• Adobe After Effects Expressions

  Out of range error with layer index

  Posted by Eva Lepik on May 15, 2017 at 8:24 am

  Hey,

  I am trying to link camera’s focus distance to a chosen layer.
  The layer can be chosen (and keyframed) with a slider.

  I have also added a Math.round expression to controller slider.
  But the expression below gives Out of range error, and I can’t understand why.

  Could anybody show me where the mistake is?
  Thanks!

  Eva

  n = thisComp.layer("CONTROLS").effect("Focus on layer")("Slider"); // Math.round expression is added to slider
Z = thisComp.layer(n).transform.position[2];

  Z-(thisComp.layer("Cam control").transform.position[2])

  Eva Lepik replied 9 years ago 2 Members · 4 Replies
• 4 Replies

• 

  Steve Sierra

  May 15, 2017 at 9:20 am

  Hi,

  You can’t have n = 0, since it is used as the layer index in Z (indexes start at 1).
  What happens when your (“Focus on Layer”) slider hits 0 ?

  I think you should do an if/else statement to set a default value to your focal distance when the slider is at 0.

  Hope this helps ????

  Cheers !
• 

  Eva Lepik

  May 15, 2017 at 9:42 am

  Hi Steve,

  Thanks for the reply.
  I put this expression to slider to avoid it hits 0, and this seems to work ok (below).

  That’s why I don’t understand the reason it gives me ‘out of range’ error.
  Right now the slider value is 6, and still the error is there.

  Regards,

  Math.round(clamp(value, min=5, max=thisComp.numLayers));
• 

  Steve Sierra

  May 15, 2017 at 10:53 am

  Hi again,

  Try putting your clamp in your n variable…

  n = clamp(thisComp.layer(“CONTROLS”).effect(“Focus on layer”)(“Slider”), 5, thisComp.numLayers);
  Z = thisComp.layer(n).transform.position[2];

  Z-(thisComp.layer(“Cam control”).transform.position[2])

  Cheers !
• 

  Eva Lepik

  May 16, 2017 at 7:37 am

  Hi again Steve,

  Thanks for the advice, that helped!

  But as the resulted animation hold the focus distance until next keyframe (clamped, or maybe this is a wrong word), after trial and error I came up with the expression below:
  This works, also if there are no keyframes on the layer index slider.

  I’m pretty sure it could be shorter or written in a better form, but it seams to hold the focus on the layer on all cases ☺
  Maybe that’s useful for someone else, too.

  Regards,
  Eva

  x = thisComp.layer(2).effect("Focus on layer")("Slider");
n = 0;
try {
if (x.numKeys > 0) { // if there are keyframes
n = x.nearestKey(time).index;
if (x.key(n).time > time) n--;
}
if (n > 0 && x.numKeys >= n+1 ) { // if there is 1 more keyframe after current keyframe
t = time;
tMin = x.key(n).time;
tMax = x.key(n+1).time;
y1 = x.key(n).value;
y2 = x.key(n+1).value;
z1 = thisComp.layer(y1).position[2];
z2 = thisComp.layer(y2).position[2];
CamPos1 = thisComp.layer("Cam control").position.valueAtTime(tMin)[2];
CamPos2 = thisComp.layer("Cam control").position.valueAtTime(tMax)[2];
value1 = z1-(CamPos1); // Z position of layer 1 - Z position of cam
value2 = z2-(CamPos2); // Z position of layer 2 - Z position of cam

  ease(t, tMin, tMax, value1, value2);
}
else if (n > 0 && x.numKeys = n ) { // if this is the last keyframe
y1 = x.key(n).value;
z1 = thisComp.layer(y1).position[2];
CamPos = thisComp.layer("Cam control").position[2];
cameraOption.focusDistance = z1 - CamPos;
}
else {
x = Math.round(clamp (thisComp.layer(2).effect("Focus on layer")("Slider"), 5, thisComp.numLayers));
L = thisComp.layer(x).position[2];
CamPos = thisComp.layer("Cam control").position[2];
L - CamPos
}}
catch (e) {
}


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