粒子系统的实现

/**************************************************************************** snow.cpp This demo program demonstrates a simple snowstorm particle effect Author : Dave Astle Date : 3/17/2001 Written for OpenGL Game Programming *****************************************************************************/ /********************************* Includes *********************************/ #define WIN32_LEAN_AND_MEAN // get rid of Windows things we don't need #include <windows.h> // included in all Windows apps #include <winuser.h> // Windows constants #include <gl/gl.h> // OpenGL include #include <gl/glu.h> // OpenGL utilty library #include "snowstorm.h" #include "HiResTimer.h" #define WND_CLASS_NAME "OpenGL Window Class" /*************************** Constants and Macros ***************************/ const int SCREEN_WIDTH = 800; const int SCREEN_HEIGHT = 600; const int SCREEN_BPP = 32; const bool USE_FULLSCREEN = false; const char *APP_TITLE = "Snowstorm Demo"; /********************************* Globals **********************************/ HDC g_hdc; // device context HGLRC g_hrc; // rendering context BOOL g_isFullscreen = TRUE; // toggles fullscreen and windowed display BOOL g_isActive = TRUE; // false if window is minimized HWND g_hwnd = NULL; // main window handle HINSTANCE g_hInstance; // application instance CSnowstorm g_snowstorm(5000, vector3_t(0.0, 0.0, -5.0), 5.0, 5.0, 5.0); CHiResTimer g_timer; /******************************** Prototypes ********************************/ LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam); BOOL SetupWindow(const char *title, int width, int height, int bits, bool isFullscreen); BOOL KillWindow(); GLvoid ResizeScene(GLsizei width, GLsizei height); BOOL InitializeScene(); BOOL DisplayScene(float elapsedTime); BOOL Cleanup(); /***************************************************************************** WinMain() Windows entry point *****************************************************************************/ int WINAPI WinMain(HINSTANCE g_hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) { MSG msg; // message BOOL isDone; // flag indicatingen the app is done // if the window is set up correctly, we can proceed with the message loop if (SetupWindow(APP_TITLE, SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, USE_FULLSCREEN)) isDone = FALSE; // otherwise, we need to never enter the loop and proceed to exit else isDone = TRUE; g_timer.Init(); // main message loop while (!isDone) { if(PeekMessage(&msg, g_hwnd, NULL, NULL, PM_REMOVE)) { if (msg.message == WM_QUIT) // do we receive a WM_QUIT message? { isDone = TRUE; // if so, time to quit the application } else { TranslateMessage(&msg); // translate and dispatch to event queue DispatchMessage(&msg); } } // don't update the scene if the app is minimized if (g_isActive) { // update the scene every time through the loop DisplayScene(g_timer.GetElapsedSeconds()); // switch the front and back buffers to display the updated scene SwapBuffers(g_hdc); } } Cleanup(); KillWindow(); return msg.wParam; } // end WinMain() /***************************************************************************** WndProc() Windows message handler *****************************************************************************/ LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { switch(message) { case WM_ACTIVATE: // watch for the window being minimized and restored { if (!HIWORD(wParam)) { // program was restored or maximized g_isActive = TRUE; } else { // program was minimized g_isActive=FALSE; } return 0; } case WM_SYSCOMMAND: // look for screensavers and powersave mode { switch (wParam) { case SC_SCREENSAVE: // screensaver trying to start case SC_MONITORPOWER: // monitor going to powersave mode // returning 0 prevents either from happening return 0; default: break; } } break; case WM_CLOSE: // window is being closed { // send WM_QUIT to message queue PostQuitMessage(0); return 0; } case WM_SIZE: { // update perspective with new width and height ResizeScene(LOWORD(lParam), HIWORD(lParam)); return 0; } case WM_CHAR: { switch (toupper(wParam)) { case VK_ESCAPE: { // send WM_QUIT to message queue PostQuitMessage(0); return 0; } default: break; }; } break; case WM_MOVE: { // avoid a jump when the window is moved g_timer.GetElapsedSeconds(); break; } default: break; } return (DefWindowProc(hwnd, message, wParam, lParam)); } // end WndProc() /***************************************************************************** SetupWindow() Create the window and everything else we need, including the device and rendering context. If a fullscreen window has been requested but can't be created, the user will be prompted to attempt windowed mode. Finally, InitializeScene is called for application-specific setup. Returns TRUE if everything goes well, or FALSE if an unrecoverable error occurs. Note that if this is called twice within a program, KillWindow needs to be called before subsequent calls to SetupWindow. *****************************************************************************/ BOOL SetupWindow(const char *title, int width, int height, int bits, bool isFullscreen) { // set the global flag g_isFullscreen = isFullscreen; // get our instance handle g_hInstance = GetModuleHandle(NULL); WNDCLASSEX wc; // window class // fill out the window class structure wc.cbSize = sizeof(WNDCLASSEX); wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; wc.lpfnWndProc = WndProc; wc.cbClsExtra = 0; wc.cbWndExtra = 0; wc.hInstance = g_hInstance; wc.hIcon = LoadIcon(NULL, IDI_APPLICATION); // default icon wc.hIconSm = LoadIcon(NULL, IDI_WINLOGO); // windows logo small icon wc.hCursor = LoadCursor(NULL, IDC_ARROW); // default arrow wc.hbrBackground = NULL; // no background needed wc.lpszMenuName = NULL; // no menu wc.lpszClassName = WND_CLASS_NAME; // register the windows class if (!RegisterClassEx(&wc)) { MessageBox(NULL,"Unable to register the window class", "Error", MB_OK | MB_ICONEXCLAMATION); // exit and return FALSE return FALSE; } // if we're in fullscreen mode, set the display up for it if (g_isFullscreen) { // set up the device mode structure DEVMODE screenSettings; memset(&screenSettings,0,sizeof(screenSettings)); screenSettings.dmSize = sizeof(screenSettings); screenSettings.dmPelsWidth = width; // screen width screenSettings.dmPelsHeight = height; // screen height screenSettings.dmBitsPerPel = bits; // bits per pixel screenSettings.dmFields = DM_BITSPERPEL | DM_PELSWIDTH | DM_PELSHEIGHT; // attempt to switch to the resolution and bit depth we've selected if (ChangeDisplaySettings(&screenSettings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) { // if we can't get fullscreen, let them choose to quit or try windowed mode if (MessageBox(NULL, "Cannot run in the