CODEWITHSUNDEEP
c++openglglfwopengl-compat
JTT
JTT

Reputation: 345

How to glutDisplayFunc, glutMainLoop in glfw?

I have a small program using glut and i need for many reasons to use glfw now. Since I have never used glfw I have a lot of problems. The main ones are the functions : glutDisplayFunc, glutReshapeFunc, glutIdleFunc and glutMainLoop. I have just found out that there are no equivalent functions in glfw. How should I modify my program ?

My program is about a cone rotating in 3 dimensions

I have a function displaycone: 

void displayCone(void){

    // clear the drawing buffer.
    glClear(GL_COLOR_BUFFER_BIT);  //

    // set matrix mode
    glMatrixMode(GL_MODELVIEW);
    // clear model view matrix
    glLoadIdentity();
    // multiply view matrix to current matrix
    gluLookAt(3.0, 3.0, 3.0-4.5, 0.0, 0.0,-4.5,0,1,0);

    // ******
    glPushMatrix();


    glTranslatef(0.0, 0.0, -4.5);

    glBegin(GL_LINES);

    glColor3f (1.0, 1.0, 0.0);
    glVertex3f(0.0, 0.0, 0.0);
    glVertex3f(2.0, 0.0, 0.0);

    glColor3f (1.0, 1.0, 0.0);
    glVertex3f(0.0, 0.0, 0.0);
    glVertex3f(0.0, 2.0, 0.0);

    glColor3f (1.0, 1.0, 0.0);
    glVertex3f(0.0, 0.0, 0.0);
    glVertex3f(0.0, 0.0, 2.0);
    glEnd();

    glPopMatrix();

    // clear the drawing buffer.


    // traslate the draw by z = -4.0
    // Note this when you decrease z like -8.0 the drawing will looks far , or smaller.
    glTranslatef(0.0,0.0,-4.5);
    // Red color used to draw.
    glColor3f(0.8, 0.2, 0.1);
    // changing in transformation matrix.
    // rotation about X axis
    glRotatef(xRotated,1.0,0.0,0.0);
    // rotation about Y axis
    glRotatef(yRotated,0.0,1.0,0.0);
    // rotation about Z axis
    glRotatef(zRotated,0.0,0.0,1.0);

    // scaling transfomation
    glScalef(1.0,1.0,1.0);
    // built-in (glut library) function , draw you a Cone.

    // move the peak of the cone to the origin
    glTranslatef(0.0, 0.0, -height);

    glutSolidCone(base,height,slices,stacks);
    // Flush buffers to screen
    // gluLookAt(3,3,3,0,0,-4.5,0,1,0); <----------------------- delete

    glFlush();
    // sawp buffers called because we are using double buffering
    // glutSwapBuffers();

}

a function reshapecone:

void reshapeCone(int x, int y)
{
    if (y == 0 || x == 0) return;  //Nothing is visible then, so return
    //Set a new projection matrix
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    //Angle of view:40 degrees
    //Near clipping plane distance: 0.5
    //Far clipping plane distance: 20.0

    gluPerspective(35.0,(GLdouble)x/(GLdouble)y,0.5,20.0);

    glViewport(0,0,x,y);  //Use the whole window for rendering
}

and a function idleCone: 

void idleCone(void)
{
    for(int j = 1; j<10000 ; j++){
        double i = dati[j+1][0];

        int win = glfwGetWindow();

        if(i == 0.)      break; 

        xRotated = 180/M_PI*(dati[j][0]);
        yRotated = 180/M_PI*(dati[j][1]);
        zRotated = 180/M_PI*(dati[j][2]);

        displayCone();
        xRotated += 0.;
        yRotated += 0.;
        zRotated += 0.;
        displayCone();

    }
}

In my previous program i had in main: 

glfwInit(&argc, argv);
//double buffering used to avoid flickering problem in animation
glutInitDisplayMode(GLUT_SINGLE | GL_RGB);
//glfwInitWindowSize(800,700);

glfwCreateWindow(800,700,"Rotation of the top",NULL,NULL);
glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
xRotated = yRotated = zRotated = 0.0;
xRotated=0.0;
yRotated=0.0;
glClearColor(0.0,0.0,0.0,0.0);

glutDisplayFunc(displayCone);
glutReshapeFunc(reshapeCone);
glutIdleFunc(idleCone);

glutMainLoop();

Upvotes: 1

Views: 1610

Answers (1)

Rabbid76
Rabbid76

Reputation: 210889

When using glfw, then you've to create your own application loop. Note, it is important to to make the OpenGL context current, before calling any OpenGL instruction, by glfwMakeContextCurrent. e.g.:

GLFWwindow *wnd = glfwCreateWindow(800,700,"Rotation of the top",NULL,NULL);
glfwMakeContextCurrent(wnd);

// do the OpenGL initialization
// [...]

while (!glfwWindowShouldClose(wnd))
{
    // do the drawing
    displayCone();

    glfwSwapBuffers(wnd);
    glfwPollEvents();
}

Instead of glutReshapeFunc you can set the size callback by glfwSetWindowSizeCallback: e.g.: 

glfwSetWindowSizeCallback(wnd, reshapeCone);

void reshapeCone(GLFWwindow* window, int x, int y)
{
    // [...]
}

Upvotes: 5

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