If MAME drivers hadn't been written with the mouse in mind,
Although the answer to the true question you ask isn't effected by the incorrectness of this setup supposition, I should point out the supposition is not true.
Mame
can use analog joysticks for lightgun game, as well as lightguns and trackballs and mice. And keyboards and digital sticks. Some people here have made mounted positional gun (aka joysticks) cabs just to play these games, and play them to their satisfaction.
So the "If" should be followed with "MAME hadn't been written with mice, lightguns, analog joysticks, keyboards and digital stick in mind,..."
Again, this doesn't effect the answer, but early posts in this thread make it sound like lightguns have to be mice type inputs.
Not true. (It's just that past joystick lightguns had low accuracy, and the current mouse lightguns work, and the "if it ain't broke..." thinking that make it
falsely seem that all lightguns need to be mice to work well.)
what would stop one from interfacing a console gun with the PC? .... What I'm wondering is since lightgun games are made to work with "raw" lightguns, if we had a "raw" mame driver (read: non mousified), shouldn't you be able to calibrate the gun and use it as normal?? (I should mention I use TV-Out here I think)
I mean, assuming that there's not a contact in the PSX controller port that's only used by lightguns, the data from the sensor has to be going somewhere, right? I suppose the question would be where?
Accuracy, compatabilty, accuracy, and compatibilty. And did I mention accuracy?
First, PSX "raw" lightgun data is different from "raw" arcade data, both which are probably different from "raw" xbox lightgun data. Mame translates standard PC inputs into emulated "raw" arcade lightgun data. So the best way is for the lightgun to be translated to either a mouse type input or an analog joystick type input, and for the accuracy and precision to be high.
Second, I noticed you didn't say the lightgun position (where you shot) calibrated in windows. If it did, mame could see it. That takes both a compatable windows driver and the lightgun sensor properly working. Neither which is a mame issue (mame should stay out of running input devices).
Third, the data is "going" somewhere, but either the adapter doesn't understand, or can't translate it, or translates it poorly to the computer. "Lost in Translation". Again, not a mame thing.
Fourth,
past PC joystick lightguns sucked in accuracy. Not sure if it was old tech or bad drivers or what, but it will take a lot to get past the preconception that joystick lightguns don't work. Oh, and that most games (but not mame, hopefully: see note in first half of this reply) would need to be rewritten to work with the joystick guns.
After that ramble, it raises a question for the guys thinking of writing the interface driver.
Would it be easier to write a joystick driver for the interface board? If the precision is above 3200 per axis, it should work fine in mame. (Even though most analog joysticks output only 256 values, directX directInput's max precision is >64000 (0xffff in hex), and mame's internal precision is twice that.) Hmm, deadzone needs to be zero, and I guess calibration would change the movement saturation level.
Just a thought.