ArtillerySimulator — 10× scale-down + bounds safety

name: ArtillerySimulator scale fix overview: Scale the ArtillerySimulator world down 10× so ballistic ranges fit inside terrain, and add heightfield/bounds fallbacks so shots never run forever past the mesh. todos:

• id: sim-units

content: Add SimulationUnits.cs with 10× scaled extent, speeds, camera, hill amplitudes status: completed

• id: terrain-gun-cam

content: Wire TerrainWorld, GunModel, ArtilleryCamera to SimulationUnits status: completed

• id: bounds-contact

content: "ProjectileRun: TerrainWorld heightfield + OOB termination; reduce MaxSteps" status: completed

• id: preview-hud

content: BallisticArcPreview bounds stop; HUD beyond-range label status: completed

• id: build-verify

content: Release build + manual fire check (impact within 50 m) status: completed isProject: false

Problem

Your screenshot (Alt -25871 m, T 147 s, InFlight) is a range mismatch, not a sweep bug:

flowchart LR
  gun[Gun at x=40] --> fire[Fire 600 m/s]
  fire --> leaves[Leaves 500m mesh in ~1s]
  leaves --> fall[No collision Y to -inf]

You chose scale down 10× (not 5 km expansion).

Approach: single `SimulationUnits` + proportional retune

Add `Game/SimulationUnits.cs` as the one place for world scale (easy to tune later):

Keep collision 64×64 and draw 32×32 on 50 m → ~0.78 m / ~1.6 m quads (good for sweeps). No mesh density change needed.

Gun visuals: keep `BarrelLength` ~5.2 m so the piece stays visible on a 50 m map (~10% of width); only world placement and speeds scale.

Files to update

1. [`SimulationUnits.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\SimulationUnits.cs) (new)

Central constants: ExtentMeters, GunPivotX, GunHeightOffset, charge speed array, camera offsets, height amplitude scalars.

2. [`TerrainWorld.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\TerrainWorld.cs)

• Replace ExtentMeters = 500f with SimulationUnits.ExtentMeters.
• Gun baseline: (GunPivotX, SampleHeight(...), Extent * 0.5f).
• Scale SampleHeight base amplitudes via SimulationUnits.

3. [`GunModel.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\GunModel.cs)

• Charge speeds from SimulationUnits.ChargeSpeedsMps.

4. [`ArtilleryCamera.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\ArtilleryCamera.cs)

• Fixed/chase offsets from SimulationUnits.

5. [`ProjectileRun.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\ProjectileRun.cs) — **bounds safety** (required even after scale)

After each accepted integration step (and on sub-steps), call TerrainWorld helpers:

• IsInside(x, z) → x,z ∈ [0, Extent] with small margin.
• TryHeightfieldContact(position, radius) → Y <= SampleHeight(x,z) + radius when inside (catches mesh edge misses).

If outside bounds or below heightfield: RecordImpact and set phase Impacted (optional ImpactResult flag or HUD text "Beyond range" when OOB vs mesh hit).

Pass TerrainWorld into AdvanceWithBudget instead of only BvhStaticWorld so heightfield checks are available.

Reduce MaxSteps proportionally (e.g. 12_000 ≈ 100 s cap at 1/120 s — enough for 50 m world).

6. [`BallisticArcPreview.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\BallisticArcPreview.cs)

• Stop preview when !terrain.IsInside(p.X, p.Z) (not only height sample).
• MaxTimeSeconds can stay 12 s (plenty at 80 m/s).

7. [`SimulationHud.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\SimulationHud.cs)

• Show Beyond range when impact was OOB (if we add a bool on ImpactResult or ShotEndReason enum).

8. [`ArtillerySimulatorGame.cs`](d:\novolis\novolis-dogfooding\apps\ArtillerySimulator\Game\ArtillerySimulatorGame.cs)

• Wire AdvanceWithBudget(_terrain, ...) signature change only.

Expected outcome

• Charge 2 @ 45° over hills: lands inside 50 m patch within a few seconds; HUD shows impact range < ~50 m, altitude sane.
• Flat + vacuum sanity log still valid (2*vx*vy/g with new speeds).
• No more multi-minute InFlight with huge negative altitude.

Validation

1. dotnet build Release on ArtillerySimulator.
2. Manual: fire all three charges at 45° — each should Impacted with range on HUD < 50 m.
3. Fire at max elevation toward edge — should end as Beyond range or terrain hit, not infinite fall.

No edits to the polish plan file or physics libraries.