I worked on a C++ simulation system that ran orbital planning cycles, using evolutionary algorithms to find optimal trajectories for mission vehicles. I abstracted the minimizer interface so different optimizers could be swapped in, and optimized the algorithms. I added a modular system for features and tests that could be toggled independently, and modernized the config format to JSON. It built with Bazel and ran on an HPC cluster under SLURM.
I was the sole author of the visualizer. It ran in a browser and rendered the earth, trajectories, and points of interest in WebGL, with a scrubbable timeline and a collapsible entity tree. I wrote custom shaders per entity type so scrubbing stayed fast. State was derived from an input JSON file through a chain of transformations, and GL side effects went through Redux so the view stayed in sync. It rendered cones, lines, regions, and planes, had a 2D map mode using Mapbox, and could export itself to a single HTML file with the data included. Documentation was generated by compiling TypeScript types into JSON Schema.
I also built a tool that ran simulations live across a distributed system, using Kafka for transport and protobuf between Python and C++ services, with PostgreSQL underneath and a dashboard for configuring runs and watching results arrive. The team was five to eight people with a lot of ownership.