#include <windows.h>
#include <math.h>
#define febr    800    // BREITE 
#define feho    600    // HOEHE 
//---------------------VARIABLEN-------------------------------------
int 
bx, by,     // BILD X Y 
s,          // SCHALTER 
rf, gf, bf; // FARBEN 
double 
px, py,     // POSITION        X Y 
vx, vy,     // GESCHWINDIGKEIT X Y 
ax, ay,     // BESCHLEUNIGUNG  X Y 
r,          // ABSTAND 
g,          // GRAVITATION 
hx, hy,     // HILFS   X Y 
zx, zy,     // ZEICHEN X Y 
a,          // WINKEL 
z,          // ZAEHLER 
er,         // R  ERDE 
sr,         // R  SYNCHRON 
gm;         // GM ERDE 
//-------------------------------------------------------------------
static int  cxClient, cyClient ;
HDC hdc ;

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
     static TCHAR szAppName[] = TEXT ("DASSISSESS") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;
     
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;

     if (!RegisterClass (&wndclass))
     {
          MessageBox (NULL, TEXT ("Program requires Windows NT!"), 
                      szAppName, MB_ICONERROR) ;
          return 0 ;
     }
     
     hwnd = CreateWindow (szAppName, TEXT ("DASSISSESS"),
                          WS_OVERLAPPEDWINDOW, 0, 0, febr, feho, 
                          NULL, NULL, hInstance, NULL) ;

     ShowWindow (hwnd, SW_SHOWMAXIMIZED) ;
     UpdateWindow (hwnd) ;
     
     while (GetMessage (&msg, NULL, 0, 0))
     {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     return msg.wParam ;
}
//------------------------------------UNTERPROGRAMME-----------------
void bahn(void){      // UMLAUFBAHN 
s  = 0;               // SCHALTER 
hupf:                 // WIEDERHOLEN 
a = z * 8 * atan( 1 ) / 86164.0905;   // STERNSEKUNDEN 
hx = px; hy = py;                     // HILFS X Y 
zx = hx * cos( a ) - hy * sin( a );   // DREHEN 
zy = hx * sin( a ) + hy * cos( a ); 
z  =  z + 1 ;                         // ZAEHLER 
bx = (int)floor(0.5+125+px*0.000015); // BILD ZEICHNEN 
by = (int)floor(0.5+250+py*0.000015); 
if(bx<  0){goto nein;}                // AUSSERHALB 
if(bx>799){goto nein;} 
if(by<  0){goto nein;} 
if(by>599){goto nein;} 
SetPixel( hdc, bx, by, RGB( rf, gf, bf ) ); 
nein: ; 
bx = (int)floor(0.5+125+zx*0.000015); // BILD GEDREHT 
by = (int)floor(0.5+250+zy*0.000015); 
if(bx<  0){goto neyn;}                // AUSSERHALB 
if(bx>799){goto neyn;} 
if(by<  0){goto neyn;} 
if(by>599){goto neyn;} 
SetPixel( hdc, bx, by, RGB( rf, gf, bf ) ); 
neyn: ; 
r = sqrt(px*px+py*py);    // ABSTAND 
g = -gm/(r*r);            // GRAVITATION 
ax = g*px/r; ay = g*py/r; // KOMPONENTEN     X Y 
vx = vx+ax; vy = vy+ay;   // GESCHWINDIGKEIT X Y 
px = px+vx; py = py+vy;   // POSITION        X Y 
if(r<  (er-5000)){goto ausi;}  // KOLLISION 
if(r>10000000000){goto ausi;}  // FLUCHT 
if(py>  0){s=1;}               // UNTERE HAELFTE 
if(s <  1){goto hupf;}         // OBERE  HAELFTE 
if(py>  0){goto hupf;}         // UNTERE HAELFTE 
ausi: ; 
} 
//-------------------------------------------------------------------
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	 PAINTSTRUCT ps ;
    
     switch (message)
     {
     case WM_SIZE:
          cxClient = LOWORD (lParam) ;
          cyClient = HIWORD (lParam) ;
          return 0 ;
          
     case WM_PAINT:
          hdc = BeginPaint (hwnd, &ps) ;
//----------------------------------------HAUPTPROGRAMM--------------
gm = 3.986004418e14;    // GM ERDE 
er =  6378160;          // R  ERDE 
sr = 42164172;          // R  SYNCHRON 
rf =   0; gf = 127; bf = 255; z =   0;        // BLAU        ERDE 
px = er ; py =   0; vx =   0; vy = -sqrt(gm/er);          bahn(); 
rf =   0; gf = 255; bf =   0; z =   0;        // GRUEN   SYNCHRON 
px = sr ; py =   0; vx =   0; vy = -sqrt(gm/sr);          bahn(); 
rf = 255; gf =   0; bf = 255; z =   0;        // VIOLETT    STURZ 
px = sr ; py =   0; vx =   0; vy =  0;                    bahn(); 
rf = 127; gf = 127; bf =   0; z =   0;        // GELB     HOHMANN 
px = sr ; py =   0; vx =   0; vy = -sqrt(gm/sr) * 0.5124; bahn(); 
rf =   0; gf =   0; bf =   0; z =   0;        // SCHWARZ  GEOFALL 
px = sr ; py =   0; vx =   0; vy = -sqrt(gm/sr) * 0.31;   bahn(); 
//-------------------------------------------------------------------
		  EndPaint (hwnd, &ps) ;
          return 0 ;
          
     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}