Hello there! I was trying to create a 3D rotateable sphere but with a circle attached on its surface. While I managed to accomplish creating a simple sphere with Java OpenGL and rotate it with keyboard input and creating a flat red circle, I have absolutely no clue on combining the two of them together.
So far I get the idea to create another smaller sphere but with different color and overlap it with the bigger, white sphere. But how exactly I should do this?
Here’s what I managed to do so far. If someone can point me in the right direction, I would really appreciate it.
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 float rotateX, rotateY, rotateZ;
public static void main(String[] args) {
JFrame window = new JFrame("Sphere Test");
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
setPreferredSize(new Dimension(400, 400));
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 drawSphere2(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, 1.0, 1.0);
drawSphere(1, 30, 30, gl);
gl.glColor3d(1.0, 0, 0);
drawSphere2(1, 30, 30, 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(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
}
}