Just from looking at how AE does it, the math doesn’t seem all that complex. For all the points except the first and last, it looks like you just subtract the previous point from the next point and divide that vector by 6 to get the out tangent of the current point. Then invert that for the in tangent.

If the path is closed, for the first and last point you wrap around. So, for the first point you would subtract the last point from the 2^nd point, divide by 6, etc.

If the path is open, for the first point you would subtract the first point from the second point and divide by 6 for the out tangent and use [0,0] for the in tangent.

Do something similar for the last point.

Dan

Thanks Chris - there is a ton of info on the web about bezier curves and I am getting what the behind the scenes mechanism is doing - but maybe my real question is if I create a spline via a script I want to know how to calculate the in and out tangents to make a spline that mimics the auto bezier path. Is that even possible?

Thanks

Tim T

On May 20, 2018 at 1:22 AM Chris Zwar <AE-List@media-motion.tv> wrote:

Here’s a starting point.

 

http://jamie-wong.com/post/bezier-curves/

 

On 20 May 2018, at 2:39 pm, TIM THIESSEN <AE-List@media-motion.tv> wrote:

 

Can any one direct me to where I can read about calculating the inTangent/outTangents of a path - I want to build a curved path (like auto bezier) but I don't know the math to figure out the in/out Tangents.

 

Thank

Tim T