open-wc/docs/modules/m2-animated-instance-materializer.md

# M2 Animated Instance Materializer

## Metadata

| Field | Value |
|---|---|
| Status | Implemented extraction |
| Target/work package | M03 / `M03-RND-M2-ANIMATED-INSTANCE-MATERIALIZER-001` |
| Owners | Animated M2 duplicate/batch construction, render settings, playback startup and attachment |
| Last verified | Worktree `work/sindo-main-codex/m03-m2-animated-instance-materializer`, 2026-07-18 |
| Profiles/capabilities | Imported GLB and native experimental animated M2 instances |

## Purpose

Materialize one ordered animated M2 build batch on the main thread. The service
duplicates an accepted prototype, preserves historical names and transforms,
applies visibility/shadow settings recursively, starts native/imported playback,
attaches a non-empty batch and returns detached native diagnostic entries.

## Non-goals

- Plan build batches, advance job cursors or consume render budgets.
- Load, finalize, select or cache animated prototypes.
- Select animations or implement native animator deformation.
- Format logs, normalize paths, assign Editor owners or clean up tile roots.
- Materialize static M2 `MultiMesh` batches.

## Context and boundaries

```mermaid
flowchart LR
    Loader[StreamingWorldLoader adapter] --> Materializer[M2AnimatedInstanceMaterializer]
    Prototype[Accepted animated prototype] --> Materializer
    Plan[Transforms and batch slice] --> Materializer
    Materializer --> Playback[M2AnimationPlaybackController]
    Materializer --> Finalizer[M2AnimatedSceneFinalizer traversal]
    Materializer --> Batch[Attached animated batch]
    Materializer --> Diagnostics[Detached diagnostic entries]
```

Allowed dependencies are Godot Node/Node3D/GeometryInstance3D APIs and the
accepted animated finalizer and playback services. Resource loading, files,
workers, caches, scheduler policy, Editor ownership and `MultiMesh` are forbidden.

## Public API

| Symbol | Kind | Purpose | Thread/lifetime | Errors |
|---|---|---|---|---|
| `materialize_batch(parent, path, prototype, transforms, start, count, serial, visibility_end, visibility_margin, cast_shadows, native_script, collect_diagnostics)` | Command/query | Build, start and attach one ordered animated batch | Main thread; borrowed inputs, parent owns result | Invalid/empty input or all failed duplicates returns `{}` |

## Inputs and outputs

| Direction | Contract/data | Producer | Consumer | Ownership | Thread/lifetime |
|---|---|---|---|---|---|
| Input | M2 parent root | Loader build job | Batch attachment | Borrowed Node3D | Tile/job lifetime |
| Input | Relative path, start/count and serial | Batch planner/loader adapter | Names, phase and slice | Copied scalars | One call |
| Input | Accepted animated prototype | Prototype cache | Duplicate source | Borrowed Node3D | Cache-owned |
| Input | Ordered transforms | Placement grouping/build job | Instance transforms | Borrowed Array | Job lifetime |
| Input | Visibility/shadow settings | Renderer configuration | Recursive render mutation | Copied scalars | One call |
| Input | Native animator Script identity | Loader composition | Playback controller | Borrowed Script | Application lifetime |
| Output | `batch_root` | Materializer | Parent SceneTree and loader Editor-owner adapter | Parent-owned Node3D | Tile lifetime |
| Output | `native_diagnostics` entries | Playback controller/materializer | Loader log adapter | Caller-owned Array/Dictionaries | Debug call |

Side effects are Node duplication, instance naming/transform assignment,
recursive geometry mutation, playback mutation and SceneTree attachment. The
service retains no batch, prototype, transform or diagnostic references.

## Data flow

```mermaid
flowchart TD
    Slice[Ordered transform slice] --> Duplicate[Duplicate prototype with signals, groups and scripts]
    Duplicate --> Identity[Assign historical name and transform]
    Identity --> Render[Apply visibility margin and shadow recursively]
    Render --> NativeCopy[Copy native animator runtime fields]
    NativeCopy --> AttachInstance[Attach duplicate to detached batch]
    AttachInstance --> Players[Inventory AnimationPlayers]
    Players --> Start[Start deterministic native/imported playback]
    Start --> More{More slice entries?}
    More -->|yes| Duplicate
    More -->|no, non-empty| AttachBatch[Attach batch to supplied parent]
    Start --> Diagnostics[Tag detached states with instance index]
```

## Lifecycle/state

```mermaid
stateDiagram-v2
    [*] --> Validating
    Validating --> Empty: invalid input
    Validating --> Building: valid slice
    Building --> Building: next successful duplicate
    Building --> Empty: no successful duplicates
    Building --> Attached: non-empty batch
    Empty --> [*]
    Attached --> [*]: parent/tile owner releases subtree
```

The `RefCounted` service is stateless; lifecycle labels describe each batch call.

## Main sequence

```mermaid
sequenceDiagram
    participant L as StreamingWorldLoader
    participant M as M2AnimatedInstanceMaterializer
    participant F as M2AnimatedSceneFinalizer
    participant P as M2AnimationPlaybackController
    participant R as M2 parent root
    L->>M: materialize_batch(slice, prototype, render settings)
    loop ordered instance
        M->>M: duplicate, name, transform, render settings
        M->>P: copy native animator fields
        M->>F: animation_players_in_subtree(duplicate)
        M->>P: start_instance_playback(path, index, players, debug)
    end
    M->>R: add_child(non-empty batch)
    M-->>L: batch root and indexed diagnostics
    L->>L: format logs and assign Editor owner
```

