823936ec31
Detach old-world spatial ownership atomically, prioritize destination retirement dependencies, and reveal the viewport at the retail transition edge. Give private paperdoll views independent mesh ownership and retain dormant ACE entities so portal revisits preserve server objects without extending active GPU lifetimes.
178 lines
8 KiB
Markdown
178 lines
8 KiB
Markdown
# Retail object liveness and modern mesh reclamation
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## Symptom and measured cause
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After several distant portal transitions, acdream could fall from normal
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frame rates to 3–12 FPS and remain there. Lightweight ownership counters
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showed that each destination left its server objects in `LiveEntityRuntime`:
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the live-record count, animated-owner count, particle/effect ownership, and
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materialized render owners grew monotonically. The render thread eventually
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blocked in the native GL driver even though the current destination submitted
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only a small number of visible particles.
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The modern shared mesh buffers had a second cumulative ownership defect. The
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old `GlobalMeshBuffer.Append` copied the complete vertex array once for every
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material batch and only advanced append offsets. `ObjectMeshManager` eviction
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removed cache entries and textures but could not return those vertex/index
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ranges. This was not the first-frame collapse mechanism, but it guaranteed
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that portal and cache churn permanently consumed GPU address space.
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## Named-retail oracle
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The retail client owns one object table and separates leaving visibility from
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logical destruction:
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- `CPhysicsObj::prepare_to_leave_visibility` (`0x00511F40`) removes shadows,
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leaves the cell, and calls `CObjectMaint::AddObjectToBeDestroyed` for the
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object and each child.
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- `CObjectMaint::AddObjectToBeDestroyed` (`0x00508F70`) replaces any existing
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deadline with `Timer::cur_time + 25.0`, then inserts the GUID in the ordered
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destruction queue.
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- `CPhysicsObj::prepare_to_enter_world` (`0x00511FA0`) cancels the queued
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destruction for the object and its children before re-entry.
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- `CObjectMaint::UseTime` (`0x005089B0`) rebuilds the visible-object table at
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one-second intervals and drains every due destruction entry in time order.
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- `CObjectMaint::DeleteObject` (`0x00508460`) performs symmetric teardown:
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exit/leave world, remove object/null-object table ownership, remove the
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destruction entry, unparent, unparent children, then destroy the object.
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- `SmartBox::Reset` (`0x00453BF0`) destroys the complete object table only for
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a true session/reset path. A portal is not a session reset.
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The 25-second mechanism is exact retail behavior. The client decides that an
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object left visibility from ObjCell/PVS membership, not from a raw distance
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constant.
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## ACE compatibility boundary
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ACE retains a player's `KnownObjects` across normal teleports. Its optional
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`teleport_visibility_fix` is disabled by default and is explicitly described
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as a non-retail automated workaround. Therefore a client cannot depend on an
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F747 `DeleteObject` when an old destination leaves visibility.
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Holtburger independently implements the client half with the exact retail
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25-second timeout and a conservative 384-world-unit distance envelope while
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exact ACE ObjCell visibility is unavailable. It also treats scene-nearby
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objects as visible and retains held, equipped, container, wielder, parent, and
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preview-owned objects. Sources:
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- [ACE ObjectMaint](https://github.com/ACEmulator/ACE/blob/650c5b75ae909957feaf58db320e46be16502653/Source/ACE.Server/Physics/Common/ObjectMaint.cs)
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- [ACE Player teleport tracking](https://github.com/ACEmulator/ACE/blob/650c5b75ae909957feaf58db320e46be16502653/Source/ACE.Server/WorldObjects/Player_Tracking.cs)
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- [Holtburger liveness](https://github.com/merklejerk/holtburger/blob/main/crates/holtburger-world/src/state/liveness.rs)
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acdream uses the same visibility boundary: currently spatially resident
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records are visible; otherwise a 384-unit 3-D global-landblock distance is the
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conservative fallback. The distance is an adaptation, not a claimed retail
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constant, and remains documented in divergence AP-69 until exact ObjCell/PVS
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membership drives the deadline.
