I want to make a circle in Gtk GLArea. Which can be moved with the help of the mouse pointer. Here is a script, on which i want to draw the movable circles. Can anyone tell me how to do this?

//gcc $( pkg-config –cflags gtk4 ) -o bb glTriangle_gtk4.c $( pkg-config –libs gtk4 epoxy ) -lm

#include <epoxy/gl.h>
#include <epoxy/glx.h>
#include <gtk/gtk.h>

float xx, yy;

static void on_realize(GtkGLArea *area) {
  gtk_gl_area_make_current (area);
  if (gtk_gl_area_get_error (area) != NULL)
    return;
}

static gboolean
on_render(GtkGLArea *area, GdkGLContext *context) {
  glClearColor (0, 0, 0, 0);
  glClear (GL_COLOR_BUFFER_BIT);

  /*draw circle ?*/

  return TRUE;
}

void pointer_motion_event (GtkEventController *gesture,
                           gdouble x, 
                           gdouble y, 
                           gpointer user_data)
{
     GdkModifierType state = gtk_event_controller_get_current_event_state(gesture);
     if (state & GDK_BUTTON1_MASK) {
         g_print ("mouse pointer %0.0f  %0.0fn", x, y);
          xx = (float)x;
          yy = (float)y;
     }
}

static void
activate (GtkApplication* app,
          gpointer        user_data)
{
  GtkWidget *window;
  window = gtk_application_window_new (app);
  gtk_window_set_title (GTK_WINDOW (window), "gtkGL");
  gtk_window_set_default_size (GTK_WINDOW (window), 415, 300);

  GtkWidget *area = gtk_gl_area_new ();
  gtk_window_set_child ((GtkWindow   *)window, area);
  g_signal_connect (area, "realize", G_CALLBACK(on_realize), NULL);
  g_signal_connect (area, "render", G_CALLBACK (on_render), NULL);

    GtkEventController *gesture_pos;
    gesture_pos = gtk_event_controller_motion_new ();
    gtk_widget_add_controller (area, (GtkEventController *)gesture_pos);
    gtk_event_controller_set_propagation_phase((GtkEventController  *)gesture_pos, GTK_PHASE_CAPTURE);
    g_signal_connect (gesture_pos, "motion", G_CALLBACK (pointer_motion_event), area);

  gtk_window_present (GTK_WINDOW (window));
  gtk_widget_show (window);
}


int
main (int    argc,
      char **argv)
{
  GtkApplication *app;
  int status;
  app = gtk_application_new ("org.gtk.example", G_APPLICATION_DEFAULT_FLAGS); 
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);
  return status;
}