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ReSkate/contrib/plugin-effects.md
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gbgyo 550887162f Effects: release stale resources and require resident assets
Resolve private effects only from the level-wide Game compartment and validate
their resident declarations with the same parser used by the mod merge.

Release surviving native services during world changes, check decal realm
ownership before cleanup, defer ordinary off-thread releases, and prune expired
VM handles so they return their quota. Size the temporary decal allowance from
the live count while preserving external settings changes.

Gate contact geometry behind events.physics.geometry, document the manifest
migration, and test Blood impacts through the plugin host using its own manifest.
Add regression coverage for residency, lifetime, quota and draw-budget handling.

Validation: Release builds of the runtime and plugin/effect test targets succeed.
The plugins, effect_geometry and effect_lifetime tests pass. Existing MSBuild
asset-directory dependency warnings remain; native visuals need an in-game check.
2026-10-26 22:19:43 +03:00

6.5 KiB
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Plugin particles and decals

The client reskate.effects API renders private mod assets. Declare the effects permission and list each allowed asset in the manifest's effects array (at most 128 names). Every name must also be covered by a valid resident root in the shared win32/levels/game/dingolevel_root/dingolevel_root bundle:

{
  "api": 1,
  "side": "client",
  "entry": "plugin/main.lua",
  "permissions": ["effects"],
  "effects": ["effects/reskate/example/ebp_spark", "world/materials/decal/reskate_example/stain_dv"],
  "resident": [{
    "bundle": "win32/levels/game/dingolevel_root/dingolevel_root",
    "roots": ["effects/reskate/example/", "world/materials/decal/reskate_example/"]
  }]
}

Particle names must start with effects/reskate/; decal names with world/materials/decal/reskate_. Names are lowercase letters, digits, slashes, underscores and hyphens, without empty path components. Stock/store asset names are refused. The native bridge also checks the loaded asset class: EffectBlueprint for particles and EnvironmentDecalVolumeTemplateData for decals. A declared name alone does not load content. Compile the effect assets and their dependencies into that shared root bundle. The native bridge only resolves effects in the level-wide Game compartment and checks the returned asset's own compartment before creating particles or decals. Assets in streamed sublevels are refused, even when a manifest claims that their names are resident; declaring a root does not load or pin its bundle. The global effect service must not retain references to streamed blueprint data.

The manifest's resident declarations preserve the roots and shaders when another mod replaces the shared bundle. Invalid declarations reject the plugin, including malformed shader entries that would make the merge discard the roots. For example:

"resident": [{
  "bundle": "win32/levels/game/dingolevel_root/dingolevel_root",
  "roots": ["effects/reskate/example/", "world/materials/decal/reskate_example/"],
  "shaders": [{
    "name": "world/materials/decal/reskate_example/shaderblockdepot_splash",
    "roots": ["world/materials/decal/reskate_example/"]
  }]
}]

Use the bundle and shader depot names produced when compiling your own assets. The effects allowlist contains exact names; resident.roots also accepts prefixes ending in /. These declarations reuse the normal mod merge; they do not create assets or compile shaders at runtime.

Calls

Call Result
particle(asset, transform) Opaque numeric handle, or nil, reason when unavailable or full
decal(asset, transform, {attach = false, lift = 0}) Handle, or nil, reason
move(handle, transform) Move a particle or an unattached decal
stop(handle) Stop particle emission while existing particles finish
opacity(handle, alpha) Set decal opacity, 0–1
release(handle) Stop and release one owned effect
clear() Release all this plugin's effects; safe to repeat
state() ready, epoch, describing the current native world

A transform is 16 numbers: three world-space basis vectors with a zero fourth component, then world position with a fourth component of one. The axes must be orthogonal and have length .001–20 metres; positions must be within ±100,000 metres. Particle emission points along its Y axis. Decal Y gives projection depth, X/Z its footprint. A decal with attach=true queries collision around its center, along Y; lift (0–1 metre) is the center's offset from the contact surface. A missed query returns nil. Bound decals follow the receiver's rigid pose and disappear when its generation-bearing physics handle becomes invalid.

Handles belong to one plugin and are never native addresses. Bad arguments, undeclared assets and foreign/released handles raise Lua errors. Each plugin can hold 24 particles and 2,048 decals and make 8,192 effect calls per tick. The native service caps all plugins together at 64 particles, 4,096 decals and 512 cached asset names. Native effects also expire after ten minutes of real time as a cleanup limit; plugins should release them sooner. Expired, detached and reset effects are pruned from the VM's handle table automatically and return their quota.

Decals add their current live count to the renderer's existing limits, reconciled at most once per second. Creation can therefore take up to a second to receive additional draw capacity. Clearing and recreating decals in a callback does not repeatedly resize render buffers. The allowance uses the in-memory SystemSettings service, separate from saved profile options; only its own changes are restored, and a later external settings edit is preserved.

Rendering is unavailable without a local skater, during loading, replay, Noclip or park editing, or when any required native byte check fails. Check state() before rendering and call clear() when its epoch changes, then discard local handles and simulation history. World resets automatically release native references. Expired handles become invalid once pruned; operations on them raise the same argument error as released handles. Unload, disable and VM failure release all effects. Effects are local and do not replicate. The dedicated server has no renderer: state() returns false and creation returns nil.

Physics geometry

events.physics keeps its existing timing/contact fields. Also declare events.physics.geometry to receive the following additions to physics_step:

  • state: optional local physics selector state.
  • bodies[name].point and .normal: optional world-space contact geometry. The normal accompanies the selected peak impact speed; unknown geometry is absent, not zero.
  • poses[name].transform and .velocity: optional world-space rigid body matrix (16 numbers) and linear velocity (three numbers, metres/second), including airborne bodies.

Plugins written before the geometry permission was introduced must add it to their manifest alongside events.physics. Without it, physics events still arrive but have no poses, contact points or normals, so effects that require those fields cannot detect impacts.

The host constructs the extra geometry JSON only while a plugin requests that permission and delivers it only to those plugins. These values are copied on the physics thread at the existing contact/skeleton boundary. Queued samples from another local entity/rig or a level transition are discarded. Missing fields mean unavailable data; do not synthesize a collision from them. The event's at is in the same milliseconds clock as reskate.time.now() and seconds is simulation time.