Modifying and Manipulating a interactive bezier curve
- by rachel
This is a homework question and I'm having a lot of trouble with it - I've managed to do some of it but still cant finish it - can i Please get some help.
Q1. Bezier Curves
The following example allows you to interactively control a bezier curve by dragging the control points Cubic.java
Replace the call to draw the cubic shape (big.draw(cubic)), by your own function to draw a bezier by the recursive split method. Finally, add the ability to create a longer Bezier curve by adding more control points to create a second curve.
Cubic.java
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.applet.Applet;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
public class Cubic extends JApplet{
static protected JLabel label;
CubicPanel cubicPanel;
public void init(){
//Initialize the layout.
getContentPane().setLayout(new BorderLayout());
cubicPanel = new CubicPanel();
cubicPanel.setBackground(Color.white);
getContentPane().add(cubicPanel);
label = new JLabel("Drag the points to adjust the curve.");
getContentPane().add("South", label);
}
public static void main(String s[]) {
JFrame f = new JFrame("Cubic");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
});
JApplet applet = new Cubic();
f.getContentPane().add(applet, BorderLayout.CENTER);
applet.init();
f.setSize(new Dimension(350,250));
f.setVisible(true);
}
}
class CubicPanel extends JPanel implements MouseListener, MouseMotionListener{
BufferedImage bi;
Graphics2D big;
int x, y;
Rectangle area, startpt, endpt, onept, twopt, rect;
CubicCurve2D.Double cubic = new CubicCurve2D.Double();
Point2D.Double start, end, one, two, point;
boolean firstTime = true;
boolean pressOut = false;
public CubicPanel(){
setBackground(Color.white);
addMouseMotionListener(this);
addMouseListener(this);
start = new Point2D.Double();
one = new Point2D.Double();
two = new Point2D.Double();
end = new Point2D.Double();
cubic.setCurve(start, one, two, end);
startpt = new Rectangle(0, 0, 8, 8);
endpt = new Rectangle(0, 0, 8, 8);
onept = new Rectangle(0, 0, 8, 8);
twopt = new Rectangle(0, 0, 8, 8);
}
public void mousePressed(MouseEvent e){
x = e.getX();
y = e.getY();
if(startpt.contains(x, y)){
rect = startpt;
point = start;
x = startpt.x - e.getX();
y = startpt.y - e.getY();
updateLocation(e);
}
else if(endpt.contains(x, y)){
rect = endpt;
point = end;
x = endpt.x - e.getX();
y = endpt.y - e.getY();
updateLocation(e);
}
else if(onept.contains(x, y)){
rect = onept;
point = one;
x = onept.x - e.getX();
y = onept.y - e.getY();
updateLocation(e);
}
else if(twopt.contains(x, y)){
rect = twopt;
point = two;
x = twopt.x - e.getX();
y = twopt.y - e.getY();
updateLocation(e);
} else {
pressOut = true;
}
}
public void mouseDragged(MouseEvent e){
if(!pressOut) {
updateLocation(e);
}
}
public void mouseReleased(MouseEvent e){
if(startpt.contains(e.getX(), e.getY())){
rect = startpt;
point = start;
updateLocation(e);
}
else if(endpt.contains(e.getX(), e.getY())){
rect = endpt;
point = end;
updateLocation(e);
}
else if(onept.contains(e.getX(), e.getY())){
rect = onept;
point = one;
updateLocation(e);
}
else if(twopt.contains(e.getX(), e.getY())){
rect = twopt;
point = two;
updateLocation(e);
}
else {
pressOut = false;
}
}
public void mouseMoved(MouseEvent e){}
public void mouseClicked(MouseEvent e){}
public void mouseExited(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void updateLocation(MouseEvent e){
rect.setLocation((x + e.getX())-4, (y + e.getY())-4);
point.setLocation(x + e.getX(), y + e.getY());
checkPoint();
cubic.setCurve(start, one, two, end);
repaint();
}
public void paintComponent(Graphics g){
super.paintComponent(g);
update(g);
}
public void update(Graphics g){
Graphics2D g2 = (Graphics2D)g;
Dimension dim = getSize();
int w = dim.width;
int h = dim.height;
if(firstTime){
// Create the offsecren graphics to render to
bi = (BufferedImage)createImage(w, h);
big = bi.createGraphics();
// Get some initial positions for the control points
start.setLocation(w/2-50, h/2);
end.setLocation(w/2+50, h/2);
one.setLocation((int)(start.x)+25, (int)(start.y)-25);
two.setLocation((int)(end.x)-25, (int)(end.y)+25);
// Set the initial positions of the squares that are
// drawn at the control points
startpt.setLocation((int)((start.x)-4), (int)((start.y)-4));
endpt.setLocation((int)((end.x)-4), (int)((end.y)-4));
onept.setLocation((int)((one.x)-4), (int)((one.y)-4));
twopt.setLocation((int)((two.x)-4), (int)((two.y)-4));
// Initialise the CubicCurve2D
cubic.setCurve(start, one, two, end);
// Set some defaults for Java2D
big.setColor(Color.black);
big.setStroke(new BasicStroke(5.0f));
big.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
area = new Rectangle(dim);
firstTime = false;
}
// Clears the rectangle that was previously drawn.
big.setColor(Color.white);
big.clearRect(0, 0, area.width, area.height);
// Set the colour for the bezier
big.setPaint(Color.black);
// Replace the following line by your own function to
// draw the bezier specified by start, one, two, end
big.draw(cubic);
// Draw the control points
big.setPaint(Color.red);
big.fill(startpt);
big.setPaint(Color.magenta);
big.fill(endpt);
big.setPaint(Color.blue);
big.fill(onept);
big.setPaint(new Color(0, 200, 0));
big.fill(twopt);
// Draws the buffered image to the screen.
g2.drawImage(bi, 0, 0, this);
}
/* Checks if the rectangle is contained within the applet
* window. If the rectangle is not contained withing the
* applet window, it is redrawn so that it is adjacent to the
* edge of the window and just inside the window. */
void checkPoint(){
if (area == null) {
return;
}
if((area.contains(rect)) && (area.contains(point))){
return;
}
int new_x = rect.x;
int new_y = rect.y;
double new_px = point.x;
double new_py = point.y;
if((rect.x+rect.width)>area.getWidth()){
new_x = (int)area.getWidth()-(rect.width-1);
}
if(point.x > area.getWidth()){
new_px = (int)area.getWidth()-1;
}
if(rect.x < 0){
new_x = -1;
}
if(point.x < 0){
new_px = -1;
}
if((rect.y+rect.width)>area.getHeight()){
new_y = (int)area.getHeight()-(rect.height-1);
}
if(point.y > area.getHeight()){
new_py = (int)area.getHeight()-1;
}
if(rect.y < 0){
new_y = -1;
}
if(point.y < 0){
new_py = -1;
}
rect.setLocation(new_x, new_y);
point.setLocation(new_px, new_py);
}
}
