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[gl4java-usergroup] Adding code to make selections in GL4Java.
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From: R.M. L. <u8...@cs...> - 2002-02-26 12:43:06
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Hello,
I was wondering if anybody could help, I'm trying to make objects
in my applet window selectable ie. to select a sphere to trigger an
event...so far i've been mostly following tutorials to get where i am..i
have an environment where objects can be placed and then rotated, zoomed
around with the mouse and keys. I know that to select the objects it's
something to do with hits, but so far i'm at a loss.
If anybody could point me in the correct direction that would be great.
Below is the basic structure of my applet, without my attempts so far at
selection, which will begin from mouseclicked and trigger a select(float
x, float y) method, but i'm again not sure about the methods (esp GL)
which are required. Many thanks.
//Mark Logan
//Selection of objects in an applet window
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
//Gl4Java classes..get out of red
import gl4java.GLContext;
import gl4java.awt.GLAnimCanvas;
import gl4java.utils.textures.*;
public class Windowt extends Applet {
renderCanvas canvas = null;
//Initialise applet
public void init() {
setLayout(new BorderLayout());//lays applet components out
canvas = new renderCanvas(getSize().width, getSize().height);
canvas.requestFocus();
add("Center", canvas);
}
//Begin the applet
public void start() {
canvas.start(); //Begins canvas animation
}
public void stop() {
canvas.stop();//stops the canvas
}
public void destroy() {
canvas.stop();
canvas.destroy();//destroys canvas
}
private class renderCanvas extends GLAnimCanvas implements
KeyListener,MouseListener, MouseMotionListener {
float xrot = 0.0f;//rotation for x and y
float yrot = 0.0f;
float moveX = 0.0f;//For mouse movements, try as ints
float moveY = 0.0f;
float x = 0.0f;
float y = 0.0f;
float z = -8.0f;
public renderCanvas(int w, int h) {
super(w, h);
addKeyListener(this);
addMouseListener(this);
addMouseMotionListener(this);
}
public void preInit() {
doubleBuffer = true;
stereoView = false;
}
public void init() {
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);//Clears colour, change
background
gl.glClearDepth(1.0);//Clear depth buffer
gl.glDepthFunc(GL_LESS);//Depth test
gl.glEnable(GL_DEPTH_TEST);//enable test of depth
gl.glShadeModel(GL_SMOOTH);//Smooth colour shading
gl.glMatrixMode(GL_PROJECTION);//Projection matrix
gl.glLoadIdentity();//Resets matrix
glu.gluPerspective(45.0f,
(float)getSize().width/(float)getSize().height, 0.1f, 100f);//Calculate
window aspect ratio
gl.glMatrixMode(GL_MODELVIEW);//Model view matrix
}
public void destroy() {
cvsDispose();//Destroys GL context
}
public void reshape(int width, int height)
{
//Might need to change viewport for object selection???
gl.glViewport(0, 0 , width, height);//Reset viewport & perspective
gl.glMatrixMode(GL_PROJECTION);//select proj matrix
gl.glLoadIdentity();//reset proj matrix
glu.gluPerspective(45.0f,
(float)getSize().width/(float)getSize().height,0.1f, 100.0f);//Aspect
ratio of window
gl.glMatrixMode(GL_MODELVIEW);
}
public void display() {//Draw to the canvas
//Changing to implement true camera...
