Add UV mapping helper.
Add UV mapping helper.

This is useful for mapping video onto e.g. a curved surface mesh (e.g. the side of a ballon)
mltframework/webvfx,rectalogic/webvfx,rectalogic/webvfx,rectalogic/webvfx,mltframework/webvfx,mltframework/webvfx,rectalogic/webvfx