/**
 *   fjenett, february 21st 2005, offenbach-germany
 *   updated 2009-04 for processing 1.0.3.
 *   .. and added centroid dragging.
 *
 *   calculates the centroid of a triangle, probably based on code by p bourke.
 */

XY a,b,c;
int rw = 5, xo, yo;

XY[] tri;
XY triDragged, centroid;

float twothird = 2.0/3.0;

void setup ()
{
    size(200,200);
    
    a = new XY(random(width),10);
    b = new XY(random(width),height/2);
    c = new XY(random(width),height-10);
    tri = new XY[]{a, b, c};
    
    centroid = new XY(-1,-1);
    
    rectMode( CENTER );
    smooth();
}

void draw ()
{
    background(120);
    beginShape(TRIANGLES);
    vertex(a.x,a.y);
    vertex(b.x,b.y);
    vertex(c.x,c.y);
    endShape();
    for (int i=0; i<tri.length; i++) rect(tri[i].x, tri[i].y, rw,rw);

    XY bc = new XY(b.x+(c.x-b.x)/2, b.y+(c.y-b.y)/2);
    centroid.set( int(a.x+(bc.x-a.x)*twothird) , int(a.y+(bc.y-a.y)*twothird) );

    ellipse(centroid.x, centroid.y, rw,rw);
}

void mousePressed ()
{
    triDragged = null;
    for (int i=0; i<tri.length; i++)
        if (tri[i].inside(mouseX, mouseY)) {
            triDragged = tri[i];
        }
    if ( triDragged == null && centroid.inside(mouseX, mouseY) )
        triDragged = centroid;
}

void mouseDragged()
{
    if ( triDragged != null )
    {
        triDragged.x = mouseX;
        triDragged.y = mouseY;
        if ( triDragged == centroid )
        {
            for (int i=0; i<tri.length; i++)
            {
                tri[i].x += mouseX-pmouseX;
                tri[i].y += mouseY-pmouseY;
            }
        }
    }
}

class XY
{
    float x, y;
    
    XY (float xx, float yy)
    {
        x=xx; 
        y=yy;
    }
    
    boolean inside (int xx, int yy)
    { 
        return (xx>x-5 && xx<x+5 && yy>y-5 && yy<y+5); 
    }
    
    void set ( int _x, int _y )
    {
        x=_x; 
        y=_y;
    }
}

/**
 *   fjenett, february 21st 2005, offenbach-germany
 *   updated 2009-04 for processing 1.0.3.
 *
 *   calculates the centroid of a triangle, probably based on code by p bourke.
 */

XY a,b,c;
int rw = 5;

XY[] tri;
XY triDragged;

float twothird = 2.0/3.0;

void setup ()
{
    size(200,200);
    
    a = new XY(random(width),10);
    b = new XY(random(width),height/2);
    c = new XY(random(width),height-10);
    tri = new XY[]{a, b, c};
    
    rectMode( CENTER );
    smooth();
}

void draw ()
{
    background(120);
    beginShape(TRIANGLES);
    vertex(a.x,a.y);
    vertex(b.x,b.y);
    vertex(c.x,c.y);
    endShape();
    for (int i=0; i<tri.length; i++) rect(tri[i].x, tri[i].y, rw,rw);

    XY bc = new XY(b.x+(c.x-b.x)/2, b.y+(c.y-b.y)/2);
    XY centroid = new XY( int(a.x+(bc.x-a.x)*twothird) , int(a.y+(bc.y-a.y)*twothird) );

    ellipse(centroid.x, centroid.y, rw,rw);
}

void mousePressed ()
{
    triDragged = null;
    for (int i=0; i<tri.length; i++)
        if (tri[i].inside(mouseX, mouseY)) {
            triDragged = tri[i];
        }
}

void mouseDragged()
{
    if ( triDragged != null )
    {
        triDragged.x = mouseX;
        triDragged.y = mouseY;   
    }
}

class XY
{
    float x, y;
    
    XY (float xx, float yy)
    {
        x=xx; 
        y=yy;
    }
    
    boolean inside (int xx, int yy)
    { 
        return (xx>x-5 && xx<x+5 && yy>y-5 && yy<y+5); 
    }
}

/*
public String findCentroid()
 {
 int[] x = triangle.xpoints;
 int[] y = triangle.ypoints;
 // construct the medians defined as the line from
 // any vertex to the midpoint of the opposite line
 medians = new Line2D[x.length];
 for(int j = 0; j < x.length; j++)
 {
 int next = (j + 1) % x.length;
 int last = (j + 2) % x.length;
 Point2D vertex = new Point2D.Double(x[j], y[j]);
 // get midpoint of line opposite vertex
 double dx = ((double)x[last] - x[next])/2;
 double dy = ((double)y[last] - y[next])/2;
 Point2D oppLineCenter = new Point2D.Double(x[next] + dx,
 y[next] + dy);
 medians[j] = new Line2D.Double(vertex, oppLineCenter);
 }
 // centroid is located on any median 2/3 the way from the
 // vertex (P1) to the midpoint (P2) on the opposite side
 double[] lengths = getSideLengths();
 double dx = (medians[0].getX2() - medians[0].getX1())*2/3;
 double dy = (medians[0].getY2() - medians[0].getY1())*2/3;
 double px = medians[0].getX1() + dx;
 double py = medians[0].getY1() + dy;
 //System.out.println("px = " + nf.format(px) +
 //                 "\tpy = " + nf.format(py));
 centroid = new Point2D.Double(px, py);
 return "(" + nf.format(px) + ",  " + nf.format(py) + ")";
 }
 */