// PictureApplet3.java: Create a Braid picture with three // independent degrees of freedom import java.applet.Applet; import java.awt.*;import java.awt.event.*; import java.util.Random; public class PictureApplet3 extends Applet implements ActionListener { // applet parts Label prompt; private TextField mInput, dInput, sInput; private Button mpButton, dpButton, spButton, mmButton, dmButton, smButton; private Button fill; private double xc = 325, yc = 400; // center of circle private double r = 300; // radius of circle private int m = 7; // number of points around the circle private double alf = 2.0*Math.PI/m; // basic angle around circle private boolean isFilled = true; // points tracing one portion (out of m) private double x1, y1, x2, y2, x3, y3, x4, y4, x5, y5, x6, y6; // extra points used for the calculations private double x7, y7, x8, y8, x9, y9, x10, y10, x11, y11, x12, y12, x13, y13, x14, y14, x15, y15, x16, y16, x17, y17; private double xInter, yInter; // values returned by inter private double space = 0.03; // fraction of r that is space private double delta = 1.0 - (1.0 + space)*Math.cos(alf); //width of braid private double t = (1.0 - delta)*r; // used for calculations private double tp = (1.0 + space)*r; // used for calculations private double tq = (1.0 - delta - space)*r; // used for calculations private int[] xHandle = new int[6]; // used to fill polygon private int[] yHandle = new int[6]; // used to fill polygon public void init() { setBackground(Color.white); prompt = new Label("Points, Delta, Space:"); mInput = new TextField(2); dInput = new TextField(7); sInput = new TextField(7); mpButton = new Button("+P"); dpButton = new Button("+D"); spButton = new Button("+S"); mmButton = new Button("-P"); dmButton = new Button("-D"); smButton = new Button("-S"); fill = new Button("Fill/not"); mInput.setEditable(true); dInput.setEditable(true); sInput.setEditable(true); mInput.addActionListener(this); dInput.addActionListener(this); sInput.addActionListener(this); mpButton.addActionListener(this); dpButton.addActionListener(this); spButton.addActionListener(this); mmButton.addActionListener(this); dmButton.addActionListener(this); smButton.addActionListener(this); fill.addActionListener(this); add(prompt); add(mInput); add(mpButton); add(mmButton); add(dInput); add(dpButton); add(dmButton); add(sInput); add(spButton); add(smButton); add(fill); mInput.setText(m + ""); dInput.setText(shorten(delta + "")); sInput.setText(shorten(space + "")); } // inter: calculate intersection of two lines // point is returned in globals xInter and yInter public void inter(double x1, double y1, double x2, double y2, double u1, double v1, double u2, double v2) { double m; // slope of first line double n; // slope of second line if (Math.abs(x1 - x2) < 0.00000001) { // nearly vertical n = (v2 - v1)/(u2 - u1); xInter = x1; yInter = n*x1 + v1 - n*u1; } else if (Math.abs(u1 - u2) < 0.00000001) { // 2nd line nearly vertical m = (y2 - y1)/(x2 - x1); xInter = u1; yInter = m*u1 + y1 - m*x1; } else { m = (y2 - y1)/(x2 - x1); n = (v2 - v1)/(u2 - u1); if (Math.abs(m - n) < 0.00000001) { System.out.println("Lines nearly parallel"); System.exit(1); } xInter = (v1 - n*u1 - y1 + m*x1)/(m - n); yInter = (m*v1 - m*n*u1 - n*y1 + m*n*x1)/(m - n); } } public void actionPerformed(ActionEvent e) { if (e.getSource() == mInput) { // set new number of points m = Integer.parseInt(e.getActionCommand()); if (m < 5) { m = 5; mInput.setText(m + ""); } alf = 2.0*Math.PI/m; delta = 1.0 - (1.0 + space)*Math.cos(alf); dInput.setText(shorten(delta + "")); } else if (e.getSource() == dInput) { // set new delta value delta = (new Double(e.getActionCommand())).doubleValue(); } else if (e.getSource() == sInput) { // set