Windows Game Programming for Dummies (2nd Edition)/WinGamProgFD.iso/pc/Source/GPCHAP05/PROG5_7.CPP

C/C++ Source or Header | 2002-04-25 | 5.4 KB | 211 lines

// PROG5_7.CPP - a bouncing ball demo of ellipse()

// INCLUDES ///////////////////////////////////////////////
#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <windowsx.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// DEFINES ////////////////////////////////////////////////

// defines for windows
#define WINDOW_CLASS_NAME "WINCLASS1"
#define WINDOW_WIDTH  400
#define WINDOW_HEIGHT 400

// general defines
#define BALL_RADIUS 20

// GLOBALS ////////////////////////////////////////////////
HWND main_window_handle = NULL; // save the window handle
HPEN blue_pen, black_pen;       // pens to draw with

// FUNCTIONS //////////////////////////////////////////////
LRESULT CALLBACK WindowProc(HWND hwnd,
                            UINT msg,
                            WPARAM wparam,
                            LPARAM lparam)
{
// this is the main message handler of the system
PAINTSTRUCT        ps;        // used in WM_PAINT
HDC                hdc;    // handle to a device context

// what is the message
switch(msg)
    {
    case WM_CREATE:
        {
        // do initialization stuff here
        // create the pens here
        blue_pen  = CreatePen(PS_SOLID,0, RGB(0,0,255));
        black_pen = CreatePen(PS_SOLID,0, RGB(0,0,0));
        return(0);
        } break;

    case WM_PAINT:
        {
        // simply validate the window
        hdc = BeginPaint(hwnd,&ps);
           EndPaint(hwnd,&ps);
        return(0);
           } break;

    case WM_DESTROY:
        {
        // kill the application

        // delete the pens
        DeleteObject(blue_pen);
        DeleteObject(black_pen);

        PostQuitMessage(0);
        return(0);
        } break;

    default:break;

    } // end switch

// process any messages that we didn't take care of
return (DefWindowProc(hwnd, msg, wparam, lparam));

} // end WinProc

// WINMAIN ////////////////////////////////////////////////
int WINAPI WinMain(    HINSTANCE hinstance,
                    HINSTANCE hprevinstance,
                    LPSTR lpcmdline,
                    int ncmdshow)
{

WNDCLASS winclass;    // this will hold the class we create
HWND     hwnd;        // generic window handle
MSG         msg;        // generic message
HDC      hdc;       // generic dc
PAINTSTRUCT ps;     // generic paintstruct
RECT     rect;      // generic rectangle
HBRUSH   hbrush;    // generic brush handle

int ball_x = WINDOW_WIDTH/2, // initial position of ball
    ball_y = WINDOW_WIDTH/2;

int dx = 4, // initial velocity of ball
    dy = 2;

// first fill in the window class stucture
winclass.style            = CS_DBLCLKS | CS_OWNDC |
                          CS_HREDRAW | CS_VREDRAW;
winclass.lpfnWndProc    = WindowProc;
winclass.cbClsExtra        = 0;
winclass.cbWndExtra        = 0;
winclass.hInstance        = hinstance;
winclass.hIcon            = LoadIcon(NULL, IDI_APPLICATION);
winclass.hCursor        = LoadCursor(NULL, IDC_ARROW);
winclass.hbrBackground    = (HBRUSH)GetStockObject(BLACK_BRUSH);
winclass.lpszMenuName    = NULL;
winclass.lpszClassName    = WINDOW_CLASS_NAME;

// register the window class
if (!RegisterClass(&winclass))
    return(0);

// create the window
if (!(hwnd = CreateWindow(WINDOW_CLASS_NAME, // class
                          "Bouncing Ball Screen Saver",     // title
                          WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                           0,0,       // x,y
                          WINDOW_WIDTH,  // width
                          WINDOW_HEIGHT, // height
                          NULL,       // handle to parent
                          NULL,       // handle to menu
                          hinstance,// instance
                          NULL)))    // creation parms
return(0);

// save the window handle in a global
main_window_handle = hwnd;

// enter main event loop
while(1)
    {
    if (PeekMessage(&msg,NULL,0,0,PM_REMOVE))
        {
        // test if this is a quit
        if (msg.message == WM_QUIT)
           break;

        // translate any accelerator keys
        TranslateMessage(&msg);

        // send the message to the window proc
        DispatchMessage(&msg);
        } // end if

    // main game processing goes here /////////////////////

    // get the graphics device context
    hdc = GetDC(hwnd);

    // fill in rect structure
    rect.left  = ball_x - BALL_RADIUS;
    rect.right = ball_x + BALL_RADIUS;
    rect.top   = ball_y - BALL_RADIUS;
    rect.bottom= ball_y + BALL_RADIUS;

    // erase the ball /////////////////////////////////////
    SelectObject(hdc, GetStockObject(BLACK_BRUSH));
    SelectObject(hdc, black_pen);
    Ellipse(hdc, rect.left, rect.top, rect.right, rect.bottom);

    // move the ball //////////////////////////////////////
    ball_x+=dx;
    ball_y+=dy;

    // test for collision with wall, if so reverse direction
    if (ball_x >= WINDOW_WIDTH || ball_x <=0)
       {
       // reverse x velocity
       dx=-dx;

       // move ball back
       ball_x+=dx;
       } // end if

    if (ball_y >= WINDOW_HEIGHT || ball_y <=0)
       {
       // reverse y velocity
       dy=-dy;

       // move ball back
       ball_y+=dy;
       } // end if

        // fill in rect structure with new position
    rect.left  = ball_x - BALL_RADIUS;
    rect.right = ball_x + BALL_RADIUS;
    rect.top   = ball_y - BALL_RADIUS;
    rect.bottom= ball_y + BALL_RADIUS;

    // draw the ball
    SelectObject(hdc, blue_pen);
    Ellipse(hdc, rect.left, rect.top, rect.right, rect.bottom);

    // release the device context
    ReleaseDC(hwnd,hdc);

    // slow things down a bit
    Sleep(10);

    } // end while

// return to Windows like this
return(msg.wParam);

} // end WinMain

///////////////////////////////////////////////////////////