boolean showVertexIds=true, showVertices=true;
 void myActions() { // actions to be executed at each frame
    if ((mousePressed)&&(keyPressed)) dragPolygon();
   
    stroke(cyan); fill(yellow); drawPolygon(loopIsClosed); noFill();
    if (showVertices) {stroke(orange); fill(white); showPoints(3); noFill(); };
    if (showVertexIds) {fill(dblue); drawPointIDs(); noFill(); };
    
    if ((mousePressed)&&(!keyPressed)) dragAB(); 
    checkAB();
    showAB();
    if (!stabbed(A,B)) {stroke(dblue); A.to(B);} else { stroke(cyan); A.to(B); stroke(blue); A.makeVecTo(B).makeUnit().showArrowAt(A,50); };
     
     //**************************************************************************************************************************
     //******* compute and display point Q where ray(A,B) hits the polygon and the reflection vector R (shown at Q scaled by 50)
     //**************************************************************************************************************************
    } // end my actions