• Adobe After Effects Expressions

  Easy stop roller

  Posted by Davib Le roux on August 29, 2009 at 3:54 pm

  I am having serious trouble making my animation ease from one value to the next.
  I have a layer (called “Numbers”) containing numbers and logos arranged something like this:

  LOGO
  2
  LOGO
  LOGO
  4
  LOGO
  3
  0
  LOGO
  6
  7
  LOGO
  1
  8
  LOGO
  5
  9
  LOGO

  (sorry, didint know how to attach a picture of the layer.)

  this layer moves behind a “window layer” that only allows one number or logo to be displayed at a time. like a slot machine display. so in other words to change the value in the window i must edit the y value of my Numbers layer.

  To do this i have added a slider control to another layer (FaceValue) and used an expression. so if my slider control value is any whole number between 0 and 9, that number will be visible in the “window”. if the slider value is anything other than a whole number between 0 and 9, the value will be moving (wiggle(0.2,10000).

  to animate it i have keyframed the slider values. at 0:00:00 the slider value is 10 and at 0:02:00 the value is the number i want to display (eg 5 or 8 or any number 0-9).

  the problem i have is that the animation goes from wiggling at 50 000 pixels per second, to stopped, without slowing down. i want it to slowdown to a stop. Like a slot machine would do. just dont know how to write the expression. i was thinking a time related expression would help but im no good at expresions. please help.

  x = thisComp.layer("FaceValue").effect("SliderControl")("Slider")
if (x == 1){
400+34
}
else if (x == 2){
233.3+34;
}
else if (x == 3){
838.3+34;
}
else if (x == 4){
131.3+34;
}
else if (x == 5){
-299.7+34;
}
else if (x == 6){
-36.7+34;
}
else if (x == 7){
1011.3+34;
}
else if (x == 8){
-472.7+34;
}
else if (x == 9){
578.3+34;
}
else if (x == 0){
-124.7+34;
}
else if (x == 10){
-182;
}
else if (x == 11){
346;
}
else if (x == 12){
-639;
}
else if (x == 13){
90;
}
else if (x == 14){
-813;
}else{
wiggle(.2,10000);
}

  Filip Vandueren replied 16 years, 8 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Filip Vandueren

  August 31, 2009 at 2:20 pm

  You’re just wiggling to get motion blur ?

  That’ll never work he way you want.

  The easiest way I can think of is to use the offset effect.

  place your layer so it’s centered behind your “window”.
  Apply the distort->offset effect.
  Change the y-value of the offset untill your first logo is in the right position it should be [layerwidth/2 , -slotheight] if that makes sense.

  Add two sliders to this layer named:
  visible slot
  (set this to 1)
  revolutions

  now apply this expression to the offset “shift center to”:
  
numSlots=18;
h=source.height;

  visibleSlot=effect("visible slot")("Slider");
  revolutions=effect("extra revolutions")("Slider");

  y=-(visibleSlot-1)*(h/numSlots)-(h*revolutions);

  value+[0,y]


  Okay, now you can just keyframe from visible slot 1 to visible slot 8 or whatever, and the right one should be in the window.

  next step: motion blur.
  Add a fast blur or box blur set to vertical only and add this expressino to blur amount:
  
effect("Offset")("Shift Center To").speed/25*thisComp.shutterAngle/360;


  but we still need to add extra revolutions to sell the effect. Just keyframe the revolutions slider in whole numbers, every time you kayframe from 1 slot to the next.

  It can be done with an expression too, but that’s a bit more comples, and probably slower to render.

  Let me know if this makes sense to you.

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