Finally I have some time to write some documentation that I previously promised ;) After completing (more or less - there is still room for improvement) vanilla content, since last week I started to upgrade & improve HUDs & HMDs for Jets DLC plane with plenty of features that @Jakub BXBX Horyna implemented into the game recently.
I will begin here with some sample code (which is actually excerpt from Blackfoot config), which should be really useful for anyone willing to learn new features.
General Macros (WIP) - contains macros that are used in most of the HMD/MFD/HUD configs
HUD config - main "class MFD" componenet
excerpt from cfgMagazines - contains mfdElements class
In above example you can observe how new mfdElements class is working inside of magazine. Basically, that it's a MFD inside MFD (MFDception!) which is merged into main MFD if specific magazine is present on the pylon. In that special class, you can create groups, text, polygons, bones & whatever you need - just link in regular MFD. You can have multiple MFD inside single magazine config if it's mounted on different vehicles, with different MFDs. In this case you just need to create new class inside of mfdElements.
Then its matter of simply changing name in pylonIcon group to desired entry.
Example Dynamic Loadout MFD
It's worth to mention that usage of __EVAL preprocesor speeds up evaluation of whole MFD rendering so it's more that recommended to use that when you write some math inside. I also recommend for anyone willing to struggle with HUDs to use macros that I've included in this post - those can literally save thousands of hours! They are especially useful when dealing with parallax effect since you can edit two defines (SizeX10deg & SizeY10deg) in one place to control them all. They are also useful for making circular shapes & I can't imagine now, how I was able to spend whole nights before just to make perfect circle before when power of math was in the reach of hand ;)
For making more complex shapes (like outlines of planes on VTOLs, or missiles on Shikra MFD) I'm using Adobe Illustrator & plugin which exports your current scene to array of points, which after some regex magic are ready to use in Arma.
As a random tip I also recommend to anyone dealing with HUDs to make sure that "weapon" vector is aligned with non-diagetic cursor & position then head of pilot proper place first. Otherwise there is serious risk of pulling your hairs out - don't forget I warned you ;)
For those seeking for even more information please head to below link - I spent some time recently to update it with latest features yet still, for some of them, there is missing description.
HMD was based on the AH64 one and those elements are not existing there too. Personally I would avoid adding all the available elements to all available planes just for sake of "consistency" since it reduce authenticity & unique feeling. Sure, you can say that by the 2035 unification of electronics systems would be much higher (vide how i.e. Ka-52/Mi-28 HMD symbology looks like) than now days, yet I still can safely assume that differences would be still present.
Mi-48 HMD is based on Ka-52/Mi-28 HMD, with some futurized additions. Tried to keep it quite close to it to give it that authentic feeling. I also made that choice due to available space I had on HMD - adding more elements would dangerously get it closer to being cluttered. ps, cm counter should be introduced soon
weird, when I tested it (before introduction of "time" source) it was working out of the box - they had some issues (rounding of time...) yet it was working after all.
Yes, it is possible to use custom controls inside MFD right now - see for more informations https://community.bistudio.com/wiki/setUserMFDvalue
With this scripting command & minor edit to MFD config itself (like i.e. simple replacing condition = "on"; with condition = "on - user0";) it should be possible to write some simple script which would control availability of HMD depending on current helmet on the head. Unfortunately, I don't think such feature will be available for vanila Arma anytime soon yet I can at least cheer you up that such idea is somewhere on our wishlist.