Need some help drawing a cylinder in openGL

Been a long time since i last posted here. How is everyone hehe.

Lately ive been reading on some openGL stuff and need some help with a simple program. My problem is that i cant get the cylinder to be displayed, i only get 3 warnings but then there is nothing on the screen.

Code:

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#include <stdio.h>
#include <GL/glut.h>


int wf = 1; /*wireframe*/
void display()
{
        /*clear window*/
        glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
        glLineWidth(2.0);
        glColor3f(0.5, 1.0, 0.1);

}
                               
void Idelfunc()
{
        glutPostRedisplay();
}

void  init()
{
        /*set clear color to black*/
        glClearColor (0.0, 0.0, 0.0, 0.0);
        /*set fill color to yellow*/
        glColor3f(0.0, 0.6, 0.9);
        {
                glEnable (GL_DEPTH_TEST);
                glCullFace(GL_BACK);
                glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
        }

        /*Cylinder*/
        {
                void Cylinder (double height, double radius, int slices, int stacks);

                        GLUquadricObj* cyl;
                        cyl = gluNewQuadric();
                        gluQuadricDrawStyle(cyl, GLU_LINE);
                        gluCylinder(cyl, 3, 3, 5, 12, 12);
        }       
       
}

void keys (unsigned char key1, int x, int y)
{
        switch (key1)
        {
                //view in wireframe
        case 'v':
                wf = 1-wf;
                        if (wf)
                                {
                                        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
                                }
                        else
                                {
                                        glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
                                }
                                glutPostRedisplay();
        break;
        case 'q':
        if (key1 =='q' || key1 =='Q' ||key1 =='\27') exit(0);

        }
}

int main( int argc, char** argv)
{
        /*initialize mode and open a window in upper-left corner of screen*/
       
        glutInit(&argc,argv);
        glutInitDisplayMode(GLUT_SINGLE |GLUT_RGB);
        glutInitWindowSize(500, 500);
        glutInitWindowPosition(0,0);
        glutCreateWindow("Cylinder");
        glutDisplayFunc(display);

        init();
//        glutReshapeFunc(myreshape);
        glutIdleFunc(Idelfunc);
        glutKeyboardFunc(keys);
        glutMainLoop();
}

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It does not look like you are actually calling your Cylinder() function during the draw function...

The Cylinder is inside init() and im calling init() on main?

I think you should draw the cylinder right into main.

Code:

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void Cylinder (double height, double radius, int slices, int stacks);

---

As i know, you will use this function to draw a cylinder, like this in main

Code:

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Cylinder(100, 10, 2, 2);

---

When you put init() into main, it did not run the void Cylinder because there is no value pass into it.

Wait.. Why do you need a void Cylinder when you already have a draw cylinder function?

You need to draw the cylinder in the display function.
Your code doesn't make a whole lot of sense really. Why is there a function prototype:

Code:

---

void Cylinder (double height, double radius, int slices, int stacks);

---

but no definition. And why did you put the prototype in the init function? I'm sure it probably compiles fine but it just doesn't make any sense.

Let's say the init() did actually draw you a cylinder. You wouldn't be able to see it because the display function is looped and

Code:

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glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

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Clear's everything that was drawn ready for the next frame so you won't be able to see anything that was drawin in init().