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.
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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.
