import element.*;

public class SmoothRoller
{
    public static double degrees(double r)
        {
            return r/Math.PI*180;
        }
    public static double radians(double d)
        {
            return d*Math.PI/180;
        }
    public static double sqr(double x) { return x*x;} 
    public static void roller(DrawingWindow d,
                              Pt center,
                              double radius,
                              int n,
                              double offsetDegrees)
    // pre: d, center are non-null, n odd and greater than 2
    // post: draws a constant radius disc with n sides,
    //      diameter 2*radius, n sides, rotated offsetDegrees
    {
        double angle;
        int minorDiam = (int)Math.round(radius*Math.sqrt(sqr(1+Math.cos(Math.PI/n))+sqr(Math.sin(Math.PI/n))));
        int x,y;
        int i;

        /*      for (i = 0; i <= n; i++)
        {
            angle = i*360.0/n+offsetDegrees;
            x = (int)Math.round(center.x()+radius*Math.cos(radians(angle)));
            y = (int)Math.round(center.y()+radius*Math.sin(radians(angle)));
            if (i == 0) d.moveTo(x,y);
            else d.lineTo(x,y);
            }*/
        for (i = 0; i < n; i++)
        {
            angle = i*360.0/n+offsetDegrees;
            x = (int)Math.round(center.x()+radius*Math.cos(radians(angle)));
            y = (int)Math.round(center.y()-radius*Math.sin(radians(angle)));
            Arc a = new Arc(x-minorDiam,y-minorDiam,2*minorDiam,2*minorDiam,
                            (int)angle+180-(int)Math.round(90.0/n),
                            (int)Math.round(180.0/n));
            d.fill(a);
        }
    }

    public static void roll(DrawingWindow d, double distance,double radius, int n)
    {
        int minorDiam = (int)Math.round(radius*Math.sqrt(sqr(1+Math.cos(Math.PI/n))+sqr(Math.sin(Math.PI/n))));
        // interior angle between points
        double interior = 2.0*Math.PI/n;
        // angle between two points opposite another
        double exterior = interior/2;
        // angle of rotation of the roller
        double angle = (-Math.PI/2.0)-exterior/2-distance/minorDiam;
        double centAngle;
        int section = (int)(distance/minorDiam/exterior);
        double baseline = d.bounds().center().y()+minorDiam/2;
        double topline = d.bounds().center().y()-minorDiam/2;
        int x,y;
        if (section % 2 == 0)
        {   // rolls along bottom
            centAngle = (distance/minorDiam)%exterior - exterior/2.0;
            y = (int)Math.round(baseline-minorDiam+radius*Math.cos(centAngle));
            double baseDistance = ((int)(distance/exterior/minorDiam/2))*exterior*minorDiam+distance%(exterior*minorDiam);
        
            x = (int)Math.round(baseDistance-radius*Math.sin(centAngle));
        } else {
            // pivots on bottom point
            centAngle = (distance/minorDiam)%exterior - exterior/2.0;
            y = (int)Math.round(baseline-radius*Math.cos(centAngle));
            x = (int)Math.round((((int)(distance/minorDiam/exterior/2))+1)*exterior*minorDiam+radius*Math.sin(centAngle));
        }
        Pt center = new Pt(x,y);
        d.paintMode();
        d.draw(center);
        d.invertMode();
        roller(d,center,radius,n,degrees(angle));
    }


    public static void main(String args[])
    {
        DrawingWindow d = new DrawingWindow(1000,200);
        int i;
        final int N = 3;
        final int n = N;
        
        final double radius = 50.0;
        
        int minorDiam = (int)Math.round(radius*Math.sqrt(sqr(1+Math.cos(Math.PI/n))+sqr(Math.sin(Math.PI/n))));
        roller(d,new Pt(d.bounds().center()),radius,n,0);
        d.awaitMouseClick();
        d.moveTo(0,d.bounds().center().y()-minorDiam/2-1);
        d.line(d.bounds().width(),0);
        d.moveTo(0,d.bounds().center().y()+minorDiam/2);
        d.line(d.bounds().width(),0);
        Rect block = new Rect(-5,d.bounds().center().y()-minorDiam/2-10,10,10);
        d.clear(d.bounds());
        d.invertMode();
        for (i = 0; i < 2*d.bounds().width(); i+=d.mousePressed()?-1:1)
        {
            Pt p = block.center();
            p.x(i);
            block.center(p);
            d.fill(block);
            roll(d,(double)i,50.0,N);
            long stop = 10+System.currentTimeMillis();
            while (System.currentTimeMillis() <= stop);
            d.fill(block);
            roll(d,(double)i,50.0,N);
        }
    }
}
/*
*/