c - The triangle is not displayed in OpenGL application -

i'm trying make first polygon.

because wrote code, complied , voila ... triangle not displayed :(

what wrong code?

#pragma once  #include <windows.h> #include <stdio.h> #include <stdlib.h> #include <gl\gl.h> #include <gl\glu.h> #include <gl\glut.h>  hdc         hdc=null; hglrc       hrc=null;  glvoid gl_resizeglscene(glsizei width, glsizei height); int gl_init( glvoid ); int gl_drawit( glvoid );  typedef struct {     hwnd hwnd; } glab_t;  static glab_t glab;  char szclassname[ ] = "glab";  static lresult callback windowprocedure (hwnd hwnd, uint message, wparam wparam, lparam lparam) {     switch (message) {         case wm_destroy:             postquitmessage (0);             break;         case wm_size:             gl_resizeglscene(loword(lparam),hiword(lparam));             break;         default:             return defwindowproc (hwnd, message, wparam, lparam);     }     return 0; }   int winapi winmain (hinstance hinstance, hinstance hprevinstance, lpstr lpcmdline, int ncmdshow) {     msg messages;     rect rect;     wndclassex wndclass;     int screenwidth, screenheight;     int x, y, w, h;     gluint      pixelformat;      screenwidth = getsystemmetrics(sm_cxscreen);     screenheight = getsystemmetrics(sm_cyscreen);      rect.left = (screenwidth - 582) / 2;     rect.top = (screenheight - 358) / 2;     rect.right = rect.left + 582;     rect.bottom = rect.top + 358;      x = rect.left;     y = rect.top;     w = 640;     h = 480;       wndclass.hinstance = hinstance;     wndclass.lpszclassname = szclassname;     wndclass.lpfnwndproc = windowprocedure;     wndclass.style = cs_dblclks;     wndclass.cbsize = sizeof (wndclassex);     wndclass.hicon = loadicon (null, idi_application);     wndclass.hiconsm = loadicon (null, idi_application);     wndclass.hcursor = loadcursor (null, idc_arrow);     wndclass.lpszmenuname = null;     wndclass.cbclsextra = 0;     wndclass.cbwndextra = 0;     wndclass.hbrbackground = (hbrush)(color_btnface + 1);      if (!registerclassex (&wndclass)) {         return 0;     }      glab.hwnd = createwindowex (            0,            szclassname,            "glab - opengl",            ws_overlappedwindow,            x,            y,            w,            h,            hwnd_desktop,            null,            hinstance,            null             );      static  pixelformatdescriptor pfd=  {         sizeof(pixelformatdescriptor),         1,         pfd_draw_to_window | pfd_support_opengl | pfd_doublebuffer,         pfd_type_rgba,         16, // can 32 tough :)         0, 0, 0, 0, 0, 0,         0,         0,         0,         0, 0, 0, 0,          16,          0,         0,         pfd_main_plane,          0,         0, 0, 0      };      if (!(hdc=getdc(glab.hwnd))) {         messagebox(null,"can't create gl device context.","error",mb_ok|mb_iconexclamation);         return false;     }      if (!(pixelformat=choosepixelformat(hdc,&pfd))) {         messagebox(null,"can't find suitable pixelformat.","error",mb_ok|mb_iconexclamation);         return false;     }      if(!setpixelformat(hdc,pixelformat,&pfd)) {         messagebox(null,"can't set pixelformat.","error",mb_ok|mb_iconexclamation);         return false;     }      if (!(hrc=wglcreatecontext(hdc))) {         messagebox(null,"can't create gl rendering context.","error",mb_ok|mb_iconexclamation);         return false;     }      if(!wglmakecurrent(hdc,hrc)) {         messagebox(null,"can't activate gl rendering context.","error",mb_ok|mb_iconexclamation);         return false;     }      showwindow (glab.hwnd, ncmdshow);     setforegroundwindow(glab.hwnd);     setfocus(glab.hwnd);     gl_resizeglscene( w, h );      if (!gl_init() ) {         messagebox(null,"initialization failed.","error",mb_ok|mb_iconexclamation);         return false;     }      if( !gl_drawit() ) {         messagebox(null,"initialization failed.","error",mb_ok|mb_iconexclamation);         return false;     }      while (getmessage (&messages, null, 0, 0)) {         translatemessage(&messages);         dispatchmessage(&messages);     }      return messages.wparam; }  glvoid gl_resizeglscene(glsizei width, glsizei height) {     if (height==0) {         height=1;     }      glviewport(0,0,width,height);     glmatrixmode(gl_projection);     glloadidentity();     gluperspective(45.0f,(glfloat)width/(glfloat)height,0.1f,100.0f);     glmatrixmode(gl_modelview);     glloadidentity(); }  int gl_init( glvoid ) {     glshademodel(gl_smooth);     glclearcolor(0.0f, 0.0f, 0.0f, 0.5f);     glcleardepth(1.0f);     glenable(gl_depth_test);     gldepthfunc(gl_lequal);     glhint(gl_perspective_correction_hint, gl_nicest);     return true; }  int gl_drawit( glvoid ) {     glclear(gl_color_buffer_bit | gl_depth_buffer_bit);     glloadidentity();     gltranslatef(-1.5f,0.0f,-6.0f);     glbegin(gl_triangles);         glvertex3f( 0.0f, 1.0f, 0.0f);         glvertex3f(-1.0f,-1.0f, 0.0f);         glvertex3f( 1.0f,-1.0f, 0.0f);     glend();                 return true; } 

using mc visual c++ 2010 express , opengl 1.4.