new space value space = (new Double(e.getActionCommand())).doubleValue(); // delta = 1.0 - (1.0 + space)*Math.cos(alf); // dInput.setText(shorten(delta + "")); } else if (e.getSource() == mpButton) { // increment m m++; alf = 2.0*Math.PI/m; delta = 1.0 - (1.0 + space)*Math.cos(alf); dInput.setText(shorten(delta + "")); mInput.setText(m + ""); } else if (e.getSource() == mmButton) { // decrement m m--; if (m < 5) m = 5; alf = 2.0*Math.PI/m; delta = 1.0 - (1.0 + space)*Math.cos(alf); dInput.setText(shorten(delta + "")); mInput.setText(m + ""); } else if (e.getSource() == dpButton) { // increase delta delta *= (1.0 + space); dInput.setText(shorten(delta + "")); } else if (e.getSource() == dmButton) { // decrease delta delta *= (1.0 - space); dInput.setText(shorten(delta + "")); } else if (e.getSource() == spButton) { // increase space space *= (1.1); sInput.setText(shorten(space + "")); } else if (e.getSource() == smButton) { // decrease space space *= (0.9); sInput.setText(shorten(space + "")); } else if (e.getSource() == fill) { // fill / no fill if (isFilled) isFilled = false; else isFilled = true; } repaint(); } private String shorten(String s) { return s.substring(0, Math.min(7, s.length())); } public void paint(Graphics g) { g.drawString("Points: Number of vertices taken around" + " the circle", 20, 50); g.drawString("Delta: Width of the braid as a fraction of" + " the radius (defaults to maximum value)", 20, 66); g.drawString("Space: Space between braid parts" + " (as a fraction of the radius)", 20, 80); if (delta > 1.0 - (1.0 + space)*Math.cos(alf) || delta < 0.0) { g.setColor(Color.red); g.drawString("WARNING: Delta has meaningless value", 20, 96); } t = (1.0 - delta)*r; tp = (1.0 + space)*r; tq = (1.0 - delta - space)*r; for (int j = 0; j < m; j++) { x10 = tq*Math.cos(alf + j*alf); y10 = tq*Math.sin(alf + j*alf); x11 = tq*Math.cos(3*alf + j*alf); y11 = tq*Math.sin(3*alf + j*alf); x12 = r*Math.cos(2*alf + j*alf); y12 = r*Math.sin(2*alf + j*alf); x13 = t*Math.cos(2*alf + j*alf); y13 = t*Math.sin(2*alf + j*alf); x14 = t*Math.cos(-2*alf + j*alf); y14 = t*Math.sin(-2*alf + j*alf); x15 = r*Math.cos(-2*alf + j*alf); y15 = r*Math.sin(-2*alf + j*alf); x16 = tp*Math.cos(-alf + j*alf); y16 = tp*Math.sin(-alf + j*alf); x17 = tp*Math.cos(alf + j*alf); y17 = tp*Math.sin(alf + j*alf); x1 = r*Math.cos(0 + j*alf); y1 = r*Math.sin(0 + j*alf); // (x2,y2) is inter of 10-11 and 1-12 inter(x10, y10, x11, y11, x1, y1, x12, y12); x2 = xInter; y2 = yInter; x4 = t*Math.cos(0 + j*alf); y4 = t*Math.sin(0 + j*alf); // (x3,y3) is inter of 10-11 and 4-13 inter(x10, y10, x11, y11, x4, y4, x13, y13); x3 = xInter; y3 = yInter; // (x5,y5) is inter of 4-14 and 16-17 inter(x4, y4, x14, y14, x16, y16, x17, y17); x5 = xInter; y5 = yInter; // (x6,y6) is inter of 1-15 and 16-17 inter(x1, y1, x15, y15, x16, y16, x17, y17); x6 = xInter; y6 = yInter; g.setColor(Color.red); if (isFilled) { xHandle[0] = (int)(x1+xc); yHandle[0] = (int)(y1+yc); xHandle[1] = (int)(x2+xc); yHandle[1] = (int)(y2+yc); xHandle[2] = (int)(x3+xc); yHandle[2] = (int)(y3+yc); xHandle[3] = (int)(x4+xc); yHandle[3] = (int)(y4+yc); xHandle[4] = (int)(x5+xc); yHandle[4] = (int)(y5+yc); xHandle[5] = (int)(x6+xc); yHandle[5] = (int)(y6+yc); g.fillPolygon(xHandle, yHandle, xHandle.length); } else { g.drawLine((int)(x1+xc),(int)(y1+yc),(int)(x2+xc),(int)(y2+yc)); g.drawLine((int)(x2+xc),(int)(y2+yc),(int)(x3+xc),(int)(y3+yc)); g.drawLine((int)(x3+xc),(int)(y3+yc),(int)(x4+xc),(int)(y4+yc)); g.drawLine((int)(x4+xc),(int)(y4+yc),(int)(x5+xc),(int)(y5+yc)); g.drawLine((int)(x5+xc),(int)(y5+yc),(int)(x6+xc),(int)(y6+yc)); g.drawLine((int)(x6+xc),(int)(y6+yc),(int)(x1+xc),(int)(y1+yc)); } // end if } // end for } // end paint }