open-wc/docs/modules/coordinate-mapping.md

Coordinate Mapping

Metadata

Field	Value
Status	Implemented
Target/work package	M01-FND-COORDS-001
Owners	Foundation/domain
Last verified	Worktree work/sindo-main-codex/m01-coordinate-mapper, 2026-07-13
Profiles/capabilities	All profiles; contract version 1

Purpose

Provide scene-free value objects and one pure CoordinateMapper for positions, ADT grid ownership and world-facing yaw. The module makes every source space explicit before renderer, network, gameplay and authoring consumers migrate.

Non-goals

• Reading ADT, packet, SQL or scene data.
• Constructing Vector3, Transform3D, Node or Resource values.
• Correcting M2/WMO local axes or MDDF/MODF Euler rotations.
• Selecting maps, validating terrain height or owning streaming focus.
• Persisting coordinate values in this work package.

Context and boundaries

flowchart LR
    Server[Server / movement X,Y,Z] --> ServerPosition[ServerWorldPosition]
    ADT[MDDF/MODF X,height,Z] --> AdtPosition[AdtPlacementPosition]
    ServerPosition --> Mapper[CoordinateMapper]
    AdtPosition --> Mapper
    Mapper --> Canonical[CanonicalWowWorldPosition]
    Canonical --> Tile[AdtTileCoordinate + AdtTileLocalPosition]
    Canonical --> GodotPosition[GodotWorldPosition]
    GodotPosition --> Adapter[Future scene/render adapter]
    Adapter --> Vector[Vector3 at boundary]
    Scene[Node / Camera3D / scene lookup] -. forbidden .-> Mapper

Allowed dependencies:

• GDScript scalar math and RefCounted lifetime;
• other value objects in src/domain/coordinates;
• callers in network, gameplay, render and server-data adapters.

Forbidden dependencies:

• Node, Resource, SceneTree, Camera3D and global scene lookup;
• packet buffers, SQL rows, asset parsers and renderer state;
• Vector3 as a public mapper input or output;
• model-specific placement corrections.

Public API

Symbol	Kind	Purpose	Thread/lifetime	Errors
CanonicalWowWorldPosition	Immutable value	Client/server X/Y/Z in yards	Any thread; caller-owned reference	No bounds validation
ServerWorldPosition	Immutable value	Server/wire X/Y/Z in yards	Any thread; caller-owned reference	No adapter validation
AdtPlacementPosition	Immutable value	MDDF/MODF X/height/Z fields	Any thread; caller-owned reference	No file validation
GodotWorldPosition	Immutable value	Godot east/up/south scalars	Any thread; caller-owned reference	Does not create Vector3
AdtTileCoordinate	Immutable value	Map_tileX_tileY.adt indices	Any thread; caller-owned reference	is_within_map_grid() reports invalid indices
AdtTileLocalPosition	Immutable value	East/height/south offsets from tile north-west corner	Any thread; caller-owned reference	Values are intentionally unclamped
AdtChunkCoordinate	Immutable value	MCNK chunk indices inside one tile	Any thread; caller-owned reference	is_within_map_grid() reports invalid indices
CanonicalWowWorldYaw	Immutable value	Canonical world yaw in radians	Any thread; caller-owned reference	Constructor does not normalize
ServerWorldYaw	Immutable value	Movement orientation in radians	Any thread; caller-owned reference	Constructor does not normalize
GodotWorldYaw	Immutable value	Godot Y-axis world yaw in radians	Any thread; caller-owned reference	Constructor does not normalize
CoordinateMapper.server_to_canonical / inverse	Pure static methods	Preserve server X/Y/Z as canonical	Synchronous; new result value	Null input is a caller contract violation
CoordinateMapper.canonical_to_godot / inverse	Pure static methods	Apply Y-up renderer basis and map offset	Synchronous; new result value	Non-finite scalars propagate
CoordinateMapper.canonical_to_adt_placement / inverse	Pure static methods	Convert ADT placement field basis	Synchronous; new result value	Non-finite scalars propagate
CoordinateMapper.canonical_to_adt_tile	Pure static method	Compute unclamped filename indices	Synchronous; new result value	Out-of-map result remains invalid
CoordinateMapper.canonical_to_adt_tile_local / inverse	Pure static methods	Split/reconstruct tile-local position	Synchronous; new result value	Caller validates tile ownership
CoordinateMapper.adt_tile_local_to_chunk	Pure static method	Compute unclamped MCNK indices	Synchronous; new result value	Boundary/out-of-range remains diagnosable
World-yaw mapper methods	Pure static methods	Normalize and cross the world-basis boundary	Synchronous; new result value	Non-finite input is unsupported

