• Adobe After Effects Expressions

  Count bounces of DVD logo

  Posted by Ana Caballero on May 3, 2022 at 10:47 pm

  Hey guys,

  I used the expression for the bouncing DVD logo i found here on CreativeCow.

  I am trying now to add a counter that detects each collision.

  I managed to detect a direction change for my logo, but I am failing at counting the detections without overwriting the added number.

  My set-up looks like this:

  a var switchDirection will look at the position of the logo and switch from 0 to 1 or 1 to 0 each time the direction changes.

  A counter looks at that sswitch and compares the valueAtTime(time) and valueAtTime(time-1) to see if a change happened.

  var sswitch = effect("Switch")("Kontrollkästchen");
  if(sswitch.valueAtTime(time)==sswitch.valueAtTime(time-(1/25))){
  	value;
  } else {
  	value+1
  }

  My problem is now that instead of counting up, the counter is always is setBack to 0 one frame after the direction change.

  I can see why my code doesnt work, but I cant figure out a way to bypass it.

   

  Anyone any idea how to do it?

   

  Thanks in advance.

   

  Filip Vandueren replied 4 years, 4 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Filip Vandueren

  May 4, 2022 at 9:33 am

  Hello Ana,

  I’m assuming you used this expression of mine forma few years ago:

  hSpeed= 1111;
  vSpeed= 345;
  hMargin= 150;
  vMargin= 75;
  cw=thisComp.width - hMargin*2;
  ch=thisComp.height -vMargin*2;
  // calculate the layer moving at a constant speed
  x = value[0] - hMargin + time*hSpeed;
  y = value[1] - vMargin + time*vSpeed;
  // keep the layer in bounds
  x = Math.abs(x);
  x%=2*cw;
  x = x>cw ? (2*cw)-x : x;
  y = Math.abs(y);
  y%=2*ch;
  y = y>ch ? (2*ch)-y : y;
  [x,y]+[hMargin,vMargin]

  You can count the bounces by using similar Math instead of actually look at the values of the keyframes.

  this would work:

  hSpeed= 1111;
  vSpeed= 345;
  hMargin= 150;
  vMargin= 75;
  cw=thisComp.width - hMargin*2;
  ch=thisComp.height -vMargin*2;
  startPos = position.valueAtTime(0);
  // calculate the layer moving at a constant speed
  x = startPos[0] - hMargin + time*hSpeed;
  y = startPos[1] - vMargin + time*vSpeed;
  hBounces = Math.floor(x/cw);
  vBounces = Math.floor(y/ch);
  totalBounces = hBounces + vBounces;

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