130;
                     break;
                     }

            case 3:  {
                     xVel += SPRITE_HEIGHT / 63;
                     yVel += SPRITE_HEIGHT / 63;
                     section.x = 130;
                     section.y = 130;
                     break;
                     }

            default: break;
        }
        Move();

        switch( direction )
            {
                case 8: yVel += SPRITE_HEIGHT / 63; break;
                case 2: yVel -= SPRITE_HEIGHT / 63; break;
                case 4: xVel += SPRITE_WIDTH / 63; break;
                case 6: xVel -= SPRITE_WIDTH / 63; break;
                case 7: xVel += SPRITE_WIDTH/63; yVel += SPRITE_HEIGHT/63; break;
                case 9: xVel -= SPRITE_WIDTH/63; yVel += SPRITE_HEIGHT/63; break;
                case 1: xVel += SPRITE_WIDTH/63; yVel -= SPRITE_HEIGHT/63; break;
                case 3: xVel -= SPRITE_WIDTH/63; yVel -= SPRITE_HEIGHT/63; break;
                default: break;
            }

    }
    section.x = 65;
    section.y = 65;
    Move();
}

bool SPRITE::Execute(TIMER& GameTimer, SDL_Event* event)
{
    Running = true;

  if(Initialize() == false)
        {
        return -1;
        }

    while(Running)
    {

        GameTimer.Start();
        SDL_PollEvent(event);
            {
            HandleEvent(event);
            }
       ChaseMouse();


        if( GameTimer.Get_Ticks() < 1000 / FRAMES_PER_SECOND )
            {
            SDL_Delay( ( 1000 / FRAMES_PER_SECOND ) - GameTimer.Get_Ticks() );
            }
        GameTimer.Stop();
    }

    SDL_Quit();

    return 0;
}

void SPRITE::Move()
{
    //Move the sprite left or right
    x += xVel;

    //If the sprite went too far to the left or right
    if( ( x < 0 ) || ( x + SPRITE_WIDTH > SCREEN_WIDTH ) )
    {
        //move back
        x -= xVel;
    }

    //Move the sprite up or down
    y += yVel;

    //If the sprite went too far up or down
    if( ( y < 0 ) || ( y + SPRITE_HEIGHT > SCREEN_HEIGHT ) )
    {
        //move back
        y -= yVel;
    }

    //Fill the screen white
    SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 0xFF, 0xFF, 0xFF ) );
    //Show the sprite on the screen
    Show();
    //Update the screen
    SDL_Flip( screen );
}


void SPRITE::Show()
{
    //Show the sprite    ApplySurface( sprite, section, screen, x, y );
}

This is all the relevant code. I tried changing the right and bot boundries in Move(), but it just locked up farther away from the edge. Being ignorant while learning is such a pain.

Any feedback on the ChaseMouse() and MousePosition() funcs would be cool as well, as these are mostly mine. Please feel free to straighten me out on what I did wrong and how. EDIT:: My commenting is really poor, this is something I need to work on, thanks for your patience.

Code:

    //If the sprite went too far to the left or right
    if( ( x < 0 ) || ( x + SPRITE_WIDTH > SCREEN_WIDTH ) )
    {
        //move back
        x -= xVel;
    }

What happens when x is between SCREEN_WIDTH and SCREEN_WIDTH - SPRITE_WIDTH ?
It gets moved back to its previous position and the condition here:

Code:

    while( (x != mouseX) || (y != mouseY))
    {

will never fail.

Try something like this (assuming x can never be less than 0 or greater than SCREEN_WIDTH-1

Code:

    if( x < 0 )
    {
        x=0;
    }
    if ( x + SPRITE_WIDTH > SCREEN_WIDTH )
    {
        x = SCREEN_WIDTH - SPRITE_WIDTH;
    }

And something similar for y.

Probably because you're moving your sprites in fixed lengths. If something is 1 foot away from you, but you can only take 3-foot steps, how are you going to reach it?

You can upload your files as attachments or use something like pastebin for smaller code segments. If someone was scolded for posting links, it was probably because he was spamming his personal website.