Riddle me this programmers

[James]

This is a part of my pong game (the function that controls the movement of the paddle).
Initially I had it operating using the vkup & vk_down arrows. Everything worked correctly. Now I would like to add an additional feature that allows the user to also use the mouse POS to control the paddle.

Here is my function:

void movePaddle()
{
    POINT myMouse;

    //NOTE 0x8000 - Determines that the key is pressed instantly (realtime)
    //So there is no delay

    ///////////////////////////////////        Use Keyboard to control paddle

    if(GetAsyncKeyState(VK_UP) & 0x8000)
    {
        if(player_t.position.top > 0)
        {
            player_t.position.top += ((player_t.myPos.y - 1) - paddleSpeed);
            player_t.position.bottom += ((player_t.myPos.y - 1) - paddleSpeed);
        }
    }

    //Move paddle down
    else if(GetAsyncKeyState(VK_DOWN)& 0x8000)
    {
        if(player_t.position.bottom < screenHeight)
        {
            player_t.position.top -= ((player_t.myPos.y - 1) - paddleSpeed);
            player_t.position.bottom -= ((player_t.myPos.y - 1) - paddleSpeed);
        }
    }

    ///////////////////////////////////        Use mouse to control paddle
    ////Move paddle up
    if(GetAsyncKeyState(VK_LBUTTON))
    {
        if(player_t.position.top > 0 && GetCursorPos(&myMouse) < player_t.position.top)
        {
            player_t.position.top += ((player_t.myPos.y - 1));
            player_t.position.bottom += ((player_t.myPos.y - 1));
        }
    }
    //Move paddle down
    else if(GetAsyncKeyState(VK_LBUTTON))
    {
        if(player_t.position.bottom < screenHeight && GetCursorPos(&myMouse) < player_t.position.bottom)
        {
            player_t.position.top -= ((-player_t.myPos.y - 1));
            player_t.position.bottom -= ((-player_t.myPos.y - 1));
        }
    }
} 

Currently the keyboard still works fine, however the mouse ONLY controls the paddle upwards. if I comment out the first if() statement for the mouse, then the paddle moves downward fine so I know my code is correct, however if I uncomment and I have both statements available (if() & else if()) it breaks it and it only moves upwards. I tried combining the 2 into 1 and it still doesn't work.

if(GetAsyncKeyState(VK_LBUTTON))
{
        if(player_t.position.top > 0 && GetCursorPos(&myMouse) < player_t.position.top)
        {
            player_t.position.top += ((player_t.myPos.y - 1));
            player_t.position.bottom += ((player_t.myPos.y - 1));
        }

        else if(player_t.position.bottom < screenHeight && GetCursorPos(&myMouse) < player_t.position.bottom)
        {
            player_t.position.top -= ((-player_t.myPos.y - 1));
            player_t.position.bottom -= ((-player_t.myPos.y - 1));
        }
} 

Any ideas?? I'm pretty sure my code is correct.

[TechTree]

MSDN tells us that GetCursorPos returns a BOOL and not actual coordinates. The coordinates are placed in an out parameter of type POINT.

So that means that this statement:

if(player_t.position.top > 0 && GetCursorPos(&myMouse) < player_t.position.top)

Is comparing the result of GetCursorPos (which will most likely be TRUE) to player_t.position.top (which is part of a RECT struct and is of type LONG). This comparison will not work as expected:

A BOOL set to true may technically be anything BUT zero. Most likely it is going to be 0xFFFFFFFF which is quite a big positive(if interpreted as unsigned int) or negative (if interpreted as a signed int) number.

I suggest using the coordinates it places into the struct you give it (myMouse in this case) in the check instead of the returned variable.

[James]

Thanks for the info. You're right, I was under the impression that GetCursorPos() returned the value for x,y coords, but it is just a bool ha. Anywho, here is what I currently have.

if(GetAsyncKeyState(VK_LBUTTON))
    {
        
        if(player_t.position.top > 0 && myMouse.y > player_t.position.top)
        {
            player_t.position.top += ((player_t.myPos.y - 1));
            player_t.position.bottom += ((player_t.myPos.y - 1));
        }
        
        else if(player_t.position.bottom < screenHeight && myMouse.y > player_t.position.bottom)
        {
            player_t.position.top -= ((-player_t.myPos.y - 1));
            player_t.position.bottom -= ((-player_t.myPos.y - 1));
        }
        
    } 

When I compile, the paddle only moves upward & not downward, however if I comment out this part :

if(player_t.position.top > 0 && myMouse.y > player_t.position.top)
        {
            player_t.position.top += ((player_t.myPos.y - 1));
            player_t.position.bottom += ((player_t.myPos.y - 1));
        } 

and change the else if() to if() then it moves the paddle down fine.

Bah..... brain fart!!!

Edit:
If the full source is required, it can be grabbed here: http://x-null.net/myPong/myPong4.zip (latest version)

[James]

Got it sorted. Here is my end result:

if(GetAsyncKeyState(VK_LBUTTON))
{
        GetCursorPos( &myMouse );
        ScreenToClient( hWnd, &myMouse);

        if(player_t.position.top > 0 && (myMouse.y < player_t.position.top))
        {
            player_t.position.top += (player_t.myPos.y -(10));
            player_t.position.bottom += (player_t.myPos.y -(10));
        }
        
        else if(player_t.position.bottom < screenHeight && (myMouse.y > player_t.position.bottom))
        {
            player_t.position.top -= (player_t.myPos.y -(10));
            player_t.position.bottom -= (player_t.myPos.y -(10));
        }
}