7d54123303
The `vert0` array, used for parametric vertex coordinates in flexes, is now computed in the flex's local, unrotated frame when using interpolation. This ensures that the parametric coordinates are independent of the flex's initial orientation. A new test confirms that `flex_vert0` is identical for an unrotated and a rotated flex grid. PiperOrigin-RevId: 908196464 Change-Id: I47d6bcc2bc5df581479d485480e0e947ec6d3ffd