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There is an additional ACE compatibility boundary. Retail can destroy the
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complete client object because its server/client visibility protocol later
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recreates that object. ACE may retain the GUID in `KnownObjects` across a
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normal teleport and consequently omit the later `CreateObject`. Deleting
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acdream's only accepted `EntitySpawn` at the 25-second deadline therefore
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made doors, signs, portals, NPCs, and other server objects permanently absent
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when a destination was revisited.
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The modern client separates those two costs:
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- the 25-second deadline destroys every active projection, collision,
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animation, physics, script, light, particle, and render owner;
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- a cold `EntitySpawn` snapshot remains in a data-only dormant table;
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- reloading its authoritative landblock routes that snapshot through the
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ordinary generation-safe CreateObject hydration transaction;
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- an explicit F747, a newer INSTANCE timestamp, or session reset removes the
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dormant snapshot.
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This is deliberately not active-object retention: dormant entries execute no
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per-frame work and own no GPU resources. It restores the former retained
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spawn-table contract required by ACE while preserving the resource reclamation
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that fixed the portal-run FPS collapse.
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## Port pseudocode
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```text
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once per second:
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if player has no authoritative world position:
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do nothing
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for each live record with a world position except the player:
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retained = record is attached
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OR has container owner
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OR has wielder owner
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OR has physics parent
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visible = record has a resident spatial projection
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OR global_3d_distance(player, record) <= 384
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if visible OR retained:
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cancel record deadline
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else if no deadline exists for this GUID + generation:
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deadline = now + 25 seconds
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else if deadline <= now:
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emit (GUID, generation) prune candidate
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discard deadlines for records no longer in the canonical table
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for each due candidate:
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re-read canonical record
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if GUID and generation still match:
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capture its latest accepted EntitySpawn
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run the normal generation-safe active teardown
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retain only the cold EntitySpawn
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when a landblock becomes resident:
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for each dormant spawn in that canonical landblock:
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route it through ordinary CreateObject hydration
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remove the dormant entry only after the generation is accepted
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on explicit DeleteObject:
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delete the exact active or dormant generation
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remove its ClientObject qualities
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on session reset:
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clear active runtime and dormant snapshots
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```
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Routing expiry through `LiveEntityRuntime.UnregisterLiveEntity` is important:
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it performs the same generation gate, equipped-child cleanup, spatial
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withdrawal, animation/physics/effect teardown, and render resource release as
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an authoritative F747. Unlike F747, local visibility expiry preserves the
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small object-quality record and cold spawn because ACE may never resend them.
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An actual F747 removes both. A second active-resource teardown path would
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drift and recreate the original leak.
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## Reclaimable shared-buffer contract
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```text
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upload one mesh:
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collect non-empty material index batches in authored order
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allocate one contiguous vertex range
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allocate one contiguous index range
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upload vertices exactly once
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append each index batch inside that index range
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record each batch's first-index and the shared base-vertex
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evict one zero-reference mesh:
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release its index range
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release its vertex range
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coalesce adjacent free ranges
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release atlas texture ownership
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if no contiguous range fits:
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grow the GL buffer
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copy through the allocator high-water mark
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extend/coalesce the trailing free range
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allocate again
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```
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The range allocator uses best fit to preserve larger holes, rejects overlap or
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double release before changing accounting, and keeps buffer resizing on the
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existing update/render thread.
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## Connected verification
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A Release client was driven through C95B → 3032 → F682 → 0905 → 0904 → C95B.
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Old-region deadlines expired after 25 seconds; live and animation-owner counts
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fell instead of accumulating. Released mesh ranges became reusable. Returning
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to C95B rebuilt its objects correctly, and the location remained at its normal
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roughly 60–80 FPS instead of the prior persistent 3–12 FPS state.
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