opengl - Animation with VCL Component (WM_PAINT) -

the problem opengl animation stops while mouse button clicked on tform component (border, caption ..). mouse button released animation goes on.

// drawing scene   void tmainform::drawglscene() {     glclearcolor(1,1,1,1);     glclear(gl_color_buffer_bit | gl_depth_buffer_bit);     drawfigure();     swapbuffers(hdc); }  // catching wm_paint  lresult callback newwindowprocpanel3d(hwnd hwnd, uint msg, wparam w, lparam l) {     switch (msg)     {         case wm_erasebkgnd :         {             return 1;         }         case wm_paint :         {             mainform->drawglscene();         }         default: return callwindowproc((farproc)mainform->oldwindowprocpanel3d,             hwnd, msg, w, l);     }     return 0; }  // creating oldwindowprocpanel3d -  void __fastcall tmainform::formcreate(tobject *sender) {     oldwindowprocpanel3d = (wndproc)setwindowlong(panel3d->handle,         gwl_wndproc, (long)newwindowprocpanel3d); }  // --------- *.h : class tmainform : public tform {     private:        hdc hdc;     public:         wndproc oldwindowprocpanel3d; }  // generation event wm_paint   void tmainform::updatescene() {     invalidaterect(panel3d->handle, null, false); }  // animation code ( turn on 'animation' if radiobutton chosen)   void __fastcall tmainform::radiogroupclick(tobject *sender) {     if (radiogroup->itemindex == 0)        animation = false;     else if (radiogroup->itemindex == 1)         animation = true;      if (animation)     {         while (animation)        {             application->processmessages();             updatescene();         }     } } 

what done not stop animation while changing sizes of form, usefull links?

that because main message loop blocked , secondary message loop running while window being dragged/resized. same thing happens when menus active, modal dialogs shown, etc. there nothing can that, how windows operates.

btw, assuming panel3d atpanelor similar vcl control, should subclass itswindowprocproperty instead ofsetwindowslong(), since thetwincontrol::handle` property not persistent.

and need rid of use of application->processmessages() altogether. never call directly unless absolutely necessary.

try instead:

class tmainform : public tform { private:     hdc hdc;     bool animation;     twndmethod oldwindowprocpanel3d;     void drawglscene();     void __fastcall newwindowprocpanel3d(tmessage &message); public:     __fastcall tmainform(tcomponent *owner); }; 

// creating oldwindowprocpanel3d - __fastcall tmainform::tmainform(tcomponent *owner)     : tform(owner) {     oldwindowprocpanel3d = panel3d->windowproc;     panel3d->windowproc = &newwindowprocpanel3d; }  // drawing scene  void tmainform::drawglscene() {     glclearcolor(1,1,1,1);     glclear(gl_color_buffer_bit | gl_depth_buffer_bit);     drawfigure();     swapbuffers(hdc); }  // catching wm_paint  void __fastcall tmainform::newwindowprocpanel3d(tmessage &message) {     switch (message.msg)     {         case wm_erasebkgnd :         {             message.result = 1;             break;         }          case wm_paint :         {             drawglscene();             if (animation)                 updatescene();             break;         }          default:         {             oldwindowprocpanel3d(message);             break;         }     } }  // generation event wm_paint  void tmainform::updatescene() {     panel3d->invalidate(); }  // animation code ( turn on 'animation' if radiobutton chosen)  void __fastcall tmainform::radiogroupclick(tobject *sender) {     if (radiogroup->itemindex == 0)         animation = false;     else if (radiogroup->itemindex == 1)         animation = true;      if (animation)         updatescene(); }