Demo Scripts

Physics Sandbox includes 22 demo scripts that showcase different physics scenarios. Each demo is available in both F# (.fsx) and Python, with identical behavior.

Running Demos

F# Demos

// Run a single demo:
// dotnet fsi Scripting/demos/Demo01_HelloDrop.fsx

// Run all demos automatically (10s each):
// dotnet fsi Scripting/demos/AutoRun.fsx

// Interactive runner (prompts between demos):
// dotnet fsi Scripting/demos/RunAll.fsx

Python Demos

// Prerequisites: pip install grpcio grpcio-tools protobuf

// Run a single demo:
// python Scripting/demos_py/demo01_hello_drop.py

// Run all demos automatically:
// python Scripting/demos_py/auto_run.py

// Interactive runner:
// python Scripting/demos_py/run_all.py

Demo Catalog

	Name	Description
01	Hello Drop	Single sphere dropped under gravity — the simplest demo
02	Bouncing Marbles	Multiple marbles dropped onto a ground plane
03	Crate Stack	Tower of crates that collapses under gravity
04	Bowling Alley	Bowling ball launched at a row of pins
05	Marble Rain	Random spheres spawned above the ground
06	Domino Row	Line of dominoes knocked over by an impulse
07	Spinning Tops	Bodies with angular velocity (torque applied)
08	Gravity Flip	Gravity direction changes mid-simulation
09	Billiards	Pool table setup with cue ball impulse
10	Chaos	Many random bodies with random forces
11	Body Scaling	Bodies of varying sizes and masses
12	Collision Pit	Bodies funneled into a pit
13	Force Frenzy	Continuous forces applied to multiple bodies
14	Domino Cascade	Large-scale domino chain reaction
15	Overload	Stress test with maximum body count
19	Shape Gallery	All 10 shape types displayed side by side
20	Compound Constructions	Compound shapes built from child primitives
21	Mesh & Hull Playground	Convex hulls, triangle meshes, and shape references
22	Camera Showcase	Smooth camera transitions with narration overlay
23	Ball Rollercoaster	Heightmap mesh terrain with balls rolling along a track
24	Halfpipe Arena	Halfpipe terrain with bodies launched into the arena

Note: Demos 16–18 are reserved for future use. Demos 19–24 were added in later releases and use advanced shape types (compound, mesh, convex hull) and heightmap terrain.

Shared Prelude

Both language suites share a prelude library with 40+ helper functions:

F# Prelude (`Scripting/demos/Prelude.fsx`)

Key helpers:

// Session management
// let session = connect "https://localhost:7180"

// Body presets (marble, bowling ball, crate, etc.)
// let cmd = makeMarble "m-1" 0.0 5.0 0.0

// Batch commands (auto-splits at 100)
// batchAdd session commands

// Generators (stack, grid, pyramid, row)
// let cmds = makeStack "s" 5 0.0 0.0 0.0

// Simulation control
// resetSimulation session
// play session
// pause session

// Camera control with smooth transitions
// smoothCamera session (20.0, 15.0, 20.0) (0.0, 5.0, 0.0) 2.0

// Narration overlay
// narrate session "Demo Title" "Description text"

Python Prelude (`Scripting/demos_py/prelude.py`)

Mirrors the F# prelude with identical function names and behavior:

// # Session management
// channel, stub = connect("localhost:7180")
//
// # Body presets
// cmd = make_marble("m-1", 0.0, 5.0, 0.0)
//
// # Batch commands
// batch_add(stub, commands)
//
// # Generators
// cmds = make_stack("s", 5, 0.0, 0.0, 0.0)
//
// # Camera + narration
// smooth_camera(stub, (20, 15, 20), (0, 5, 0), 2.0)
// narrate(stub, "Demo Title", "Description")

Demo Structure

Each demo follows the same pattern:

Reset the simulation (clear all bodies, pause, reset time)
Create bodies using presets or generators
Configure gravity, camera, and other settings
Play the simulation
Apply forces, impulses, or other interactions
Wait for the demo duration
Pause and clean up

Example: Demo 01 — Hello Drop

// 1. Reset simulation
// resetSimulation session
//
// 2. Add a ground plane and a sphere at height 10
// let plane = makePlane "ground" 0.0 0.0 0.0
// let sphere = makeMarble "ball-1" 0.0 10.0 0.0
// batchAdd session [plane; sphere]
//
// 3. Set gravity and camera
// setGravity session 0.0 -9.81 0.0
// setCamera session (10.0, 5.0, 10.0) (0.0, 0.0, 0.0)
//
// 4. Play and watch
// play session
// sleep 5000

Next Steps

Getting Started — build and run the sandbox
MCP Tools — control demos via AI assistants
Architecture — understand the service design