2023 · XR Developer — built with one other engineer
Tactical marksmanship — belt count, magnified optic on a vehicle downrange, and a compass carrying a 1.16 m/s wind the round has to be fired through
第1章Chapter 01 — The problem
Live-fire skills without the range
Machine gun handling is taught on real hardware at real ranges: expensive, slow to schedule, and limited to whatever a range can physically stage. The fundamentals a professional is assessed on — zeroing first among them — do not survive an approximation, so a simulator either models the weapon properly or it teaches the wrong thing convincingly.
Mixed reality changes the economics without changing the weapon. The trainee holds the actual gun; only the range is virtual. That buys an effectively unlimited set of scenarios and removes the cost of ammunition and range time, on the condition that it looks and behaves at PC quality rather than standalone-headset quality.
第2章Chapter 02 — What I built
A real weapon, a modelled round
Chroma-key passthrough on Varjo XR-3 against a green screen, so the trainee sees their own hands and the real weapon inside a virtual range. The gun reports trigger and position over a serial link and drives the simulation directly — what gets scored is the shot that was actually taken.
The ballistics are modelled from the round rather than faked at the point of impact: ballistic coefficient, form factor, mass and diameter, with configurable spread, fire modes, and switching between ammunition types. Environments cover the conditions the training has to hold up in — mountain snow through temperate grassland, rocky desert and arctic weather.
On top of that sits the teaching layer: a progression from zeroing through tactical marksmanship, built to specifications the client army set, with every engagement resolving into something a trainer can debrief from.
第3章Chapter 03 — The hard part
Depth, and a checksum nobody documented
Chroma-key itself is not the difficult part. Staging the scene around the green screen is: how far the trainee stands from it decides whether the composite holds, and because the shot has to land where the trainee aimed, depth had to be correct rather than merely convincing.
The harder problem was the hardware protocol. Communication with the weapon ran over packets checksummed with CRC-16 at both ends, across a language gap with the people who built it. Working out the checksum was the kind of problem I had no background in — cryptography was genuinely unfamiliar territory when I started — and until it was solved, nothing the weapon reported could be trusted enough to shoot with.
第4章Chapter 04 — The result
Used to validate skill
A complete mixed-reality machine gun trainer with both instruction and scenario mechanics, used by soldiers and by the trainers assessing them. Every engagement resolves into a debrief with enough detail for a trainer to walk a trainee back through what actually happened.