// effect routine

last_letter = numletters - 1;
if (last_letter){
 if (sub_order < 2){
  letter_perc = letter / last_letter;
  if (sub_order == 1) letter_perc = 1 - letter_perc;
 } else if (sub_order < 4){
  my_letter = 2 * letter;
  if (my_letter >= numletters) my_letter = 2 * numletters - my_letter - 2;
  letter_perc = my_letter / last_letter;
  if (sub_order == 3) letter_perc = 1 - letter_perc;
 } else {
  letter_perc = frame / lastsubframe;
 }
 perc = Math.min(1, Math.max(0, 2 * frame / lastsubframe - letter_perc));
} else perc = frame / lastsubframe;
if (reverse_sub_effect == true) perc = 1 - perc;
if (letter % 2) d = -1  else d = 1;
angle = 44 / 7 * perc * d;
rota = max_delta;
tx = Math.sin(angle) * (Math.cos(angle) * (rota * 1.4) - Math.cos(angle * 2) * rota);
ty = Math.sin(angle) * (Math.sin(angle) * (rota * 1.4) - Math.cos(angle * 2) * rota);
tz = Math.sin(angle) * (Math.sin(angle) * (rota * 1.4) - Math.sin(angle * 2) * rota);
if (use_alpha) alpha = perc * 100;
xrotate = tx * (rotations / 4);
yrotate = ty * (rotations / 4);
zrotate = tz * (rotations / 4);
