c++ - Non instantaneous/jerky movement using SDL2 & OpenGL -

i've been working on little 3d engine trying fix camera , make less jerky. i've been using sdl input , while works it's doing thing if press , hold button instantly move once pause , start moving making movement feel unresponsive.

i recorded gif of , while may hard see what's happening it'll give idea:

moving forward , right like:

w wwwwwwwwwwwwwwww aaaaaaaaaaaaaaaaaaaaa

the important code here feel free ask more if necessary:

//poll events     sdl_event event;     while (m_enginestate != enginestate::exit)     {         m_last = m_current;         m_current = sdl_getperformancecounter();         deltatime = (double)((m_current - m_last) * 1000 / sdl_getperformancefrequency());          while (sdl_pollevent(&event))         {             switch (event.type) {             case sdl_quit:                 m_enginestate = enginestate::exit;                 break;              case sdl_mousemotion:                 break;              case sdl_keydown:                 m_keys[event.key.keysym.sym] = true;                 break;             case sdl_keyup:                 m_keys[event.key.keysym.sym] = false;                 break;             }             processevents();         }  void engine::processevents() {     if (m_keys[sdlk_w])     {         m_camera->moveforward(5.0f*(deltatime*0.001));     }     if (m_keys[sdlk_s])     {         m_camera->moveforward(-5.0f*(deltatime*0.001));     }     if (m_keys[sdlk_d])     {         m_camera->moveright(5.0f*(deltatime*0.001));     }     if (m_keys[sdlk_a])     {         m_camera->moveright(-5.0f*(deltatime*0.001));     } }  void camera::moveforward(float amount) {       m_pos += m_forward * amount; }  void camera::moveright(float amount) {     m_pos += glm::cross(m_forward, m_up) * amount; } 

do not use sdl_pollevent sdl_keydown , sdl_keyup events, subject os keyboard repeat rates. great typing, not camera/player controls. use sdl_getkeyboardstate(null) in stead query current state of keys.

for example:

uint8* keystate = sdl_getkeystate(null);  if(keystate[sdl_scancode_w]) {   m_camera->moveforward(5.0f*(deltatime*0.001)); } if(keystate[sdl_scancode_s]) {   m_camera->moveforward(-5.0f*(deltatime*0.001)); } // etc 

(answer edited take corrections comments account)