3D Sphere OpenGL

Question

I would like to create a Sphere, actually a globe. But i can't seem to find any helpful information about how to handle the vertices and indices to a sphere, how to set them up. Could any of you lead me on to the right track, maybe give me some example code or link to a tutorial?

Answer 1

The easiest thing to do is to use the glu functions. I work mostly in C, but in Java it's probably something like:

import net.java.games.jogl.GL;
import net.java.games.jogl.GLU;
import net.java.games.jogl.GLUquadric;

...

GLUquadric quad = glu.gluNewQuadric();
glu.gluSphere(quad, 2, 10, 15);
glu.gluDeleteQuadric(quad);

This will create a sphere of radius 2, with 10 longitude subdivisions and 15 latitude subdivisions. It will handle creating texture coordinates and proper normals as well.

If you really want to understand how to do the subdivisions and create the spherical approximation yourself, you might look at this code.

Answer 2

Subdivision of an octahredon works pretty well.

Answer 3

import java.awt.Dimension;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.media.opengl.GL;
import javax.media.opengl.GL2;
import javax.media.opengl.GLAutoDrawable;
import javax.media.opengl.GLCapabilities;
import javax.media.opengl.GLEventListener;
import javax.media.opengl.awt.GLJPanel;
import javax.swing.JFrame;


public class Sphere extends GLJPanel implements GLEventListener,KeyListener {

    /**
     * 
     */
    private static final long serialVersionUID = -7419599978736850207L;

    private float rotateX, rotateY, rotateZ;

    public static void main(String[] args) {
        JFrame window = new JFrame("Cube");
        GLCapabilities caps = new GLCapabilities(null);
        Sphere panel = new Sphere(caps);
        window.setContentPane(panel);
        window.pack();
        window.setLocation(50, 50);
        window.setResizable(false);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
        panel.requestFocusInWindow();
    }


    public Sphere(GLCapabilities capabilities) {
        // TODO Auto-generated constructor stub
        super(capabilities);
        setPreferredSize(new Dimension(500, 500));
        addGLEventListener(this);
        addKeyListener(this);
        rotateX = 15;
        rotateY = 15;
        rotateZ = 0;
    }



    void drawSphere(double r, int lats, int longs,GL2 gl) {
                int i, j;
                for(i = 0; i <= lats; i++) {
                    double lat0 = Math.PI * (-0.5 + (double) (i - 1) / lats);
                   double z0  = Math.sin(lat0);
                   double zr0 =  Math.cos(lat0);

                   double lat1 = Math.PI * (-0.5 + (double) i / lats);
                   double z1 = Math.sin(lat1);
                   double zr1 = Math.cos(lat1);

                   gl.glBegin(gl.GL_QUAD_STRIP);
                   for(j = 0; j <= longs; j++) {
                       double lng = 2 * Math.PI * (double) (j - 1) / longs;
                       double x = Math.cos(lng);
                       double y = Math.sin(lng);

                       gl.glNormal3d(x * zr0, y * zr0, z0);
                       gl.glVertex3d(x * zr0, y * zr0, z0);
                       gl.glNormal3d(x * zr1, y * zr1, z1);
                       gl.glVertex3d(x * zr1, y * zr1, z1);
                   }
                   gl.glEnd();
               }
           }

           void computeLocation(GL2 gl) {
               double x = 2 * Math.cos(0);     // my x-, y-, and z-coordinates
               double y = 2 * Math.sin(0);
               double z = 20;
               double d = Math.sqrt(x * x + y * y + z * z); // distance to origin

               gl.glMatrixMode(gl.GL_PROJECTION);        // Set projection parameters.
               gl.glLoadIdentity();
               gl.glFrustum(-d * 0.5, d * 0.5, -d * 0.5, d * 0.5, d - 1.1, d + 1.1);
          }

           public void display(GLAutoDrawable drawable) {

                GL2 gl = drawable.getGL().getGL2();
                gl.glClearColor(0, 0, 0, 0);
                gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);

                gl.glMatrixMode(GL2.GL_PROJECTION);
                gl.glLoadIdentity();
                gl.glMatrixMode(GL2.GL_MODELVIEW);

                gl.glLoadIdentity();

                gl.glRotatef(rotateZ, 0, 0, 1);
                gl.glRotatef(rotateY, 0, 1, 0);
                gl.glRotatef(rotateX, 1, 0, 0);
                gl.glColor3d(1.0, 0.0, 0.0);
                drawSphere(1, 10, 10, gl);

            }

            public void init(GLAutoDrawable drawable) {
                // called when the panel is created
                GL2 gl = drawable.getGL().getGL2();
                computeLocation(gl);
                gl.glEnable(GL.GL_DEPTH_TEST);
            }

            @Override
            public void dispose(GLAutoDrawable drawable) {

            }

            @Override
            public void reshape(GLAutoDrawable drawable, int x, int y, int width,
                    int height) {

            }


            @Override
            public void keyPressed(java.awt.event.KeyEvent e) {
                int key = e.getKeyCode();
                if (key == KeyEvent.VK_LEFT)
                    rotateY -= 15;
                else if (key == KeyEvent.VK_RIGHT)
                    rotateY += 15;
                else if (key == KeyEvent.VK_DOWN)
                    rotateX += 15;
                else if (key == KeyEvent.VK_UP)
                    rotateX -= 15;
                else if (key == KeyEvent.VK_PAGE_UP)
                    rotateZ += 15;
                else if (key == KeyEvent.VK_PAGE_DOWN)
                    rotateZ -= 15;
                else if (key == KeyEvent.VK_HOME)
                    rotateX = rotateY = rotateZ = 0;
                repaint();

            }

            @Override
            public void keyReleased(java.awt.event.KeyEvent e) {
                // TODO Auto-generated method stub

            }

            @Override
            public void keyTyped(java.awt.event.KeyEvent e) {
                // TODO Auto-generated method stub

            }



}