multiphysics_examples

Features

• A barebone [editor_map][./crates/editor_map] to help with level creation.
  • A topography mesh (floor). A parry Heightfield, the crate is here to help with level editing.
  • Initialize a pile of cubes close to the wall for the rock.
  • A point-cloud (or block-model) to represent pile of rock particles.
• A barebone [editor_vehicle][./crates/editor_map] to help with vehicle customization.
  • Loads a .ron file to tweak control settings.
• a sandbox to help with understanding how to wire things together.
  • A model for a bulldozer to push particles into a wall to make the rock pile steeper.
  • A model of a shovel to pick up scoops of rock (for simplicity, once the scoop is picked, the rock particles are just removed and teleported into the truck).
    • Excavator arm initialized with a model. See accessory_controls.
  • Once the truck is full, the user drives it to a muck pile and dumps the material.
  • ui
    • switch between vehicles
    • see how many rocks are in an area (muck piles ; truck ; excavator)
      • See muck_pile.rs and stats_rocks.rs ; <- This is a CPU only implementation.
      • You should export particles positions from GPU if you need that feature.

The project is set up with right-handed Z-up, to the extent possible: as both parry and bevy sometimes expect Y-Up, comments are here to guide you. Models are also Y-up, but children in the hierarchy and rotated locally.

Assets

You're responsible for providing assets in assets/private/ folder.

For practicity, These assets are shared for all projects, through your .env's BEVY_ASSET_ROOT: be sure to adapt .env.example.

Those can't be checked in because of their licences:

• Bulldozer: https://sketchfab.com/3d-models/bulldozer-b06a715d23a7450babac383b8bb7fb0a (glb 1k)
• Excavator: https://www.artstation.com/marketplace/p/A7W15/hydraulic-mining-shovel
  • Bevy doesn't support more than 256 bones so you'll need to remove some (flavor chains are good candidates.)
  • Re-export it to gltf without animations (it reduces its size).
• Truck: undisclosed
  • provided model didn't have a great origin for the bucket to rotate it without mesh interlacing so I modified it.

Opinionated decisions

The project is set up with bevy's recommended optimizations, multi_threaded feature and hot reloading.

A minimal CI from https://github.com/TheBevyFlock/bevy_new_2d, check out their other release scripts!

How to navigate this project ?

Sandbox is the main final project. Run it with cargo run --release -p sandbox.

Let's go through important modules:

Map

shared_map is dedicated to loading a map. You'll probably want to change MapDef to adapt to your requirements.

It supports hot reloading, and you can isolate its behaviour by using editor_map.

sim_data_loader

To load more complex maps, you can use this module, which transforms block models into a digestible format for the shared_map module.

For example, you can invoke a data "migration" with:

cargo run --bin sim_to_mapdef assets/private/Sim\ data/Unbroken\ rock.csv  assets/private/Sim\ data/Broken\ rock.csv assets/private/Sim\ data/transformed/imported_cubes.mapdef.ron`

There is also a visualize example to help with understanding data loading in isolation.

Because of performance issues, you may want to not load all rocks, and group them somehow, check out this rock spawn logic for example.

Vehicles

Shared

shared_vehicle is dedicated to loading and using a vehicle.

shared_vehicle::vehicle_spawner is dedicated to loading the vehicle and setting up their minimal requirements.

shared_vehicle::rapier_vehicle_controller is a thin wrapper around rapier's raycast vehicle controller.

shared_vehicle::accessory_controls is for real-time control of excavator arm or truck dump. "Control" is isolated from the input, so it's easier to create bots or automated behaviour if needed.

The vehicle accessories work by finding the "control" bone and the mesh of the accessory you want to control, then:

• Compute its collider mesh
• Unparent it, but make it follow its "control" bone through KinematicPositionBased
• the accessory controls update the "control" bone rotation.

Editor

editor_vehicle only loads a vehicle, it can be helpful to verify a model loads correctly and inspect it with bevy_editor_egui.

bevy_wgsparkl

Integrates https://github.com/dimforge/wgsparkl into bevy.

Known limitations:

• Doesn't support scene queries (you'd have to reach for gpu data)
• Only 1 upload supported: dynamic shape addition is not yet supported.
• debug mode not supported: launch the app with --release

Sandbox

The sandbox uses the "shared" modules to create a scenario: load a map, load vehicles.

Additionally, more gameplay features are added:

• input is integrated to loaded vehicles
• a loading screen

Collision groups

• Group_2 is used for ground.
• Group_3 is used for excavator parts
• Group_4 is used for truck parts

Limitations

Check out the TODO, FIXME and HACK for limitations, hacks or surprising behaviours.