Inputs and outputs

Direction	Contract/data	Producer	Consumer	Ownership	Thread/lifetime
Input	ServerWorldPosition, ServerWorldYaw	Future protocol/server adapter	CoordinateMapper	Immutable caller value	Any thread, call duration
Input	AdtPlacementPosition	Future ADT adapter	CoordinateMapper	Immutable caller value	Any thread, call duration
Input	CanonicalWowWorldPosition, CanonicalWowWorldYaw	Gameplay/content/domain	CoordinateMapper	Immutable caller value	Any thread, call duration
Output	CanonicalWowWorldPosition	CoordinateMapper	Gameplay/content/adapters	New immutable value	Caller-owned reference
Output	AdtTileCoordinate, AdtTileLocalPosition, AdtChunkCoordinate	CoordinateMapper	Streaming/content adapters	New immutable values	Caller-owned references
Output	GodotWorldPosition, GodotWorldYaw	CoordinateMapper	Future render/scene adapter	New immutable values	Caller-owned references

Side effects:

• none;
• no scene mutation, file/cache write, network send, database access or logging.

Data flow

flowchart LR
    Server[ServerWorldPosition X,Y,Z] -->|identity components| Canonical[CanonicalWowWorldPosition]
    ADT[AdtPlacementPosition X,height,Z] -->|half extent - horizontal| Canonical
    Canonical -->|floor 32 - axis / tile size| Tile[AdtTileCoordinate]
    Canonical -->|north-west edge offsets| Local[AdtTileLocalPosition]
    Local -->|floor offset / chunk size| Chunk[AdtChunkCoordinate]
    Canonical -->|half extent - Y; Z; half extent - X| Godot[GodotWorldPosition]
    ServerYaw[ServerWorldYaw] -->|normalize only| CanonicalYaw[CanonicalWowWorldYaw]
    CanonicalYaw -->|same numeric world angle| GodotYaw[GodotWorldYaw]

Lifecycle/state

The module is stateless. Each call reads immutable scalar inputs and returns a new value object. There is no initialization, shutdown, cancellation or retry state machine.

Main sequence

No cross-layer asynchronous sequence occurs inside this module. Producers parse or validate their external format first, call the mapper synchronously, and then pass only typed results across the next boundary.

Ownership, threading and resources

• Value objects own only scalar fields and, for chunks, one immutable tile reference.
• Callers own returned RefCounted references.
• Methods do not mutate inputs or shared state and are safe for worker use.
• No Node, RID, file, socket, database or cache resource is acquired.

Errors, cancellation and recovery

Failure	Detection	Behavior	Diagnostic	Recovery
Tile/chunk outside standard grid	is_within_map_grid()	Unclamped indices are preserved	Caller reports source and map context	Reject or apply explicit map policy
Tile-local value outside half-open tile	Consumer boundary validation	Value is preserved	Caller reports source coordinate	Recompute ownership or reject malformed input
Null value object	Static typing/call failure	Programming contract violation	GDScript error with call site	Fix producer; no fallback value
NaN/infinite scalar	Adapter validation	Arithmetic propagates invalid value	Adapter must report source field	Reject malformed external input

There is no cancellation because every conversion is constant-time scalar math.

