Alright so i've been struggling EVERY TIME to export my car with breaking glass, worked on project few months, came back a year later, missed a lot of infos.
So here, for me, and you guys if you ever struggle again to make those break the right way, a quick reminder;
1- using L0 only:Apply vehicle_generic_glasswindows2 to all your window meshes (can select all using Quadr)
2- Generate new mapping (can select every glasses in one ''Quadr'') over the vehicle_generic_glasswindows2 material,
Note that you'll have to click back NONE and unselect the windows you just Quadr, so in the mapper , select can be use again to select youre mapped geometry.
you can put every pieces you wish to map on one single ''window square'' of the material.
Once you put every geomtry in one vehicle_generic_glasswindows2 square, you can proceed to the next step.
3-Open the material editor, locate vehicle_generic_glasswindows2, on the top right side of the window , click on the ''white board'' icon , a new window will pop, click on ''user defined option'' bar , a tab going to show, write on the bottom box ''Crash'' without the quotes and click add so it can be added to the table.
4-Once that's done unselect again everything in viewport, using NONE and right clicking in viewport, now uncheck L0, click on COL, and select all windows COL.
5- Once that's done select all the windows COL and in the right bar click on properties. Scroll down till you see the ''User definited-options''. Double click in the empty box at its right, and add in the tab ''Crash'' without the quotes and click add, then OK. Then you should see the checkbox checked beside User definited-options and CLICK APPLY, very important.
6.NOW THE MOST FRUSTATING THING I WAS DOING SO IT WAS NOT WORKING:
I was used to export lets say : sentinel_hi.yft , what I was doing wrong is I exported the _hi only, made a copy of it in the folder I exported it, then I was using 2 sentinel_hi.yft, and renamed the second one as sentinel.yft, THAT'S where I was wrong.
SO BASICLY EXPORT YOUR (.yft) IN THE HIERARCHY SENTINEL.YFT AAAAAAAAANNNNNDDD rename it to export as SENTINEL_HI.YFT.
now it works. I lost a whole year trying to figure out what was wrong and why the glasses never breaked.
so yeah... If I can at least help one person out there that had that same exact problem, and never made it, you have the solution now.
so basicly just follow any youtube video, there's a ton now (which didn't have a few years ago), and EXPORT YOUR MODEL in _hi.yft AND in the normal variant .yft
Should work even with only a L0 .