[Transformer] Overlay rotation around the X and Y axles

[DeweyReed]

Thank you for the excellent work on the transformer! I've learned a lot by reading your code.

Use case description

At the moment, we can only rotate overlays around Z axles. It would be awesome if we could rotate around the other two axles.

Proposed solution

OverlayMatrixProvider is where the calculation happens. It looks very complicated and intimidating to me.

[tof-tof]

Thanks for you comments! Nice to see the work is appreciated.

Spinning around the x or y axis would be a 3D customization, and we don't support those in overlays sadly as we found combining different geometric operations didn't work as well as we'd hoped in would as the aspect ratio was often a little off.

In Media3 version 1.1.1 we supported defining your own transformation matrix. You could play around with that version and that api and see if you can get a lateral or vertical rotations working that by the gl matrices yourself and passing it in. We have a 3D spin effect that can show you what matrices are involved in creating a rotation around y axis. If the setMatrix() api proves useful then we may consider bringing it back in another form.

[DeweyReed]

Thank you for the quick reply and explanation! The repo is full of precious code! I'll try those APIs and report back here if I can pull it off. :D

[tof-tof]

just went through the API and realised there is this method in the Overlay base class TextureOverlay: https://github.com/androidx/media/blob/d13a0f4ec62ca092b79746a5725b62a3244cc5b4/libraries/effect/src/main/java/androidx/media3/effect/TextureOverlay.java#L55

if the matrix you can get a 3D spin matrix working, you can input it there to have it applied on the Overlay

In summary, this can be solved with the current API. Hope this helps!