2D游戏编程5—锁定频率
核心利用win心跳函数GetTickCount利用差量锁定fps，如下代码锁定30fps，缺点为如果计算机不能以30fps运行，程序将低于30fps
#define WIN32_LEAN_AND_MEAN // just say no to MFC #include <windows.h> // include all the windows headers #include <windowsx.h> // include useful macros #include <mmsystem.h> // very important and include WINMM.LIB too! #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 300 // MACROS ///////////////////////////////////////////////// #define KEYDOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) #define KEYUP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1) // GLOBALS //////////////////////////////////////////////// HWND main_window_handle = NULL; // globally track main window HINSTANCE hinstance_app = NULL; // globally track hinstance char buffer[80]; // general printing buffer // 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 char buffer[80]; // used to print strings // what is the message switch(msg) { case WM_CREATE: { // do initialization stuff here // return success return(0); } break; case WM_PAINT: { // simply validate the window hdc = BeginPaint(hwnd,&ps); // end painting EndPaint(hwnd,&ps); // return success return(0); } break; case WM_DESTROY: { // kill the application, this sends a WM_QUIT message PostQuitMessage(0); // return success 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) { WNDCLASSEX winclass; // this will hold the class we create HWND hwnd; // generic window handle MSG msg; // generic message HDC hdc; // graphics device context HPEN pen=NULL; // used to draw screen saver int color_change_count = 100; // used to track when to change color // first fill in the window class stucture winclass.cbSize = sizeof(WNDCLASSEX); 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; winclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION); // save hinstance in global hinstance_app = hinstance; // register the window class if (!RegisterClassEx(&winclass)) return(0); // create the window if (!(hwnd = CreateWindowEx(NULL, // extended style WINDOW_CLASS_NAME, // class "Time Inverval Locked Screen Saver", // title WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0,0, // initial x,y WINDOW_WIDTH, // initial width WINDOW_HEIGHT,// initial height NULL, // handle to parent NULL, // handle to menu hinstance,// instance of this application NULL))) // extra creation parms return(0); // save main window handle main_window_handle = hwnd; // get the dc and hold onto it hdc = GetDC(hwnd); // seed random number generator srand(GetTickCount()); // endpoints of line int x1 = rand()%WINDOW_WIDTH; int y1 = rand()%WINDOW_HEIGHT; int x2 = rand()%WINDOW_WIDTH; int y2 = rand()%WINDOW_HEIGHT; // intial velocity of each end int x1v = -4 + rand()%8; int y1v = -4 + rand()%8; int x2v = -4 + rand()%8; int y2v = -4 + rand()%8; // enter main event loop, but this time we use PeekMessage() // instead of GetMessage() to retrieve messages while(TRUE) { // get time referrence DWORD start_time = GetTickCount(); // test if there is a message in queue, if so get it 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 // is it time to change color if (++color_change_count >= 100) { // reset counter color_change_count = 0; // create a random colored pen if (pen) DeleteObject(pen); // create a new pen pen = CreatePen(PS_SOLID,1,RGB(rand()%256,rand()%256,rand()%256)); // select the pen into context SelectObject(hdc,pen); } // end if // move endpoints of line x1+=x1v; y1+=y1v; x2+=x2v; y2+=y2v; // test if either end hit window edge if (x1 < 0 || x1 >= WINDOW_WIDTH) { // invert velocity x1v=-x1v; // bum endpoint back x1+=x1v; } // end if if (y1 < 0 || y1 >= WINDOW_HEIGHT) { // invert velocity y1v=-y1v; // bum endpoint back y1+=y1v; } // end if // now test second endpoint if (x2 < 0 || x2 >= WINDOW_WIDTH) { // invert velocity x2v=-x2v; // bum endpoint back x2+=x2v; } // end if if (y2 < 0 || y2 >= WINDOW_HEIGHT) { // invert velocity y2v=-y2v; // bum endpoint back y2+=y2v; } // end if // move to end one of line MoveToEx(hdc, x1,y1, NULL); // draw the line to other end LineTo(hdc,x2,y2); // lock time to 30 fps which is approx. 33 milliseconds while((GetTickCount() - start_time) < 33); // main game processing goes here if (KEYDOWN(VK_ESCAPE)) SendMessage(hwnd, WM_CLOSE, 0,0); } // end while // release the device context ReleaseDC(hwnd,hdc); // return to Windows like this return(msg.wParam); } // end WinMain ///////////////////////////////////////////////////////////