you need swapbuffers() call in there after render scene:

#include <windows.h> #include <gl/gl.h> #include <gl/glu.h>  hdc         hdc=null; hglrc       hrc=null;  glvoid gl_resizeglscene(glsizei width, glsizei height); int gl_init( glvoid ); int gl_drawit( glvoid );  typedef struct {     hwnd hwnd; } glab_t;  static glab_t glab;  char szclassname[ ] = "glab";  static lresult callback windowprocedure (hwnd hwnd, uint message, wparam wparam, lparam lparam) {     switch (message) {         case wm_destroy:             postquitmessage (0);             break;         case wm_size:             gl_resizeglscene(loword(lparam),hiword(lparam));             break;         default:             return defwindowproc (hwnd, message, wparam, lparam);     }     return 0; }   int winapi winmain (hinstance hinstance, hinstance hprevinstance, lpstr lpcmdline, int ncmdshow) {     msg messages;     rect rect;     wndclassex wndclass;     int screenwidth, screenheight;     int x, y, w, h;     gluint      pixelformat;      screenwidth = getsystemmetrics(sm_cxscreen);     screenheight = getsystemmetrics(sm_cyscreen);      rect.left = (screenwidth - 582) / 2;     rect.top = (screenheight - 358) / 2;     rect.right = rect.left + 582;     rect.bottom = rect.top + 358;      x = rect.left;     y = rect.top;     w = 640;     h = 480;       wndclass.hinstance = hinstance;     wndclass.lpszclassname = szclassname;     wndclass.lpfnwndproc = windowprocedure;     wndclass.style = cs_dblclks;     wndclass.cbsize = sizeof (wndclassex);     wndclass.hicon = loadicon (null, idi_application);     wndclass.hiconsm = loadicon (null, idi_application);     wndclass.hcursor = loadcursor (null, idc_arrow);     wndclass.lpszmenuname = null;     wndclass.cbclsextra = 0;     wndclass.cbwndextra = 0;     wndclass.hbrbackground = (hbrush)(color_btnface + 1);      if (!registerclassex (&wndclass)) {         return 0;     }      glab.hwnd = createwindowex (            0,            szclassname,            "glab - opengl",            ws_overlappedwindow,            x,            y,            w,            h,            hwnd_desktop,            null,            hinstance,            null             );      static  pixelformatdescriptor pfd=  {         sizeof(pixelformatdescriptor),         1,         pfd_draw_to_window | pfd_support_opengl | pfd_doublebuffer,         pfd_type_rgba,         16, // can 32 tough :)         0, 0, 0, 0, 0, 0,         0,         0,         0,         0, 0, 0, 0,          16,          0,         0,         pfd_main_plane,          0,         0, 0, 0      };      if (!(hdc=getdc(glab.hwnd))) {         messagebox(null,"can't create gl device context.","error",mb_ok|mb_iconexclamation);         return false;     }      if (!(pixelformat=choosepixelformat(hdc,&pfd))) {         messagebox(null,"can't find suitable pixelformat.","error",mb_ok|mb_iconexclamation);         return false;     }      if(!setpixelformat(hdc,pixelformat,&pfd)) {         messagebox(null,"can't set pixelformat.","error",mb_ok|mb_iconexclamation);         return false;     }      if (!(hrc=wglcreatecontext(hdc))) {         messagebox(null,"can't create gl rendering context.","error",mb_ok|mb_iconexclamation);         return false;     }      if(!wglmakecurrent(hdc,hrc)) {         messagebox(null,"can't activate gl rendering context.","error",mb_ok|mb_iconexclamation);         return false;     }      showwindow (glab.hwnd, ncmdshow);     setforegroundwindow(glab.hwnd);     setfocus(glab.hwnd);     gl_resizeglscene( w, h );      if (!gl_init() ) {         messagebox(null,"initialization failed.","error",mb_ok|mb_iconexclamation);         return false;     }      while (getmessage (&messages, null, 0, 0)) {         translatemessage(&messages);         dispatchmessage(&messages);          if( !gl_drawit() ) {             messagebox(null,"initialization failed.","error",mb_ok|mb_iconexclamation);             return false;         }         swapbuffers(hdc);     }      return messages.wparam; }  glvoid gl_resizeglscene(glsizei width, glsizei height) {     if (height==0) {         height=1;     }      glviewport(0,0,width,height);     glmatrixmode(gl_projection);     glloadidentity();     gluperspective(45.0f,(glfloat)width/(glfloat)height,0.1f,100.0f);     glmatrixmode(gl_modelview);     glloadidentity(); }  int gl_init( glvoid ) {     glshademodel(gl_smooth);     glclearcolor(0.0f, 0.0f, 0.0f, 0.5f);     glcleardepth(1.0f);     glenable(gl_depth_test);     gldepthfunc(gl_lequal);     glhint(gl_perspective_correction_hint, gl_nicest);     return true; }  int gl_drawit( glvoid ) {     glclear(gl_color_buffer_bit | gl_depth_buffer_bit);     glloadidentity();     gltranslatef(-1.5f,0.0f,-6.0f);     glbegin(gl_triangles);         glvertex3f( 0.0f, 1.0f, 0.0f);         glvertex3f(-1.0f,-1.0f, 0.0f);         glvertex3f( 1.0f,-1.0f, 0.0f);     glend();                 return true; } 

edit: moved gl_drawit() call event loop redraws in response resize events. well, event @ really.