Example Q, FLTKt and OpenGL without using QOpenGL

[giorgik]

My target is to use QtCreator as IDE and compiler MinGW. Below I command (command line) to successfully compile the file sphere.cpp

C:\Qt\progetti\FLTK\OpenGLSphere>g++ -I C:/MinGW/include -I C:/MinGW/include/FL/images -mwindows -DWIN32 -DUSE_OPENGL32 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -o 'sphere' 'sphere.cpp' -mwindows C:/MinGW/lib/libfltk_gl.a -lglu32 -lopengl32 C:/MinGW/lib/libfltk.a -lole32 -luuid -lcomctl32

C:\Qt\progetti\FLTK\OpenGLSphere>g++ -I C:/MinGW/include -I C:/MinGW/include/FL/images -mwindows -DWIN32 -DUSE_OPENGL32 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -o 'sphere' 'sphere.cpp' -mwindows C:/MinGW/lib/libfltk_gl.a -lglu32 -lopengl32 C:/MinGW/lib/libfltk.a -lole32 -luuid -lcomctl32

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sphere.cpp:

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/glut.H>
#include <FL/gl.h>
#define WIDTH  640
#define HEIGHT 480
//
// Render a simple opengl shaded sphere with a single side light -- erco 11/28/08        
//
//    1.1 Mods to use pure glut calls for subwindow -- erco 03/15/11
//
// You can build this example with: fltk-config --use-glut --compile sphere.cxx
//
 
// GLUT: RESHAPE THE VIEWPORT
void Reshape(int W, int H) {
    // (REFERENCE: SGI light.c DEMO)
    GLfloat ratio = (float)W / (float)H;
    glViewport(0, 0, (GLsizei)W, (GLsizei)H);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-1.5*ratio, 1.5*ratio, -1.5, 1.5, -10.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}
// GLUT: REDRAW THE SCENE
void Redraw() {
    static int valid = 0;
    if (!valid) {
        valid = 1;
        Reshape(WIDTH, HEIGHT);
        // (REFERENCE: SGI 'light.c' EXAMPLE)
        GLfloat mat_ambient[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat mat_diffuse[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat mat_specular[]   = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat light_position[] = { 5.0, 5.0, 0.0, 0.0 };  // XYZ
        glClearColor(0.0, 0.0, 0.4, 0.0);                   // bg color
        glShadeModel(GL_SMOOTH);
        //
        glMaterialfv(GL_FRONT, GL_AMBIENT,   mat_ambient);
        glMaterialfv(GL_FRONT, GL_DIFFUSE,   mat_diffuse);
        glMaterialfv(GL_FRONT, GL_SPECULAR,  mat_specular);
        glMaterialf(GL_FRONT,  GL_SHININESS, 20.0);
        glLightfv(GL_LIGHT0, GL_POSITION, light_position);
        //
        glEnable(GL_LIGHTING);
        glEnable(GL_LIGHT0);
        glEnable(GL_DEPTH_TEST);
    }
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();
        glColor3f(0.5, 0.5, 0.5);
        glutSolidSphere(0.5, 30, 30);
    glPopMatrix();
}
int main(int argc, char *argv[]) {
  Fl_Window win(WIDTH, HEIGHT, "sphere");
  win.resizable(win);
  win.show(argc, argv);
  // Docs say to add glut subwindow /after/ calling win.show()
  win.begin();
    // glutInit(&argc, argv);   // docs say not to call this if a subwindow
    glutInitWindowSize(WIDTH-20, HEIGHT-20);
    glutInitWindowPosition(10,10); // place inside parent window
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_MULTISAMPLE);
    glutCreateWindow("sphere");
    glutReshapeFunc(Reshape);
    glutDisplayFunc(Redraw);
  win.end();
  return(Fl::run());
}

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/glut.H>
#include <FL/gl.h>
#define WIDTH  640
#define HEIGHT 480
//
// Render a simple opengl shaded sphere with a single side light -- erco 11/28/08        
//
//    1.1 Mods to use pure glut calls for subwindow -- erco 03/15/11
//
// You can build this example with: fltk-config --use-glut --compile sphere.cxx
//

// GLUT: RESHAPE THE VIEWPORT
void Reshape(int W, int H) {
    // (REFERENCE: SGI light.c DEMO)
    GLfloat ratio = (float)W / (float)H;
    glViewport(0, 0, (GLsizei)W, (GLsizei)H);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-1.5*ratio, 1.5*ratio, -1.5, 1.5, -10.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}
// GLUT: REDRAW THE SCENE
void Redraw() {
    static int valid = 0;
    if (!valid) {
        valid = 1;
        Reshape(WIDTH, HEIGHT);
        // (REFERENCE: SGI 'light.c' EXAMPLE)
        GLfloat mat_ambient[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat mat_diffuse[]    = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat mat_specular[]   = { 1.0, 1.0, 1.0, 1.0 };  // RGBA
        GLfloat light_position[] = { 5.0, 5.0, 0.0, 0.0 };  // XYZ
        glClearColor(0.0, 0.0, 0.4, 0.0);                   // bg color
        glShadeModel(GL_SMOOTH);
        //
        glMaterialfv(GL_FRONT, GL_AMBIENT,   mat_ambient);
        glMaterialfv(GL_FRONT, GL_DIFFUSE,   mat_diffuse);
        glMaterialfv(GL_FRONT, GL_SPECULAR,  mat_specular);
        glMaterialf(GL_FRONT,  GL_SHININESS, 20.0);
        glLightfv(GL_LIGHT0, GL_POSITION, light_position);
        //
        glEnable(GL_LIGHTING);
        glEnable(GL_LIGHT0);
        glEnable(GL_DEPTH_TEST);
    }
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();
        glColor3f(0.5, 0.5, 0.5);
        glutSolidSphere(0.5, 30, 30);
    glPopMatrix();
}
int main(int argc, char *argv[]) {
  Fl_Window win(WIDTH, HEIGHT, "sphere");
  win.resizable(win);
  win.show(argc, argv);
  // Docs say to add glut subwindow /after/ calling win.show()
  win.begin();
    // glutInit(&argc, argv);   // docs say not to call this if a subwindow
    glutInitWindowSize(WIDTH-20, HEIGHT-20);
    glutInitWindowPosition(10,10); // place inside parent window
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_MULTISAMPLE);
    glutCreateWindow("sphere");
    glutReshapeFunc(Reshape);
    glutDisplayFunc(Redraw);
  win.end();
  return(Fl::run());
}

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In the file sphere.pro as I set to get a successful compilation ?

[wysota]

If you mean that you want to change direct invokation of the compiler into managing your project by qmake then if you want to link an external library to your project, you have to inform qmake about it by modifying the LIBS variable. You can see the compiler invokation qmake does and you can compare it to yours to see the difference. I'm assuming this will be that you are using a static version of the Fltk library in your direct invokation which is not reflected in your qmake project.

[giorgik]

Yes, Fltk libraries are static and therefore should be linked to main.o I was hoping you'd tell me how is the corresponding write sphere.pro known command from the command line with MinGW ...
I'll have to experiment and go trial

[wysota]

It's exactly the same as your direct call. You need to add the same directive you have in your direct invokation to the LIBS variable in the project file (e.g. "LIBS+=C:/MinGW/lib/libfltk_gl.a", etc.)