Win32 SDK

[M R Sriram]

Win 32 SDK

I am trying to write a small Bricks Program.

Here the bouncing ball is in a seperate thread while the primary

thread handles the paddle movements.

The basic BallProc is somewhat like this

DWORD WINAPI BallProc(LPVOID lpThreadParam)

{

HWND hwnd = (HWND)lpThreadParam;

RECT ClientRect;

POINT PrevBallPos;

HDC hdc;

hdc = GetDC(hwnd);

GetClientRect(hwnd,&ClientRect);

BallPos.x = ClientRect.right / 2;

BallPos.y = ClientRect.bottom / 2;

BallDir.x = 1;

BallDir.y = 1;

while(!ExitBallThread)

{

BitBlt(hdc,BallPos.x,BallPos.y,BallSize,BallSize,MemBallDC,0,0,SRCCOPY);

memcpy(&PrevBallPos,&BallPos,sizeof(POINT));

BallPos.x += BallDir.x;

BallPos.y += BallDir.y;

if(BallPos.y >= ClientRect.bottom - BallSize|| BallPos.y <= ClientRect.top)

BallDir.y = -BallDir.y;

if(BallPos.x >= ClientRect.right - BallSize|| BallPos.x <= ClientRect.left)

BallDir.x = -BallDir.x;

/* Problem here */

// Sleep(1);

PatBlt(hdc,PrevBallPos.x,PrevBallPos.y,BallSize,BallSize,WHITENESS);

}

ReleaseDC(hwnd,hdc);

ExitThread(0);

}

In the above code,if i do not give the Sleep,the ball movement is extremely

fast.However if i give Sleep(1) the ball slows down a lot it is very easy to

paddle it.I want to control the movement of the ball(ie i want the ball to move much faster than what i get with

Sleep(1) but not as fast as the one without Sleep(1)).


If anyone has got any ideas pl help me.


SriramMR

[Mats Bejedahl]

One simple solution would be to determine haw many pixel per second you want to move the ball.

The values in nPixelsPerSecond and nFramesPerSecond should not

be hardcoded since they should be changed depending on which speed the user wants and the performance of the PC it´s

running on.

int nPixelsPerSecond = 800; // High value = fast ball

int nFramesPerSecond = 100; // High value = smother graphichs

int nPixelsPerFrame = nPixelsPerSecond / nFramesPerSecond;

int nMilliSecondsBetweenFrames = 1000/*one second in ms*/ / nFramesPerSecond;

int nMilliSecondsElapsed;

GetClientRect(hwnd,&ClientRect);

BallPos.x = ClientRect.right / 2;

BallPos.y = ClientRect.bottom / 2;

BallDir.x = 2;

BallDir.y = 2;

while(::IsWindow(hwnd))

{

nMilliSecondsElapsed = (int)GetTickCount();

PatBlt(hdc,PrevBallPos.x,PrevBallPos.y,BallSize,BallSize,WHITENESS);

BitBlt(hdc,BallPos.x,BallPos.y,BallSize,BallSize,MemBallDC,0,0,SRCCOPY);

memcpy(&PrevBallPos,&BallPos,sizeof(POINT));

for ( int nIndex = 0; nIndex < nPixelsPerFrame; nIndex++ )

{

BallPos.x += BallDir.x;

BallPos.y += BallDir.y;

if(BallPos.y >= ClientRect.bottom - BallSize|| BallPos.y <= ClientRect.top)

BallDir.y = -BallDir.y;

if(BallPos.x >= ClientRect.right - BallSize|| BallPos.x <= ClientRect.left)

BallDir.x = -BallDir.x;

}

nMilliSecondsElapsed = (int)GetTickCount() - nMilliSecondsElapsed;

/* Problem here */

if ( nMilliSecondsElapsed < nMilliSecondsBetweenFrames )

{

Sleep(nMilliSecondsBetweenFrames - nMilliSecondsElapsed);

}



}

ReleaseDC(hwnd,hdc);

ExitThread(0);


Hope this is of some help to you

Mats Bejedahl