Mass Projectile Subsystem

A projectile runtime built on Unreal's Mass Entity system. Every shot is a few dozen bytes of state simulated on worker threads, so a scene can hold 100,000+ live rounds with gravity, air drag and wind. Flight uses closed-form drag, so trajectories do not change with frame rate. Budgeted swept traces keep collision cost flat under load without tunnelling.

Per-surface ballistics decide whether a round stops, ricochets or punches through. Penetration uses a V50 ballistic limit against the material's real thickness along the shot, and the exit speed follows the Lambert–Jonas residual-velocity model, so every wall bleeds speed and slow exits drop under gravity. Spent rounds fall off hard faces instead of vanishing.

Hits leave hole decals (entry, exit, and a bore on both faces of a through-shot), play per-surface impact sounds, push physics bodies, and raise an authority-only On Projectile Hit event for Apply Damage. Every asset — Niagara systems, decals, sounds, types — is assigned in Project Settings or on the projectile type, and is packaged automatically.

Near misses are heard and felt. When a round's path passes within its type's flyby radius of the camera, a one-shot whiz plays at the closest point of the pass — spatialized, louder the closer it passes, pitch-varied per round, and budgeted so a 20,000-round volley stays readable instead of turning into noise. Your own shots never whiz past you, and every client hears the flybys of every other player's shots. Rifle, shell and plasma whizzes are included; any SoundWave, SoundCue or MetaSound can replace them per type. The same near misses push an air wake that nudges light physics bodies the round never touched.

Multiplayer sends compact, seeded fire events instead of per-projectile state — one event can carry a 20,000-round volley — with client prediction, server validation and late-join catch-up. Tracers, impact bursts and lingering smoke are drawn by a pluggable Niagara visualizer.

Blueprint-first: Spawn Projectiles, the Mass Projectile Fire component and the Mass Projectile Hit component cover weapons and damage without C++. Ships with three projectile types (Rifle, Shell, Plasma), six physical surfaces, a Blueprint demo map, debug drawing (proj.DebugPaths, proj.DebugHits) and full C++ source. Fifteen pages of documentation with step-by-step tutorials are on this site.