Expression for Making a Layer Travel in a Triangle

[Ben Rollason]

The following draws a triangle between the three points defined by three layers. They could equally well be points that you have inputed manually.

The rounded corner thing is tricky. Either the math gets really complicated. You’d need to have a point moving distant from your original point, but perpendicular to it. At each vertex, you would pause the initial movement for a time and instead animate the point in the arc of a circle around the vertex.

How long that time is depends on the relative length of the sides of the triangle to the arcs of the circles.

Like I said, complicated.

Couldn’t you just get the damn thing to follow a spline path? 🙂

-Ben.

http://www.benrollason.com

[Ben Rollason]

Hmmm. I posted the expression in the box, but it didn’t come up, so here it is again…

-Ben.


p1 = thisComp.layer(1).position;
p2 = thisComp.layer(2).position;
p3 = thisComp.layer(3).position;

tpoints = [p1, p2,p3];

tduration = 300; //frames

tFrame = time/thisComp.frameDuration;

tSector = Math.ceil((tFrame) / (tduration/3));

tSector = (tSector < 1?1:(tSector>3?3:tSector));

tBetween = [tSector % 3,tSector -1];

tStage = tFrame % 100;

tP = (tpoints[tBetween[0]]*tStage+ tpoints[tBetween[1]]*(100-tStage))/100;

if (tFrame > tduration) { tP = p1 };

http://www.benrollason.com

[Mark Walczak]

Wow, Ben, that’s really incredible stuff. This is a great help!

I could animate the object with a motion path, but I was looking for a more simple solution (as I need to do all sorts of funky stuff with ramping the rate of travel around the triangle, etc). Also, using an expression forces me to learn the code and sort of reverse-engineer certain scripting concepts, as I am still a novice. Your help is very, very much appreciated.

Also, I checked out your reel and was floored – you have some killer work!

Thanks again, this is very helpful,

Mark

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