Sine wave

[colin shuker]

Hi, I'm trying to draw a sine wave, with a thickness of about 3.

When I draw it, the curve never comes out smooth, even with antialiasing turned on.

I've tried drawing lots of line segments, using ovals, and also polygons. but none of them come out smooth...
You can always see like a ladder effect along the curve close up.

Can anyone help me do this? Thanks very much.

[Maneesh Godbole]

How about showing us some code.

[colin shuker]

Ok then..

package banner;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.LinkedList;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
import mathtab.ImageUtils;

/**
 *
 * @author root
 */
class Drawer extends JPanel
{
    BufferedImage mathImg = ImageUtils.convertToBuff(ImageUtils.getImage("images/math.png"));
    BufferedImage backImg = ImageUtils.convertToBuff(ImageUtils.getImage("images/back.png"));
    BufferedImage tuteImg = ImageUtils.convertToBuff(ImageUtils.getImage("images/tuition.png"));
    BufferedImage dotImg = ImageUtils.convertToBuff(ImageUtils.getImage("images/blackdot.png"));
    
    public Drawer()
    {
        this.setPreferredSize(new Dimension(990,120));
        
        
    }
    
    
    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        
        BufferedImage buff = new BufferedImage(990,120,2);
        
        Graphics2D g2 = (Graphics2D)buff.getGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.BLACK);
        for(int lp=0;lp<120;lp++)
        {
            g2.drawImage(backImg, 0,lp, this);
        }
        
        g2.drawImage(mathImg, 20,15 , this);
        
        g2.drawImage(tuteImg, 345,67-15 , this);
        
        
        
        g2.setStroke(new BasicStroke(3.0f));//, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
        double f0 = 0.85;
        double f1 = 0.94;
        double amp = 43;
        double xfactor = 100;
        double x0 = -f0*Math.PI;
        double x1 = f1*Math.PI;
        int n = 5000; // 10 points, 9 lines
        
        LinkedList<Point> points = new LinkedList<Point>();
        for(int lp=0;lp<n;lp++)
        {
            double x = x0+lp*(x1-x0)/(n-1);
            System.out.println("x="+x);
            
            //if(xfactor*x-(int)(xfactor*x)<0.1)
            //{
            
            double xdiff = 0;//xfactor*x-(int)(xfactor*x);
            double ydiff = amp*Math.sin(x)-(int)(amp*Math.sin(x));
            if(-0.05<xdiff && xdiff<0.05 && -0.05<ydiff && ydiff<0.05)
            {
                points.add(new Point((int)(xfactor*x), -(int)(amp*Math.sin(x))));
            }
            
            
            
            
            
        }
        
        int xs = 305;
        int ys = 59;
        int len = points.size();
        for(int lp=1;lp<len;lp++)
        {
            g2.drawLine(points.get(lp-1).x+xs, points.get(lp-1).y+ys, points.get(lp).x+xs, points.get(lp).y+ys);
            //g2.fillOval(points.get(lp).x+xs, points.get(lp).y+ys,5, 5);
            
            //g2.drawImage(tuteImg, points[lp].x+xs, points[lp].y+ys , 5,5,this);
        }
        //g2.fillOval(200,30,50,50);
        
        int[] xx = new int[len];
        int[] yy = new int[len];
        for(int lp=0;lp<len;lp++)
        {
            xx[lp] = points.get(lp).x + xs;
            yy[lp] = points.get(lp).y + ys;
        }
        
        g.drawImage(buff, 0, 0 ,null);
        try
        {
            ImageIO.write(buff, "png",new File("BANNER.png"));
            //g2.fillPolygon(xx, yy, len);
        } catch (IOException ex)
        {
            Logger.getLogger(Drawer.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

Its a bit messy, hope that helps>

[colin shuker]

Nevermind, I just used a cubic bezier curve, makes it look better, so I don't need the sinewave now. Thanks

[Campbell Ritchie]

Does a Bezier curve match a sine wave? Show us how.

[colin shuker]

Its close enough