Hello all,

I am trying to figure out manually, the point `p`

at which the layer will be present at a given time `t`

. Consider I have a `star`

layer and it’s origin is animated from `(0, 0)`

to `(60, 0)`

. The interpolation type is `linear`

. So according to the `Synfig`

code, the `in-tangent`

and `out-tangent`

both will be equal to `60`

. But these needs to be scaled by a factor of 3.

So finally, to calculate the `hermite curve`

, we need 4 control points(link).

So, for the hermite curve of `x-axis`

:

`P0`

= 0

`P1`

= 60/3 = 20

`P2`

= 60/3 = 20

`P3`

= 60

Hence the curve will be written as:

P(t) = (1 - t)^{3} * 0 + 3(1 - t)^{2}t * 20 + 3(1-t)t^{2} * 20 + t^{3} * 60

where 0 < t < 1

Let us take `t = 0.5`

:

P(0.5) = 22.5

This is the answer we get after evaluating the curve. But intuitively and also the value at t = 0.5 in `Synfig`

UI is `30`

.

Could anyone explain where am I wrong here, or where am I making the mistake. I have been stuck on this for quite a while. Any help would be much appreciated!

I am attaching the `.sif`

file here: star_check.sif (2.8 KB)