CODEWITHSUNDEEP
c++opengl
lapots
lapots

Reputation: 13415

glut window shows nothing

I'm trying to create a simple project using freeglut. Well all my previous projects were working before but new one shows nothing in window. I don't understand why.

There I initialize glut

int main(int argc, char* argv[])
{
    cout<<"Initializing project...."<<endl;

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA | GLUT_MULTISAMPLE);
    glutInitContextVersion(3, 3);
    glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_GLUTMAINLOOP_RETURNS);
    glutInitContextFlags(GLUT_COMPATIBILITY_PROFILE);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(800, 800);
    glutCreateWindow("PROJECT");

    glewExperimental = true; 
    if (glewInit() != GLEW_OK) {
        fprintf(stderr, "Failed to initialize GLEW\n");
        return -1;
    }

    if (glewIsSupported("GL_VERSION_3_3"))
        cout<<"SUCCESS: Opengl 3.3 supported"<<endl;
    else {
        cout<<"FAIL: Opengl 3.3 not supported"<<endl;
        getchar();
        return 1;
    }

    glViewport(0, 0, 800, 800);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();    
    gluPerspective(45.0f, 1.0, 0.5f ,150.0f);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glClearColor(0.0, 0.0, 0.0, 1.0);

    glutSetCursor(GLUT_CURSOR_NONE);

    cout<<"INIT: functions binding....";
    glutDisplayFunc(render);
    glutIdleFunc(render);
    cout<<"SUCCESS"<<endl;

    cout<<"GLUT STARTS NOW!"<<endl;

    glutMainLoop();

    cout<<"GLUT WINDOW CLOSED!"<<endl;
    cout<<"Cleaning...."<<endl;

    cout<<"Press any ENTER to exit..."<<endl;
    getchar();

    return 0;
}

function render looks like this

void render()
{
    glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    glBegin(GL_LINES);
    glColor3f(1.0, 0.0, 1.0);
    glVertex3f(0.1, 0, 0);
    glVertex3f(0.1, 0.5, 0);
    glVertex3f(0.5, 0.5, 0);
    glVertex3f(0.5, 0.0, 0);
    glEnd();

    glutSwapBuffers();
}

But it shows nothing. What is the problem?

Upvotes: 0

Views: 594

Answers (1)

starrify
starrify

Reputation: 14781

The 3rd and 4th parameters of gluPerspective means the zNear and zFar for clipping. As you're setting it to 0.5~150, the z-value you pass to glVertex3f shall be changed since in OpenGL we're looking into the negative direction of Z by default. You may try something like glVertex3f(0.1, 0.5, -10)
Also, on my platform I must also comment this line glutInitContextVersion(3, 3); to make it working. That's an extension of freeglut and I rarely use that in my experiences. Maybe you could also remove that line without affecting your final results.

Upvotes: 1

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