void scribe(String S) {fill(black); text(S,20,20); noFill();}
void scribe(String S, int i) {fill(black); text(S,20,20+i*20); noFill();}

void mousePressed() { if (mouse().isInWindow()) pickClosestPoint(); else ; } // select closest vertex (see TAB polygon)
  
void keyPressed() {  
  if (key==' ') showHelpText=!showHelpText ; 
  if (key=='X') {String S=" "+"-####.tif"; saveFrame(S);};   ;
  if (key=='?') debugging=true;  // toggle debug mode
  };     

void showHelp() {
    fill(dblue); pushMatrix(); translate(20,20);
     text("Simple Edge/Edge intersection by Jarek Rossignac",0,0); translate(0,20);
     text("    This simplified version assumes general position ",0,0); translate(0,20);
     text("  ",0,0); translate(0,20);
     text("First click in the window to activate it ",0,0); translate(0,20);
     text("Press SPACE to show/hide this help text",0,0); translate(0,20);
     text("Click & drag vertices ",0,0); translate(0,20);
     text("  ",0,0); translate(0,20);
     text("When running Processing (not in a web browser): ",0,0); translate(0,20);
     text("Press 'X' to snap a picture ()",0,0); translate(0,20);
     text("Press '?' to print your debugging stuff",0,0); translate(0,20);
     popMatrix(); noFill();
     showColors();                                                     // showing off various colors (helps you select the one you want)
    }