## Dependency diagram

```mermaid
flowchart TB
    Loader[StreamingWorldLoader] --> Materializer[M2AnimatedInstanceMaterializer]
    Materializer --> Playback[M2AnimationPlaybackController]
    Materializer --> Finalizer[M2AnimatedSceneFinalizer]
    Materializer --> Engine[Node3D / GeometryInstance3D / SceneTree APIs]
    Loader --> EditorOwner[Editor ownership adapter]
    Loader --> BuildJob[Build cursor and budget]
    Materializer -. no dependency .-> Cache[Prototype/cache/load state]
    Materializer -. no dependency .-> MultiMesh[Static M2 materialization]
```

## Ownership, threading and resources

- Loader/build state borrows the accepted prototype and ordered transform Array.
- Each successful duplicate becomes a child of the detached batch immediately.
- A non-empty batch transfers to the supplied parent; the parent owns its lifetime.
- A batch with no successful duplicates is queued for deletion and no reference returns.
- Playback/finalizer services borrow each duplicate only during synchronous calls.
- Returned diagnostic entries contain the stable instance index and a detached state.
- All Node duplication, mutation and attachment is main-thread-only.

## Errors, cancellation and recovery

| Failure | Detection | Behavior | Diagnostic | Recovery |
|---|---|---|---|---|
| Null parent/prototype | Entry guard | Return `{}` without mutation | Contract verifier | Correct composition/cache state |
| Empty transforms or non-positive count | Entry guard | Return `{}` | Contract verifier | Planner supplies a non-empty slice |
| Duplicate is not Node3D | Cast result | Skip that entry and preserve order of successes | Child-count contract | Repair prototype scene root |
| Every duplicate fails | Empty batch check | Queue empty batch, return `{}` | Empty-result contract | Rebuild/import prototype |
| Shutdown during/after call | Outside service | Call is synchronous; loader owns cancellation and subtree release | Shutdown regression | Loader cancels job/releases parent |

Transform bounds remain a planner/build-job precondition exactly as before the
extraction; this service does not clamp or silently reorder an invalid slice.

## Configuration and capabilities

| Setting/capability | Default | Profile | Runtime mutable | Effect |
|---|---|---|---|---|
| Duplicate flags | Signals + groups + scripts | All | No | Preserves historical instance behavior |
| Visibility end/margin | Loader renderer settings / chunk size | All | Yes, between calls | Applied to every GeometryInstance3D descendant |
| Shadow mode | Loader `m2_cast_shadows` | All | Yes, between calls | Enables/disables descendant shadow casting |
| Native diagnostics | Loader `debug_streaming` | Debug | Yes | Collects indexed state only when requested |

## Persistence, cache and migration

No data is serialized and no cache/schema version changes. Editor owner
assignment remains a loader concern after attachment, so generated-scene
persistence behavior and migration remain unchanged.

## Diagnostics and observability

- The materializer emits no logs, metrics or debug views.
- Native state remains detached and is tagged with the absolute instance index.
- Loader preserves the existing normalized-path `M2_NATIVE_ANIMATOR` log text.
- No correlation ID is introduced; path/index remains the existing identity.

## Verification

- `verify_m2_animated_instance_materializer.gd` covers invalid input, names,
  order, transforms, recursive visibility/margin/shadows, playback, native field
  references, indexed diagnostics, prototype immutability and ownership boundaries.
- Playback/finalizer/pipeline/build/prototype/shutdown/material/facade/internal-
  access regressions protect adjacent behavior.
- Fidelity evidence is exact extraction of existing flags/order/settings/calls;
  no original-client visual comparison or proprietary asset result is claimed.
- Performance budget: 1,000 synthetic Node3D instances under one second.

## Extension points

A later facade-owned animated presentation command may supply the same explicit
batch contract. Async SceneTree mutation, callbacks and a generic scene factory
are intentionally excluded until measurements show a need.

## Capability status

| Capability | Status | Evidence | Gap/next step |
|---|---|---|---|
| Ordered animated instance/batch materialization | Implemented extraction | Synthetic batch contract verifier | Proprietary asset traversal pending |
| Recursive visibility/shadow settings | Implemented extraction | Nested geometry fixture | Visual distance/shadow comparison pending |
| Native/imported playback startup | Delegated to implemented controller | Playback + materializer verifiers | Full WoW animation-state mapping pending |
| Editor persistence | Existing loader-owned | Source boundary and editor helper | Editor integration fixture remains separate |

## Known gaps and risks

- The existing build planner must continue to guarantee valid transform bounds.
- Default animation selection and native deformation retain their documented gaps.
- No private asset, paired original-client, descriptor-pressure, leak or p95/p99 run exists.
- Recursive render mutation remains proportional to duplicate subtree size.

## Source map

| Path | Responsibility |
|---|---|
| `src/render/m2/m2_animated_instance_materializer.gd` | Duplicate, render mutation, playback startup and non-empty batch attachment |
| `src/render/m2/m2_animation_playback_controller.gd` | Phase, selection and native/imported playback mutation |
| `src/render/m2/m2_animated_scene_finalizer.gd` | AnimationPlayer inventory for each duplicate |
| `src/scenes/streaming/streaming_world_loader.gd` | Build adapter, diagnostic formatting and Editor ownership |
| `src/tools/verify_m2_animated_instance_materializer.gd` | Batch/render/playback/boundary/timing regression |

## Related decisions and references

- [`m2-animation-playback-controller.md`](m2-animation-playback-controller.md)
- [`m2-animated-scene-finalizer.md`](m2-animated-scene-finalizer.md)
- [`m2-build-batch-planner.md`](m2-build-batch-planner.md)
- [`world-renderer.md`](world-renderer.md)
- [`../../RENDER.md`](../../RENDER.md)
- [`../../targets/roadmap/02-rendering-and-graphics.md`](../../targets/roadmap/02-rendering-and-graphics.md)