Make sure to install geomerative library in processing (Sketch -> Import Library -> Add Library)

shapeIntersection.pde

import geomerative.*;

RShape shp1;
RShape shp2;
RShape shp3;
RShape cursorShape;

void setup()
{
  size(400, 400);
  smooth();

  RG.init(this);

  shp1 = RShape.createCircle(0,0,100.0);
  shp2 = RShape.createCircle(50,50,100.0);
}

void draw()
{
  background(255);    
  translate(width/2,height/2);

  // Only intersection() does not work for shapes with more than one path
  shp3 = RG.intersection( shp1, shp2 );
  
  strokeWeight( 3 );

  if(mousePressed){
    fill( 0 , 220 , 0 , 30 );
    stroke( 0 , 120 , 0 );
    RG.shape(shp1);

    fill( 220 , 0 , 0 , 30 );
    stroke( 120 , 0 , 0 );
    RG.shape(shp2);
  }
  else{
    fill( 220 );
    stroke( 120 );
    RG.shape(shp3);
  }
}