LogInThe system was made with UE's Blueprints for a Mortal Engines-inspired game.
To make the AI navigate the roads of the platform, the developer wrote a custom grid-based A* pathfinding algorithm, based on a method shown in this series of tutorials, that the AI uses based on paths and ladders on the crawler they're attached to. All paths and ladders are stored as a grid of vectors, each with a reference of what connections each grid tile can attempt, meaning that ladders allow the AI to move up and down the Z-axis while paths do not.
To prevent AI actors from falling from the crawler, the creator attached them to the component used as the ''root'' for construction when they're spawned in, then only ever moved via relative location.
All the walkable surfaces like buildings, paths, and ladders, can be added and removed in real-time. The author commented that the most challenging moment was getting the order of calculations correct and storing all the data in arrays neatly.
The crawler itself, said the developer, is a custom pawn that aligns itself to the surface through traces from its calculated extremities, based on where blocks are attached to it, and takes its rotation from those same traces and the average of normals from the tracks calculations.
"There's a lot of work to do on the vehicle movement to make it look more physical because I'm faking everything but it's getting there!" commented the author.
In the future, the developer plans to move the system to C++ and share more work-in-progress videos to better showcase this amazing system. You can follow the development process by visiting CommanderHerpDerp01's Reddit page.