I am having trouble. I need to rotate an equilateral triangle around it's centre by using the drag listener and click listener. The triangle should grow but now change angles and be rotated by a point while being centred at the middle of the triangle. This is my problem, it is currently dragging by the point 3 and rotating around point 1. I have an array of values x and y and it stores 4 values each containing the initial point first at ordinal value 0 and point 1 2 and 3 at the corresponding values.
`
public class DrawTriangle extends JFrame {
enter code here
/** The Constant NUMBER_3. */
private static final int NUMBER_3 = 3;
/** The Constant EQUL_ANGLE. */
@SuppressWarnings("unused")
private static final double EQUL_ANGLE = 1;
/** The Constant TRIANGLE_POINTS. */
private static final int TRIANGLE_POINTS = 4;
/** The Constant _400. */
private static final int SIZE = 400;
/** The x points. */
private int [] xPoints = new int[TRIANGLE_POINTS];
/** The y points. */
private int [] yPoints = new int[TRIANGLE_POINTS];
private int xInitial;
private int yInitial;
/** The x. */
private double x = EQUL_ANGLE;
/** The new x. */
private double newX;
/** The new y. */
private double newY;
/**
* Instantiates a new draw triangle.
*/
public DrawTriangle() {
super("Dimitry Rakhlei");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setContentPane(new DrawTrianglePanel());
setSize(SIZE, SIZE); // you can change this size but don't make it HUGE!
setVisible(true);
}
/**
* The Class DrawTrianglePanel.
*/
private class DrawTrianglePanel extends JPanel implements MouseListener,
MouseMotionListener {
/**
* Instantiates a new draw triangle panel.
*/
public DrawTrianglePanel() {
addMouseListener(this);
addMouseMotionListener(this);
}
/**
* Drawing the triangle.
*
* @param g
* the g
* @see javax.swing.JComponent#paintComponent(java.awt.Graphics)
*/
public void paintComponent(Graphics g) {
super.paintComponent(g);
// DRAWING CODE HERE
g.drawPolygon(xPoints, yPoints, 3);
System.out.println("Paint called");
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseListener#mousePressed
* (java.awt.event.MouseEvent)
*/
public void mousePressed(MouseEvent e) {
System.out.println("Mouse pressed called");
e.getPoint();
xPoints[0] = e.getPoint().x;
yPoints[0] = e.getPoint().y;
repaint();
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseListener#mouseReleased
* (java.awt.event.MouseEvent)
*/
public void mouseReleased(MouseEvent e) {
System.out.println("Mouse released called");
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseMotionListener#mouseDragged
* (java.awt.event.MouseEvent)
*/
public void mouseDragged(MouseEvent e) {
System.out.println("Mouse dragged called");
newX = e.getPoint().x;
newY = e.getPoint().y;
xPoints[1] = (int) newX;
yPoints[1] = (int) newY;
newX = xPoints[0] + (xPoints[1]-xPoints[0])*Math.cos(x) - (yPoints[1]-yPoints[0])*Math.sin(x);
newY = yPoints[0] + (xPoints[1]-xPoints[0])*Math.sin(x) + (yPoints[1]-yPoints[0])*Math.cos(x);
xPoints[2] = (int) newX;
yPoints[2] = (int) newY;
newX = xPoints[0] + (xPoints[1]-xPoints[0])*Math.cos(x) - (yPoints[1]-yPoints[0])*Math.sin(x);
newY = yPoints[0] + (xPoints[1]-xPoints[0])*Math.sin(x) + (yPoints[1]-yPoints[0])*Math.cos(x);
xPoints[3] = (int) newX;
yPoints[3] = (int) newY;
repaint();
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseListener#mouseEntered
* (java.awt.event.MouseEvent)
*/
public void mouseEntered(MouseEvent e) {
System.out.println("Mouse Entered.");
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseListener#mouseExited
* (java.awt.event.MouseEvent)
*/
public void mouseExited(MouseEvent e) {
System.out.println("Mouse exited.");
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseListener#mouseClicked
* (java.awt.event.MouseEvent)
*/
public void mouseClicked(MouseEvent e) {
}
/**
* (non-Javadoc).
*
* @param e
* the e
* @see java.awt.event.MouseMotionListener#mouseMoved
* (java.awt.event.MouseEvent)
*/
public void mouseMoved(MouseEvent e) {
}
}
/**
* The main method.
*
* @param args
* the arguments
*/
public static void main(String[] args) {
new DrawTriangle();
}
};`
My issue is that this code basically runs correctly but I am told the vertex point of rotation has to be in the middle of the triangle. Mine is the first point.
