- add reference point & uv feature for flatten.
- due to first feature, flatten uv now can process more structure of ballance floor, such as looping floor with low edge count.
- give flatten uv 2 different modes.
- original flatten uv method still existed as a scale size mode.
- update README to keep update with plugin design
* refactor Select by Virtools Group section
* add material preset function description
- fix issue about flatten uv may get zero base vector.
- update elements adder menu.
- bump up version to 3.1
- change bl_options and rewrite invoke and draw functions to let floor creating window become more visual. credit: BLumia.
- also change 3ds max align and flatten uv presentation after changing creating floor window.
- seperate icon loader/unload module.
