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Graph Animation Problem
Hello!
I do not have a ton of experience with AE expressions. This may be a simple fix..
I am trying to animate a vertical line across a graph and have an object track the intersection between the two lines. Im having trouble figuring out how to control the x axis independently so that wherever it moves, the y axis tracks the graph line. Maybe there is a way to track the intersection of the two lines? Or another way of approaching the problem?
In my example the blue dot is tracking the graph line, but not tracking the x position of the vertical line. Ideally I would have a rig where I could freely move the vertical line and the dot will follow the intersection.
I searched around and could not find any other threads like this. Would love any input!
Thanks!
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3 Replies
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It’s not particularly simple, but if your graph is a function of x (never loops back so there are multiple values of y for the same x), a binary search like this should work:
x = thisComp.layer("Vertical Line").transform.position[0];
L = thisComp.layer("Graph");
p = L.content("Shape 1").content("Path 1").path;
iterations = 12;
p0 = L.toComp(p.pointOnPath(0));
p1 = L.toComp(p.pointOnPath(1));
if (x < p0[0]){
p0;
}else if (x > p1[0]){
p1;
}else{
lower = 0;
mid = .5;
upper = 1.0;
for ( i = 0; i < iterations; i++){
pCur = L.toComp(p.pointOnPath(mid));
if (pCur[0] == x) break;
if (pCur[0] > x){
upper = mid;
}else{
lower = mid
}
mid = (upper+lower)/2;
}
pCur
}
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Woah, Dan you are a genius. Works like a dream!
Cheers
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