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 06302010, 02:42 PM #1Member
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Help with mouse moving object and colisions
Hello I'm having a problem in my programing, i drag a ball with mouse and i when it colides with other ball it stays there and don't overlap it and i don't know how to do it, can anyone help me?
Java Code:package BinarySearchT; import java.awt.*; import java.awt.event.*; import javax.swing.*; public class DragBallPanel extends JPanel implements MouseListener, MouseMotionListener, KeyListener { private static final int BALL_DIAMETER = 50; // Diameter of ball private static final int BALL_DIAMETER2 = 50; // instance variables /** Ball coords. Changed by mouse listeners. Used by paintComponent. */ private int x1 = 50; // x coord  set from drag private int y1 = 50; // y coord  set from drag private int x2 = 200; // starting x coord for 2nd ball private int y2 = 200; //starting y coord for 2nd ball private int x3 = 75; private int y3 = 150; /** Position in ball of mouse press to make dragging look better. */ private int _dragFromX = 0; // pressed this far inside ball's private int _dragFromY = 0; // bounding box. private int xInsideBall = 0; //coordinates of where the mouse is pressed inside second ball private int yInsideBall = 0; //is pressed inside second ball private int x3InsideBall = 0; //coordinates of where the mouse is pressed inside second ball private int y3InsideBall = 0; //is pressed inside second ball /** true means mouse was pressed in ball and still in panel.*/ private boolean _canDrag = false; private boolean _canDrag2 = false; private boolean _canDrag3 = false; private String TEXT = "Teste"; private String TEXT2 = "Teste2"; private String TEXT3 = "Teste3"; /** Constructor sets size, colors, and adds mouse listeners.*/ public DragBallPanel() { setPreferredSize(new Dimension(400, 400)); setBackground(Color.white); //setForeground(Color.BLUE); // Add the mouse listeners. this.addMouseListener(this); this.addMouseMotionListener(this); // add the keylistener! this.addKeyListener(this); // make sure the panel is focusable setFocusable(true); }//endconstructor /** Ball is drawn at the last recorded mouse listener coordinates. */ public void paintComponent(Graphics g) { super.paintComponent(g); // Required for background. //g.drawRect(x1, y1, 10, 20); g.setColor(Color.DARK_GRAY); g.drawLine(x1+25, y1+45, x2+25, y2); g.drawLine(x1+25, y1+45, x3+25, y3); g.setColor(Color.DARK_GRAY); g.drawOval(x1, y1, BALL_DIAMETER, BALL_DIAMETER); g.drawString(TEXT, x1+10, y1+25); g.drawOval(x2, y2, BALL_DIAMETER2, BALL_DIAMETER2); g.drawString(TEXT2, x2+10, y2+25); g.drawOval(x3, y3, BALL_DIAMETER2, BALL_DIAMETER2); g.drawString(TEXT3, x3+10, y3+25); }//end paintComponent public void mousePressed(MouseEvent e) { int x = e.getX(); // Save the x coord of the click int y = e.getY(); // Save the y coord of the click //bola 1 if (x >= x1 && x <= (x1 + BALL_DIAMETER) && y >= y1 && y <= (y1 + BALL_DIAMETER)) { _canDrag = true; _dragFromX = x  x1; // how far from left _dragFromY = y  y1; // how far from top } else { _canDrag = false; } //bola 2 if(x >= x2 && x <= (x2 + BALL_DIAMETER2) && y >= y2 && y <= (y2 + BALL_DIAMETER2) ) { _canDrag2 = true; xInsideBall = x  x2; yInsideBall = y  y2; } else { _canDrag2 = false; } //bola 3 if(x >= x3 && x <= (x3 + BALL_DIAMETER2) && y >= y3 && y <= (y3 + BALL_DIAMETER2) ) { _canDrag3 = true; x3InsideBall = x  x3; y3InsideBall = y  y3; } else { _canDrag3 = false; } }//end mousePressed public void mouseDragged(MouseEvent e) { double p, p1; p = Math.sqrt(Math.pow((x1  x2), 2) + Math.pow((y1  y2), 2)); p1 = Math.sqrt(Math.pow((x1  x3), 2) + Math.pow((y1  y3), 2)); // True only if button was pressed inside ball. // Ball pos from mouse and original click displacement if (_canDrag) { x1 = e.getX()  _dragFromX; y1 = e.getY()  _dragFromY; x1 = Math.max(x1, 0); x1 = Math.min(x1, getWidth()  BALL_DIAMETER); y1 = Math.max(y1, 0); y1 = Math.min(y1, getHeight()  BALL_DIAMETER); //collision x1  x2 if(p < BALL_DIAMETER ){ System.out.println("collision"); // Don't move the ball off the screen sides x1 = Math.max( x2BALL_DIAMETER, 400  BALL_DIAMETER); //x1 = Math.min(x1, getWidth()  BALL_DIAMETER); // Don't move the ball off top or bottom y1 = Math.max(y2BALL_DIAMETER, 400 BALL_DIAMETER); y1 = Math.min(y1, getHeight()  BALL_DIAMETER); } //collision x1  x3 if(p1 < BALL_DIAMETER){ System.out.println("collision"); x1 = Math.max(x3,getHeight() ); x1 = Math.min(x3,0); y1 = Math.max(y3,getHeight() ); y1 = Math.min(y3,0 ); } this.repaint(); // Repaint because position changed. } if (_canDrag2) { x2 = e.getX()  xInsideBall; y2 = e.getY()  yInsideBall; x2 = Math.max(x2, 0); x2 = Math.min(x2, getWidth()  BALL_DIAMETER2); y2 = Math.max(y2, 0); y2 = Math.min(y2, getHeight()  