mapping cockpit windscreen to get rain:
all is done in zmod2 (bear in mind I haven't had to do this up till now so it's my first attempt and I am sure JDougNY would explain this way better. you're stuck with me so tough luck
:
1. import your windscreen along with windscreen bmt into zmod.
2. create a copy of windscreen material and rename it to sth like "yourcar_windscreen2 Glass"
3. in material editor add rain trail texture (it should be from the car whose wipers you will be using, .e.g. ruf wiper trail) to your original bmt
4. back in main application select only your windscreen (front) (select mode enabled) and assign to it your first windscreen material (the one to which you added rain trail texture)
5. deselect and then select both windows on the sides and now assign to it your second material (with no wiper trails)
6. deselect all and select windscreen only
7. switch to vertices (select mode enabled: you should see green lines coming out of points in vertices)
8. in your back view viewer right click: mapping / edit uv
9. in the new window keep those selected:
aa. Create/edit uv
a. from viewportXY
b. keep old mapping
c. select old mapping
hit OK
10. in one of your viewports select UVmapper and your windscreen and texture should appear. If not pick your material from the available materials.
11. scale, move and rotate the windscreen in uvmapper all the time looking at it in your User and/or 3d viewports until you are satisfied.
12. when all is good you are almost ready to export. Now in your viewports ensure that normals point inwards (see JDougNY's instructions on page 15 here)
13. export this meb to a temporary folder
14. select channel 1.3.0 from the temp meb and paste it into channel 1.3.4 of your original windscreen meb (make sure this channel is still called 1.3.4 and not your copied 1.3.0!)
if rain/wiper trails are wrong size manipulate tile options in mtx as per JDoug's instructions on page 15.
15. create new mtx for your door windows: these won't have wiper trails. see examples in our mods (the naming is similar to what I recommend in point 2 above.
Again, Ive just done it the first time, so there might be a better way but it is what it is.
Now I wish people who already know how to do this helped out new members a bit more. You guys know who you are!
EDIT: Ive just realized your windscreen meb will only reference 1 material so your door windows are screwed. Not sure how to deal with this at this moment. Anybody?
EDIT2: I guess you could export first windscreen just with the added material assigned to your door windows: treat it as your master meb. Then do the uv mapping to the windscreen as described above and paste the new channel as per instructions.