Hello,
I’m new member and as well new to JOGL.
Please help me understand 3D world coordinates for a mouse click using “glu.gluUnProject”.
I followed an example from “Red Book”
( link http://www.java-tips.org/other-api-tips/jogl/how-to-use-gluunproject-in-jogl.html )
To the existing program,
I added 4 points .
Point 1 ( 0, 0, 0 ) Red colored
Point 2 ( 1, 0, 0 ) Green colored
Point 3 ( 0, 0, 1 ) Blue colored
Point 4 ( 1, 0, 1 ) Yellow colored
When I mouse clicked (mouse x=250 and y=250) on Point 1 ( 0, 0, 0 ) Red Colored,
I would like to get world co-ordinates as 0.0, 0.0, 0.0
similarly,
When I mouse clicked on Point 2 ( 1, 0, 0 ) Green Colored,
I would like to get world co-ordinates as 1.0, 0.0, 0.0
When I mouse clicked on Point 3 ( 0, 0, 1 ) Blue Colored,
I would like to get world co-ordinates as 0.0, 0.0, 1.0
When I mouse clicked on Point 3 ( 1, 0, 1 ) Yellow Colored,
I would like to get world co-ordinates as 1.0, 0.0, 1.0
Please help me using proper value of “z”, third parameter on function
glu.gluUnProject((double) x, (double) realy, z, mvmatrix, 0, projmatrix, 0, viewport, 0, wcoord, 0);
Please note:
I used " glu.gluLookAt(0,1,4,0,0,0,0,1,0); "
and a function to draw points which are highlighted in Red color
import java.awt.event.*;
import javax.media.opengl.;
import javax.media.opengl.glu.;
import javax.swing.*;
/**
- When the left mouse button is pressed, this program reads the mouse position
- and determines two 3D points from which it was transformed. Very little is
- displayed.
-
-
@author Kiet Le (Java port)
*/
public class unproject
extends JFrame
implements GLEventListener, KeyListener, MouseListener
{
private GLU glu;
private GLCapabilities caps;
private GLCanvas canvas;
private MouseEvent mouse;
public unproject()
{
super(“unproject”);
caps = new GLCapabilities();
canvas = new GLCanvas(caps);
canvas.addGLEventListener(this);
canvas.addKeyListener(this);
canvas.addMouseListener(this);
getContentPane().add(canvas);
}
public void run()
{
setSize(500, 500);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
canvas.requestFocusInWindow();
}
public static void main(String[] args)
{
new unproject().run();
}
public void init(GLAutoDrawable drawable)
{
GL gl = drawable.getGL();
glu = new GLU();
}
public void display(GLAutoDrawable drawable)
{
GL gl = drawable.getGL();
//gl.glClear(GL.GL_COLOR_BUFFER_BIT);
gl.glClear(GL.GL_COLOR_BUFFER_BIT|GL.GL_DEPTH_BUFFER_BIT);
gl.glLoadIdentity();
glu.gluLookAt(0,1,4,0,0,0,0,1,0);
//Draw Points
drawPoints(drawable);
int viewport[] = new int[4];
double mvmatrix[] = new double[16];
double projmatrix[] = new double[16];
int realy = 0;// GL y coord pos
double wcoord[] = new double[4];// wx, wy, wz;// returned xyz coords
if (mouse != null)
{
int x = mouse.getX(), y = mouse.getY();
System.out.println("\nMouse X = "+x+" Mouse Y = "+y);
switch (mouse.getButton()) {
case MouseEvent.BUTTON1:
gl.glGetIntegerv(GL.GL_VIEWPORT, viewport, 0);
gl.glGetDoublev(GL.GL_MODELVIEW_MATRIX, mvmatrix, 0);
gl.glGetDoublev(GL.GL_PROJECTION_MATRIX, projmatrix, 0);
/* note viewport[3] is height of window in pixels */
realy = viewport[3] - (int) y - 1;
System.out.println("Coordinates at cursor are (" + x + ", " + realy);
glu.gluUnProject((double) x, (double) realy, 0.0, //
mvmatrix, 0,
projmatrix, 0,
viewport, 0,
wcoord, 0);
System.out.println("World coords at z=0.0 are ( " //
+ wcoord[0] + ", " + wcoord[1] + ", " + wcoord[2]
+ ")");
glu.gluUnProject((double) x, (double) realy, 1.0, //
mvmatrix, 0,
projmatrix, 0,
viewport, 0,
wcoord, 0);
System.out.println("World coords at z=1.0 are (" //
+ wcoord[0] + ", " + wcoord[1] + ", " + wcoord[2]
+ ")");
break;
case MouseEvent.BUTTON2:
break;
default:
break;
}
}
gl.glFlush();
}
public void drawPoints(GLAutoDrawable drawable)
{
GL gl = drawable.getGL();
gl.glColor3f(1.0f,0.0f,0.0f);
gl.glPointSize(5.0f);
gl.glBegin(GL.GL_POINTS);
gl.glVertex3f(0.0f,0.0f,0.0f);
gl.glColor3f(0.0f,1.0f,0.0f);
gl.glVertex3f(1.0f,0.0f,0.0f);
gl.glEnd();
gl.glPointSize(1.0f);
gl.glColor3f(0.0f,0.0f,1.0f);
gl.glPointSize(5.0f);
gl.glBegin(GL.GL_POINTS);
gl.glVertex3f(0.0f,0.0f,1.0f);
gl.glColor3f(1.0f,1.0f,0.0f);
gl.glVertex3f(1.0f,0.0f,1.0f);
gl.glEnd();
gl.glPointSize(1.0f);
}
/* Change these values for a different transformation */
public void reshape(GLAutoDrawable drawable, int x, int y, int w, int h)
{
GL gl = drawable.getGL();
gl.glViewport(0, 0, w, h);
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glLoadIdentity();
glu.gluPerspective(45.0, (float) w / (float) h, 1.0, 100.0);
gl.glMatrixMode(GL.GL_MODELVIEW);
gl.glLoadIdentity();
}
public void displayChanged(GLAutoDrawable drawable, boolean modeChanged,
boolean deviceChanged)
{
}
public void keyTyped(KeyEvent key)
{
}
public void keyPressed(KeyEvent key)
{
switch (key.getKeyCode()) {
case KeyEvent.VK_ESCAPE:
System.exit(0);
break;
default:
break;
}
}
public void keyReleased(KeyEvent key)
{
}
public void mouseClicked(MouseEvent e)
{
}
public void mousePressed(MouseEvent e)
{
mouse = e;
canvas.display();
}
public void mouseReleased(MouseEvent e)
{
}
public void mouseEntered(MouseEvent e)
{
}
public void mouseExited(MouseEvent e)
{
}
}
Nick
