Original Post
Hello, i was doing gravity simulation, and this is bascicly simulation of solar system, and the red object is the sun and the green one is the Haleys comet...problem is that the comet doesn;t follow it;s path and flies of when it gets close to the sun....does anyone know what is wrong with my gravity related calculations i am 90 % sure my mass and speed data is correct. MAIN: /* Changes in the program: Version 1: Creating the window done. Ploting a point on given (x,y) coordinats done. Animating a point to move by Vx*Dt Version 2: Added acceleration support. Forces have been added in order to find out the acceleration Class structure implemented. Point is not discribed using a structure. Version 3: Expension to animate in 2 dimension under the influence of 2 forces, in x, and y directions. Support for an array of points added. Gravitation forces are used to calculate the movemnet of the program An example system of 2 objects is models to show for both x and y forces. Version 4: Modeled earth-sun system. */ //Needed to create the windwo. #include #include #include #include #include #include //Class responsible for all physical calculataions, as well as drawing the point. #include "draw.h" using namespace std; //Limit the lines static const WORD MAX_CONSOLE_LINES = 1000; //This will redirected the output to a console. void RedirectIOToConsole(); //Window proc that will handle the paint and the quit messages. LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg, WPARAM wParam, LPARAM lParam); //Timer procedure is used to make sure that the drawing is done a given number of times a second //The time for each redraw is constant here. There are 33.3 frames per second drawn void CALLBACK TimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime); //Global object defintion of the method to do the drawing. CDraw o_draw; //Main program function, we start here int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,LPSTR lpCmdLine, int nCmdShow){ //Declare a window class information structure. used to register the windows WNDCLASSEX wcWndCls; //message structure, used to in relaying the messages sent to the window MSG mMsg; //Initializing the window class structure. wcWndCls.cbSize = sizeof(wcWndCls); wcWndCls.style = CS_OWNDC | CS_VREDRAW | CS_HREDRAW; wcWndCls.lpfnWndProc = WndProc; wcWndCls.cbClsExtra = 0; wcWndCls.cbWndExtra = 0; wcWndCls.hInstance = hInstance; wcWndCls.hIcon = LoadIcon(NULL, IDI_APPLICATION); wcWndCls.hCursor = LoadCursor(NULL, IDC_ARROW); wcWndCls.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH); wcWndCls.lpszMenuName = NULL; wcWndCls.lpszClassName = schAppName; wcWndCls.hIconSm = LoadIcon(hInstance, IDI_APPLICATION); //We register the window for use in subsequent class with createWindowEx RegisterClassEx(&wcWndCls); //Create the actual window.Name is declared in CreateWindowEx(WS_EX_OVERLAPPEDWINDOW,schAppName,schAppName,WS_OVERLAPPEDWINDOW | WS_VISIBLE,CW_USEDEFAULT, CW_USEDEFAULT, 640, 480, NULL, NULL, hInstance, NULL); //Create the timer to draw the window 33 times a second. SetTimer(NULL,0,0,(TIMERPROC)TimerProc); RedirectIOToConsole(); system("pause"); //Message loop while(GetMessage(&mMsg, NULL, 0, 0)){ TranslateMessage(&mMsg); DispatchMessage( &mMsg); } //Ending the program return static_cast(mMsg.wParam); } //Here we will process the messages sent LRESULT CALLBACK WndProc(HWND hWnd, UINT Msg,WPARAM wParam, LPARAM lParam){ switch(Msg){ //Draw the window now case WM_PAINT: o_draw.Draw(); break; //time to shut down case WM_DESTROY: PostQuitMessage(WM_QUIT); break; //pass the rest of the messages to the default procedure. default: return DefWindowProc(hWnd, Msg, wParam, lParam); } return 0; } //This function is a callback functions, and it will be called evry 30 milliseconds. //At that time it will make sure that the window is redrawn void CALLBACK TimerProc(HWND hwnd,UINT uMsg,UINT_PTR idEvent,DWORD dwTime){ //Update the windwo //Do NOT erase the background. //Set last parameter to true to do jsut that. InvalidateRect(FindWindow(0,schAppName),NULL,false); } //We redirect all the output to console we can debug the program normally. void RedirectIOToConsole(){ int hConHandle; long lStdHandle; CONSOLE_SCREEN_BUFFER_INFO coninfo; FILE *fp; AllocConsole(); GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE),&coninfo); coninfo.dwSize.Y = MAX_CONSOLE_LINES; SetConsoleScreenBufferSize(GetStdHandle(STD_OUTPUT_HANDLE),coninfo.dwSize); lStdHandle = (long)GetStdHandle(STD_OUTPUT_HANDLE); hConHandle = _open_osfhandle(lStdHandle, _O_TEXT); fp = _fdopen( hConHandle, "w" ); *stdout = *fp; setvbuf( stdout, NULL, _IONBF, 0 ); lStdHandle = (long)GetStdHandle(STD_INPUT_HANDLE); hConHandle = _open_osfhandle(lStdHandle, _O_TEXT); fp = _fdopen( hConHandle, "r" ); *stdin = *fp; setvbuf( stdin, NULL, _IONBF, 0 ); lStdHandle = (long)GetStdHandle(STD_ERROR_HANDLE); hConHandle = _open_osfhandle(lStdHandle, _O_TEXT); fp = _fdopen( hConHandle, "w" ); *stderr = *fp; setvbuf( stderr, NULL, _IONBF, 0 ); ios::sync_with_stdio(); } DRAW.H #ifndef DRAW_H_ #define DRAW_H_ //Regular header for all the windows stuff #include #include #include #include #include #include //to get rid of the std:: b4 the cout's. using namespace std; //Name of the application, inconsequential, used just for the class name of the window and the titel. static char schAppName[] = "Solar System Simulataion"; //Conversion to DIB color. #define COLOR(r, g ,b) ((DWORD) (((BYTE) (r) | ((WORD) (g) << 8)) |(((DWORD) (BYTE) (b)) << 16))) //structure that will be responsible for a single point. typedef struct gPOINT { double dPosX; double dPosY; double dVeloX; double dVeloY; double dMass; double dForceX; double dForceY; double dAccelX; double dAccelY; }; //Class to draw the point. class CDraw{ private: //array of 10 points(Solar System will be stored here) //For now only a few of them are used to make gPOINT point[11]; //Device context. Used to set pixesls HDC hDC; //Paint structure, used in Being/EndPaint functions. PAINTSTRUCT Ps; private: double Time(long double dTimeMs); double Velocity(double dLastVelocity,double dAcceleration,double DTime); double Acceleration(double dForce,double dMass); double ForceX(gPOINT point,gPOINT point2); double ForceY(gPOINT point,gPOINT point2); double Gravity(gPOINT point,gPOINT point2); double Pytheg(gPOINT point,gPOINT point2); int PositionX(double x); int PositionY(double y); void Point(gPOINT point,DWORD dwColor); public: CDraw(); ~CDraw(); void Draw(); }; #endif DRAW.CPP #include "draw.h" #include "math.h" //Scaling of the distance const double DistanceFactor=5.25e10; //Scaling of the time const double TimeFactor=1000000; bool first=true; double iTime=0; //Initialize 2 points givng them some values. CDraw::CDraw(){ ZeroMemory(point,sizeof(gPOINT)*11); //Set Sun's mass point[0].dMass=1.99e30; //Set comet's position in relation to earth. point[1].dPosX=5.25e12; //point[1].dPosX=2.67e12; point[1].dPosY=0; //Set the initial velocity for the comet. point[1].dVeloY=-896; point[1].dVeloX=0; //Set the mass of the conet. point[1].dMass=5.2e11; } //Deinitialize the points, giving them 0's CDraw::~CDraw(){ ZeroMemory(point,sizeof(gPOINT)*11); } //Do the drawing. //Time scal;ing is not done corrrectly, this is just a test void CDraw::Draw(){ hDC = BeginPaint(FindWindow(0,schAppName), &Ps); if(first)Point(point[1],COLOR(0,0,255)); point[1].dForceX=ForceX(point[1],point[0]); point[1].dForceY=ForceY(point[1],point[0]); cout<<"Force on the moon in x:"<=364){ cout<<"Time passed(d):"<<iTime/86400<<" "<<point[1].dPosX<<endl; Point(point[1],COLOR(0,0,255)); }*/ system("pause"); EndPaint(FindWindow(0,schAppName), &Ps ); } //Do the time scaling using Time factor double CDraw::Time(long double dTimeMs){ return (dTimeMs*TimeFactor); } //calculate the new velocity. newVelocity=oldVelocioty +AccelerationTime double CDraw::Velocity(double dLastVelocity,double dAcceleration,double dTime){ if(first){ first=false; return dLastVelocity+dAcceleration*0.5*dTime; } return dLastVelocity+dAcceleration*dTime; } //Do acceleration from f=ma double CDraw::Acceleration(double dForce,double dMass){ double a=dForce/dMass; return a; } //Calculate force in the X direction //Fx=forceGravity*changeinX/radius double CDraw::ForceX(gPOINT point,gPOINT point2){ double dForce=(Gravity(point,point2)*(-point.dPosX)/Pytheg(point,point2)); return dForce; } //Calculate force in the X direction //Fy=forceGravity*changeiny/radius double CDraw::ForceY(gPOINT point,gPOINT point2){ double dForce=(Gravity(point,point2)*(-point.dPosY)/Pytheg(point,point2)); return dForce; } //Gravity, Fg=Gmm/r^2 double CDraw::Gravity(gPOINT point,gPOINT point2){ return ((6.67e-11*point.dMass*point2.dMass)/pow(Pytheg(point,point2),2)); } //r^2=a^2+b^2 //r=sqrt(a^2+b^2) double CDraw::Pytheg(gPOINT point,gPOINT point2){ return sqrt(pow(point2.dPosX-point.dPosX,2)+pow(point2.dPosY-point.dPosY,2)); } //Convert to screen cords int CDraw::PositionX(double x){ double ret=((x/DistanceFactor)+320); // cout<<"x: "<<x<<"ret: "<<ret<<endl; return ret; } //Convert to screen coords int CDraw::PositionY(double y){ return ((y/DistanceFactor)+240); } //Do a 5 pixel method for a point. void CDraw::Point(gPOINT point,DWORD dwColor){ SetPixel(hDC,PositionX(point.dPosX), PositionY(point.dPosY),dwColor); SetPixel(hDC,PositionX(point.dPosX), PositionY(point.dPosY)-1,dwColor); SetPixel(hDC,PositionX(point.dPosX), PositionY(point.dPosY)+1,dwColor); SetPixel(hDC,PositionX(point.dPosX)+1,PositionY(point.dPosY),dwColor); SetPixel(hDC,PositionX(point.dPosX)-1,PositionY(point.dPosY),dwColor); } Thx
