// bouncingBall.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); // do nothing

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));

}

// ***************** 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",WS_OVERLAPPEDWINDOW |

WS_VISIBLE, 0,0, WINDOW_WIDTH, WINDOW_HEIGHT,

NULL,NULL, hinstance, NULL)))

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 bounding 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)

{ dx=-dx; // reverse x velocity

ball_x+=dx; // move ball back

}

if (ball_y >= WINDOW_HEIGHT || ball_y <=0)

{ dy=-dy; // reverse y velocity

ball_y+=dy; // move ball back

}

// 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);

SelectObject(hdc, GetStockObject(GRAY_BRUSH));

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