Hello to all. I found an example of a program that uses the libraries FLTK and OpenGL. These same examples can be used very well in Qt. Below I report the sample project.
OpenGLSphere.pro:
Qt Code: 
  1. QT       += core
  2. QT       -= gui
  3.  
  4. TARGET    = OpenGLSphere
  5. #CONFIG   += console     così non appare la finestra dos
  6. CONFIG   -= app_bundle
  7.  
  8. TEMPLATE = app
  9.  
  10. #------------------------------------------------
  11. #
  12. # Uso librerie FLTK 1.3.1
  13. #
  14. #------------------------------------------------
  15. INCLUDEPATH += C:/MinGW/include \
  16.                C:/MinGW/include/FL/images
  17.  
  18. DEFINES   +=  WIN32 USE_OPENGL32="1" LARGEFILE_SOURCE="1" LARGEFILE64_SOURCE="1"
  19.  
  20. LIBS += -mwindows \
  21.         -L C:/MinGW/lib \
  22.         -lfltk \
  23.         -lfltk_forms \
  24.         -lfltk_gl \
  25.         -lfltk_images \
  26.         -lfltk_jpeg \
  27.         -lfltk_png \
  28.         -lfltk_z \
  29.         -lole32 -luuid -lcomctl32
  30.  
  31. #------------------------------------------------
  32. #
  33. # Uso librerie Gl (OpenGL)
  34. #
  35. #------------------------------------------------
  36. LIBS += -L C:/MinGW/lib \
  37.         #-lglaux \
  38.         -lopenglut \
  39.         -lglu32 \
  40.         -lopengl32 \
  41.         -lwinmm -lgdi32
  42.  
  43.  
  44. SOURCES += main.cpp
  45.  
  46. HEADERS += \
  47.     simple.h
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simple.h:
Qt Code: 
  1. #ifndef SIMPLE_H
  2. #define SIMPLE_H
  3.  
  4. #include <FL/Fl.H>
  5. #include <FL/Fl_Window.H>
  6. #include <FL/glut.H>
  7. #include <FL/gl.h>
  8.  
  9. #define WIDTH  640
  10. #define HEIGHT 480
  11.  
  12. //
  13. // Render a simple opengl shaded sphere with a single side light -- erco 11/28/08
  14. //
  15. //    1.1 Mods to use pure glut calls for subwindow -- erco 03/15/11
  16. //
  17. // You can build this example with: fltk-config --use-glut --compile sphere.cxx
  18. //
  19.  
  20. // GLUT: RESHAPE THE VIEWPORT
  21. void Reshape(int W, int H)
  22. {
  23.     // (REFERENCE: SGI light.c DEMO)
  24.     GLfloat ratio = (float)W / (float)H;
  25.     glViewport(0, 0, (GLsizei)W, (GLsizei)H);
  26.     glMatrixMode(GL_PROJECTION);
  27.     glLoadIdentity();
  28.     glOrtho(-1.5 * ratio, 1.5 * ratio, -1.5, 1.5, -10.0, 10.0);
  29.     glMatrixMode(GL_MODELVIEW);
  30.     glLoadIdentity();
  31. }
  32. // GLUT: REDRAW THE SCENE
  33. void Redraw()
  34. {
  35.     static int valid = 0;
  36.  
  37.     if (!valid)
  38.     {
  39.         valid = 1;
  40.         Reshape(WIDTH, HEIGHT);
  41.  
  42.         // (REFERENCE: SGI 'light.c' EXAMPLE)
  43.         GLfloat mat_ambient[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
  44.         GLfloat mat_diffuse[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
  45.         GLfloat mat_specular[]   = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
  46.         GLfloat light_position[] = { 5.0, 5.0, 0.0, 0.0 };  // XYZ
  47.         glClearColor(0.0, 0.0, 0.4, 0.0);                   // bg color
  48.         glShadeModel(GL_SMOOTH);
  49.  
  50.         //
  51.         glMaterialfv(GL_FRONT, GL_AMBIENT,   mat_ambient);
  52.         glMaterialfv(GL_FRONT, GL_DIFFUSE,   mat_diffuse);
  53.         glMaterialfv(GL_FRONT, GL_SPECULAR,  mat_specular);
  54.         glMaterialf(GL_FRONT,  GL_SHININESS, 20.0);
  55.         glLightfv(GL_LIGHT0, GL_POSITION, light_position);
  56.  
  57.         //
  58.         glEnable(GL_LIGHTING);
  59.         glEnable(GL_LIGHT0);
  60.         glEnable(GL_DEPTH_TEST);
  61.     }
  62.  
  63.     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  64.     glPushMatrix();
  65.     glColor3f(0.5, 0.5, 0.5);
  66.     glutSolidSphere(0.5, 30, 30);
  67.     glPopMatrix();
  68. }
  69.  
  70. #endif // SIMPLE_H
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main.cpp:
Qt Code: 
  1. #include "simple.h"
  2.  
  3. int main(int argc, char *argv[])
  4. {
  5.     Fl_Window win(WIDTH, HEIGHT, "sphere");
  6.     win.resizable(win);
  7.     win.show(argc, argv);
  8.  
  9.     // Docs say to add glut subwindow /after/ calling win.show()
  10.     win.begin();
  11.  
  12.     // glutInit(&argc, argv);   // docs say not to call this if a subwindow
  13.     glutInitWindowSize(WIDTH - 20, HEIGHT - 20);
  14.     glutInitWindowPosition(10, 10); // place inside parent window
  15.     glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_MULTISAMPLE);
  16.     glutCreateWindow("sphere");
  17.     glutReshapeFunc(Reshape);
  18.     glutDisplayFunc(Redraw);
  19.     win.end();
  20.     return(Fl::run());
  21. }
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This code fails to compile in MinGW fine, but if I try to do it in the ide QtCreator 2.6.0 fails as it finds defined 2 functions:
Qt Code: 
  1. glut_compatability.cxx:-1: error: undefined reference to `Fl::remove_idle(void (*)(void*), void*)'
  2. glut_compatability.cxx:-1: error: undefined reference to `Fl::add_idle(void (*)(void*), void*)'
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Can you help me solve this problem ?