if (glj.gljMakeCurrent(true)==false)
return;//Is GL initialised properly
gl.glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);//Clears
//screen & depth buffer
gl.glLoadIdentity();//Reset view
//Look at this, pan for keys, just sub letters for numbers
//Think x and z in terms of new camera movements
gl.glTranslatef(0.0f, 0.0f, z);//Move into environment
gl.glTranslatef(x, 0.0f, 0.0f);//Strafe
gl.glTranslatef(0.0f, y, 0.0f);//Strafe
gl.glRotatef(xrot,0.0f,1.0f,0.0f);//Rotate on x axis
gl.glRotatef(yrot,1.0f,0.0f,0.0f);//Rotate y..swapped
renderSphereRed(-2.0f, 1.0f, -1.0f);//Wrap bitmaps around
renderSphereBlue(2.0f, 2.0f, 2.0f);//Need morphing operation
renderSphereYellow(2.0f, 4.0f, 5.0f);//?Name convertor needed
gl.glFlush();//Might not be necessary
gl.glEnd();
glj.gljSwap();//Swap buffers
glj.gljFree();
}
private void renderSphereRed(float x, float y, float z) {//Create
sphere
gl.glPushMatrix();
gl.glTranslatef(x,y,z);
long qobj = glu.gluNewQuadric();
glu.gluQuadricOrientation(qobj , GLU_OUTSIDE);
glu.gluQuadricNormals(qobj, GLU_SMOOTH);
gl.glColor3f(1.0f,0.0f,0.0f);//Red
glu.gluQuadricTexture(qobj, false);
glu.gluSphere(qobj, 0.4f, 16, 16);
glu.gluDeleteQuadric(qobj);
gl.glPopMatrix();
}
private void renderSphereYellow(float x, float y, float z)
{//Create sphere
gl.glPushMatrix();
gl.glTranslatef(x,y,z);
long qobj = glu.gluNewQuadric();
glu.gluQuadricOrientation(qobj , GLU_OUTSIDE);
glu.gluQuadricNormals(qobj, GLU_SMOOTH);
gl.glColor3f(1.0f, 1.0f, 0.0f);//Yellow
glu.gluQuadricTexture(qobj, false);
glu.gluSphere(qobj, 0.4f, 16, 16);
glu.gluDeleteQuadric(qobj);
gl.glPopMatrix();
}
private void renderSphereBlue(float x, float y, float z) {//Create
sphere
gl.glPushMatrix();
gl.glTranslatef(x,y,z);
long qobj = glu.gluNewQuadric();
glu.gluQuadricOrientation(qobj , GLU_OUTSIDE);
glu.gluQuadricNormals(qobj, GLU_SMOOTH);
gl.glColor3f(0.0f, 0.0f, 1.0f);//Blue
glu.gluQuadricTexture(qobj, false);
glu.gluSphere(qobj, 0.4f, 16, 16);
glu.gluDeleteQuadric(qobj);
gl.glPopMatrix();
}
//Required for implementation of mouselistener etc...
public void mouseEntered(MouseEvent e) {
Component comp = e.getComponent();
if(comp.equals(this)) {
requestFocus();
}
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {//Find a way to hide the
mouse pointer
moveX = e.getX();//Take new mouse reading
moveY = e.getY();
//Selection here
if ((e.getModifiers() &
InputEvent.BUTTON1_MASK)==InputEvent.BUTTON1_MASK) {
//Test for cursor hiding, hand selector
setCursor( Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
}
}
public void mouseReleased(MouseEvent e) {
setCursor( Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}
public void mouseClicked(MouseEvent e) {
Component comp = e.getComponent();
if(comp.equals(this)) {
requestFocus();
}
}
public void mouseMoved(MouseEvent e) {
}
public void mouseDragged(MouseEvent e) {
//Reposition, for better format.
//Again, rearrange, put in method for both buttons held down and y
coordinate zoom
//Manual zoom....
if ((e.isMetaDown()) & ((e.getModifiers() &
InputEvent.BUTTON1_MASK)==InputEvent.BUTTON1_MASK)) {
setCursor( Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
float newMoveY = e.getY();//Need distance for zoom
//See which feels better for user
z -= newMoveY - moveY;
//Update method
moveY = newMoveY;
}
//Think about proper camera, might need sin methods...
else if (e.isMetaDown()) {
setCursor(
Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));//Find correct method
float newMoveX = e.getX();//Give us new mouse position
float newMoveY = e.getY();
xrot -= newMoveX - moveX;//See which feels better for user
yrot -= newMoveY - moveY;
//Update method
moveX = newMoveX;
moveY = newMoveY;
}
}
//Find actionlistener thing in swing book
public void keyTyped(KeyEvent e) {
//Leave keyboard events out, put mouse in
}
public void keyPressed(KeyEvent e) {
//Ensure initialisation
if (glj.gljMakeCurrent(true)== false)
return;
switch(e.getKeyCode()) {
case KeyEvent.VK_PAGE_UP: {//Move back with page up
z -=0.5f;
break;
}
case KeyEvent.VK_PAGE_DOWN: {//Move forward with pd
z +=0.5f;
break;
}
//Change position, change to strafe
case KeyEvent.VK_UP:{//height
y -=0.1f;
break;
}
case KeyEvent.VK_DOWN:{//height
y +=0.1f;
break;
}//Give a camera like feel
//
case KeyEvent.VK_RIGHT:{//pan
x -=0.1f;
break;
}
case KeyEvent.VK_LEFT:{//pan
x +=0.1f;
break;
}
}
glj.gljFree();
}
public void keyReleased(KeyEvent e) {
}
}
}
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