vsync by DELTRON

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// GLOBALS int VSYNC_STATE; // tests vsync state change bool test_vsync(void) {     // get current vsync state     int    VSYNC_STATE = wglGetSwapIntervalEXT();     // attempt to change to another state     wglSwapIntervalEXT(!VSYNC_STATE);     int nvss = wglGetSwapIntervalEXT();     // return false if failed     if (VSYNC_STATE == nvss) return false;     // else, it's changeable.. restore state     wglSwapIntervalEXT(VSYNC_STATE);     return true; } // set vsync state (also records global state) bool set_vsync(int vs) {     VSYNC_STATE = wglGetSwapIntervalEXT();     if (VSYNC_STATE==vs) return true;     wglSwapIntervalEXT(vs);     int nvss = wglGetSwapIntervalEXT();     return (vs==nvss); } // restores previous state void restore_vsync(void) {     wglSwapIntervalEXT(VSYNC_STATE); }     // init extensions - must not be called before establishing an opengl rendering context void initextensions() {   const unsigned char * extensions_string = glGetString(GL_EXTENSIONS);   if (!extensions_string)   {       MessageBox(NULL,"Could not get supported OpenGL extension list.","ERROR",MB_ICONERROR);       exit(0);   }   if (strstr((const char *)extensions_string,"WGL_EXT_swap_control"))   {     wglSwapIntervalEXT = (PFNWGLEXTSWAPCONTROLPROC)wglGetProcAddress("wglSwapIntervalEXT");     wglGetSwapIntervalEXT = (PFNWGLEXTGETSWAPINTERVALPROC)wglGetProcAddress("wglGetSwapIntervalEXT");   }   else   {       MessageBox(NULL,"Did not find support for WGL_EXT_swap_control.","ERROR",MB_ICONERROR);       exit(0);   } }