WaterZoneSystem

Remarks

[35 § D3](../../docs/plan/35-water.md#d3-the-water-info-texture-is-the-interchange-and-it-is-a-zone-render)'s zone, wired to a scene. Every WaterBodyComponent is claimed by whichever zones' windows reach it, and each zone re-rasterises only when it has to.

⚠ A body with no zone renders nothing, and the count is what says so. That is Unreal's rule — AWaterZone must exist or nothing renders — kept because the field is the interchange every consumer reads. What is not kept is discovering it from a blank frame: ZonelessBodies is a number an author can look at, and it is the answer to "I placed a lake and there is no water".

⚠ Bodies are cached by identity, and that is what makes the whole amortisation real. A fold that built a fresh WaterBody every frame would hand the zone a different list every frame, mark the field dirty every frame, and re-rasterise every frame — which is the cost § D3's threshold exists to avoid, paid in full and invisibly. So a body is rebuilt only when its component or its transform actually changed, and the zone compares by reference.

In PreRender, after TransformSystem has written WorldTransform, so a body that moved this frame is rasterised where it now is rather than where it was.

Fields and properties (14)

• public RenderView View

  The view this centres its windows on.

• public IWaterSplineSource? Splines

  Where a body's curve comes from.

• public IWaterWaveSource? Waves

  Where a zone's sea state comes from, for the zones that name a .vxwaves.

• public IWaterGround Ground

  Where the ground under the water is.

• public int ZoneCount

  How many zones the last fold saw.

• public int BodyCount

  How many bodies resolved to a curve.

• public int ZonelessBodies

  How many bodies no zone's window reached.

• public int UnresolvedBodies

  How many bodies named a spline nothing could supply.

• public int UnresolvedWaves

  How many zones named a .vxwaves that could not be used.

• public int RebuiltBodies

  How many bodies were rebuilt by the last fold.

• public SystemAccess Access
• public IReadOnlyDictionary<Entity, WaterZoneState> States

  The state of a zone, by the entity carrying it.

• public IReadOnlyList<(Entity Entity, WaterZoneComponent Component)> Zones

  What each zone entity said, as the last fold read it — with its names resolved.

• public float WaterTime

  The simulation's water time, in seconds — the one clock the whole stack reads.

Methods (5)

• public WaterZoneSystem(RenderView view)

  Folds a world's zones and bodies into the fields everything else reads.

• public WaterQuery? QueryAt(Vector2 position)
• public IPostProcessShape? ShapeFor(Entity entity)
• public override JobHandle Update(in SystemContext context, JobHandle dependency)
• public void Fold(World world)

  Gathers this frame's zones and bodies and brings every field up to date.

Used by (13)

• AppGraphicsVixen.App.Hosting
• UnderwaterPassTestsVixen.Rendering.Water.Tests
• UnderwaterRendererVixen.Rendering.Water
• WaterClockSystemVixen.Rendering.Water
• WaterDebugDrawVixen.Rendering.Water
• WaterDebugDrawTestsVixen.Rendering.Water.Tests
• WaterHorizonImageTestsVixen.Graphics.Golden.Tests
• WaterMeshRendererVixen.Rendering.Water
• WaterOverlayVixen.Rendering.Water
• WaterRendererFactoryVixen.Rendering.Water
• WaterZoneSystemTestsVixen.Rendering.Water.Tests
• WaterPresenterVixen.Editor.App
• WaterSceneRunsTestsVixen.Editor.Assets.Tests