Configuration and capabilities

Setting/capability	Default	Profile	Runtime mutable	Effect
Contract version	1	All	No	Axis, unit and boundary semantics in ADR 0001
Godot units per WoW yard	1	Blizzlike335 and current tools	No	Preserves current renderer scale
ADT grid	64 tiles/axis, 16 chunks/tile	WotLK 3.3.5a	No	Defines index and boundary math

Persistence, cache and migration

This package adds no persisted format, cache or migration. Existing dictionaries, native Vector3 payloads and renderer conversion helpers remain compatible. Consumer migration is ordered after this contract and must remove old manual conversions only after its producer/consumer tests pass.

Any future serialized coordinate must store a schema version and explicit space; raw three-number arrays are not an accepted new persistence contract.

Diagnostics and observability

• Logs: none in production mapper.
• Metrics: none; conversion cost is constant and outside frame-budget concern.
• Debug views: headless contract probe prints one PASS summary.
• Correlation IDs: supplied by external adapters if an invalid source is reported.

Verification

• Unit/contract tests: src/tools/verify_coordinate_mapper.gd.
• Integration/E2E: consumer migration and StreamingFocus packages remain pending.
• Fidelity evidence: five build-12340 camera positions from the M00 manifest map within 0.002 yard; independent reference formulas are recorded in ADR 0001.
• Performance budgets: constant-time arithmetic; no scene or file access.
• Manual diagnostics: not required for the pure contract; renderer checkpoints are required when consumers migrate.

Extension points

• Add typed map IDs around positions without changing axis semantics.
• Add a format-specific placement-orientation adapter with its own fixtures.
• Add serialization only with explicit space/version fields and migrations.
• Add consumer adapters that construct engine-native vectors at their boundary.

Capability status

Capability	Status	Evidence	Gap/next step
Canonical/server/Godot position mapping	Implemented	Headless round-trip and five M00 golden points	Migrate producers/consumers
ADT placement mapping	Implemented	Synthetic/direct round-trip fixtures	Compare native parsed placements during migration
ADT tile/local/chunk ownership	Implemented	Center, extent, tile and chunk boundary fixtures	Migrate streaming names/ownership
World-facing yaw mapping	Implemented	Cardinal/wrap round-trip fixtures	Placement Euler remains separate
Scene-free production contract	Implemented	Source boundary and headless test	Add dependency search gate later in M01
Visual/server-spawn integration	Planned	M01 target criteria	Add golden server spawn after adapter migration

Known gaps and risks

• Existing native loaders and renderer scripts still contain manual conversions.
• Current StreamingWorldLoader tile names may represent Godot X/Z ordering rather than ADT filename X/Y; migration must preserve visible baseline behavior.
• MDDF/MODF rotation comments and implementations disagree across existing paths; this package deliberately does not generalize them into world yaw.
• Finite-number validation belongs to external format adapters and is not yet implemented.
• Arithmetic agreement does not prove terrain, placement, camera direction or visual parity.

Source map

Path	Responsibility
src/domain/coordinates/coordinate_mapper.gd	Constants and all coordinate-axis conversions
src/domain/coordinates/*_position.gd	Immutable typed position values
src/domain/coordinates/adt_tile_coordinate.gd	ADT filename tile indices and bounds
src/domain/coordinates/adt_chunk_coordinate.gd	MCNK indices and bounds
src/domain/coordinates/*_yaw.gd	Immutable typed world-facing yaw values
src/tools/verify_coordinate_mapper.gd	Headless fixtures and boundary regressions
docs/adr/0001-canonical-world-coordinates.md	Normative axes, units, boundaries and rollout decision

Related decisions and references

• ADR: ../adr/0001-canonical-world-coordinates.md
• M00 evidence: ../M00_FINAL_PAIRED_EVIDENCE.md
• Architecture: ../ARCHITECTURE.md
• Testing rules: ../TESTING.md