Flowmap Direction

Hi, So I open this topic to get a confirmation of the correct direction of flowmap in Spark AR.

As we all know, the texture coordinate for spark is:
Top left = 0, 0 (black)
Top = 0.5, 0 (dark red)
Top right = 1, 0 (red)
Left = 0, 0.5 (dark green)
Center = 0.5, 0.5 (dark yellow)
Right = 1, 0.5 (orange)
Bottom left = 0, 1 (green)
Bottom = 0.5, 1 (yellowish green)
Bottom right = 1, 1 (yellow)

or like this:

in simplified 3x3:

My question: what should the correct output texture look like when texture coordinate/function vec2 feed the flowmap shader? is it scaling it down or scaling it up?

by scaling up, it means the direction is like this:

by scaling down, it means the direction is like this:

which one is this the correct direction in Spark AR?

In my version, I think it uses flipped y by default since that’s the format that Substance painter uses. If you use the uv coordinates directly in spark, you’ll get a squash/stretch effect.

I suppose I could add a “flip-y” input to it, but for now here’s how to do it: