boolean showHelpText=false;

 void keys() {
  if (key==' ') {showHelpText=!showHelpText;};
  if (key=='a') {threshold=C.average();};
  if (key=='h') {resetView(); };
  if (key=='m')  C.makeMesh(M);
  if (key=='c') {pickS=true;};
  if (key=='v') {printview=true; };
  if (key=='i') {String S="mesh"+"-####.tif"; saveFrame(S);};   
  if (key=='n') {S.next();};  
  if (key=='o') {S.opposite();  };  
  if (key=='p') {S.previous();};  
  if (key=='r') {showRefined=!showRefined; 
    if (showRefined) {M.makeIsosurface(threshold,S); S.init(); for (int i=0; i<4; i++) {S.splitEdges(); S.bulge(); S.splitTriangles(); S.init(); }; }; };  
  if (key=='s') { S.markBorderVertices(); S.computeLaplaceVectors(); S.tuck(0.6); };
  if (key=='t') {S.turn();};  
  if (key=='f') {S.fit(C); for (int i=0; i<3; i++) {S.markBorderVertices(); S.computeLaplaceVectors(); S.tuck(0.5);}; };  
  }

pt Mouse = new pt(0,0,0);                 // current mouse position
float xr, yr = 0;                         // mouse coordinates relative to center of window
int px=0, py=0;                           // coordinats of mouse when it was last pressed