BALL_DIAMETER2); this.repaint(); // Repaint because position changed. } if (_canDrag3) { x3 = e.getX()  x3InsideBall; y3 = e.getY()  y3InsideBall; x3 = Math.max(x3, 0); x3 = Math.min(x3, getWidth()  BALL_DIAMETER2); y3 = Math.max(y3, 0); y3 = Math.min(y3, getHeight()  BALL_DIAMETER2); this.repaint(); // Repaint because position changed. } }//end mouseDragged public void keyPressed(KeyEvent ke) { System.out.println("key PRESSED"); //int x = e.getX(); // Save the x coord of the click //int y = e.getY(); // Save the y coord of the click int dx = 10; switch (ke.getKeyCode()) { case KeyEvent.VK_LEFT: // move x coordinate left x1 = dx; x1 = Math.max(x1, 0); break; case KeyEvent.VK_RIGHT: // move x coordinate right x1 += dx; x1 = Math.min(x1, getWidth()  BALL_DIAMETER); } this.repaint(); } public void mouseMoved (MouseEvent e) {} // ignore these events public void mouseEntered (MouseEvent e) {} // ignore these events public void mouseClicked (MouseEvent e) {} // ignore these events public void mouseReleased(MouseEvent e) {} // ignore these events public void mouseExited (MouseEvent e) {} // ignore these events public void keyReleased (KeyEvent ke) {} // ignore this junk public void keyTyped (KeyEvent ke) {} // ignore this junk /** Add a main(), to make this an SSCCE. */ public static void main(String[] args) { // DragBallPanel dbp = new DragBallPanel(); // JOptionPane.showMessageDialog(null,dbp); JFrame window = new JFrame(); window.setTitle("Drag Demo"); window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); window.setContentPane(new DragBallPanel()); Dimension minSize = new Dimension(600,480); window.setMinimumSize(minSize); window.pack(); window.show(); } }//endclass DragBallPanel
 06302010, 05:42 PM #2
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Balls are just circles in two dimensions; a circle is defined by its centre C and its radius R. Two circles (C1, R1) and (C2, R2) touch if and only if C1C2 <= R1+R2 where C1C2 is the distance between the two centres. Making them bounce off in the right direction is an entirely different problem.
kind regards,
Jos
 06302010, 06:18 PM #3Member
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Ok, but i can detect if they colide, what i dont know is how they dont overlap.
 06302010, 07:04 PM #4
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 06302010, 07:40 PM #5Senior Member
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Use painter's algorithm
I compiled and ran your code.
It seems to perform some sort of reaction
while the mouse has control over the
'center ball'.
I don't want to study this action.
I'd rather you explain it, if this is
a problem you want help with.
Here is a fix to render a clean
overlap of the images using what
is commonly known as the painter's
algorithm:
Java Code:g.setColor(Color.white); g.fillOval(x1, y1, BALL_DIAMETER, BALL_DIAMETER); g.setColor(Color.DARK_GRAY); g.drawOval(x1, y1, BALL_DIAMETER, BALL_DIAMETER); g.drawString(TEXT, x1+10, y1+25); g.setColor(Color.white); g.fillOval(x2, y2, BALL_DIAMETER2, BALL_DIAMETER2); g.setColor(Color.DARK_GRAY); g.drawOval(x2, y2, BALL_DIAMETER2, BALL_DIAMETER2); g.drawString(TEXT2, x2+10, y2+25); g.setColor(Color.white); g.fillOval(x3, y3, BALL_DIAMETER2, BALL_DIAMETER2); g.setColor(Color.DARK_GRAY); g.drawOval(x3, y3, BALL_DIAMETER2, BALL_DIAMETER2); g.drawString(TEXT3, x3+10, y3+25);
what you want, but it is harmless, and
improves the rendering's aesthetics.
 06302010, 11:16 PM #6how they dont overlap
 07012010, 01:57 PM #7Member
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Thats my problem i dont the balls to do that overlap. I want the balls to dont intersect.
 07012010, 02:00 PM #8i dont the balls to do that overlap
JosAH has given the formula for detecting if the balls touch or overlap.
Stop moving the ball if they touch.
 07012010, 02:15 PM #9Member
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Can you help me with the Stop moving the ball, i dont know how to do it.
 07012010, 02:24 PM #10
Look at the code where the ball is being moved. Test if the new position will touch any of the other balls. If it does, do NOT move the ball.
You'll need a list of the other balls so you can check each ones position. That could be done by having a class for each ball and a method that takes a Ball as arg and returns true if the balls touch.
 07012010, 06:59 PM #11Member
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Tanks for the help, i'm going to trie
 07022010, 12:14 AM #12Senior Member
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If the balls do not overlap,
which do you want them to do?
1. push the other aside
2. slip around the other
3. halt unless pulled away from the other
 07022010, 12:18 AM #13Member
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