@dcl/ecs
Version:
Decentraland ECS
201 lines (200 loc) • 10.8 kB
JavaScript
import * as components from '../components';
import { EntityState } from '../engine/entity';
/**
* Builds a synthetic PBTriggerAreaResult for a per-tick onStay callback.
*
* Transform components are resolved at call time so that scene-owned entities report
* up-to-date position/rotation/scale. For player-avatar triggerers (reserved entities
* without a scene-side Transform), there is no scene Transform component, so the cached
* values from the last ENTER or wire-STAY event are used as-is. These cached values may
* be slightly stale for the current frame — this is expected and acceptable for the
* avatar case.
*/
function buildSyntheticStayResult(cached, triggerAreaEntity, triggererEntity, currentTimestamp, Transform) {
// Shallow-clone the trigger sub-object so we can mutate it.
const trigger = cached.trigger
? {
entity: cached.trigger.entity,
layers: cached.trigger.layers,
position: cached.trigger.position ? { ...cached.trigger.position } : undefined,
rotation: cached.trigger.rotation ? { ...cached.trigger.rotation } : undefined,
scale: cached.trigger.scale ? { ...cached.trigger.scale } : undefined
}
: undefined;
// Build the cloned result with a forced TAET_STAY eventType and refreshed timestamp.
const result = {
triggeredEntity: cached.triggeredEntity,
triggeredEntityPosition: cached.triggeredEntityPosition ? { ...cached.triggeredEntityPosition } : undefined,
triggeredEntityRotation: cached.triggeredEntityRotation ? { ...cached.triggeredEntityRotation } : undefined,
eventType: 1 /* TriggerAreaEventType.TAET_STAY */,
timestamp: currentTimestamp,
trigger
};
// Refresh trigger-area entity transform when it is scene-owned.
const triggerAreaTransform = Transform.getOrNull(triggerAreaEntity);
if (triggerAreaTransform !== null) {
result.triggeredEntityPosition = { ...triggerAreaTransform.position };
result.triggeredEntityRotation = { ...triggerAreaTransform.rotation };
}
// Refresh triggerer transform when it is scene-owned.
// For player-avatar entities (reserved, no scene-side Transform) the cached values are kept.
const triggererTransform = Transform.getOrNull(triggererEntity);
if (triggererTransform !== null && result.trigger) {
result.trigger.position = { ...triggererTransform.position };
result.trigger.rotation = { ...triggererTransform.rotation };
result.trigger.scale = { ...triggererTransform.scale };
}
return result;
}
/**
* @internal
*/
export function createTriggerAreaEventsSystem(engine) {
const triggerAreaResultComponent = components.TriggerAreaResult(engine);
const Transform = components.Transform(engine);
const entitiesMap = new Map();
function hasCallbacksMap(entity) {
return entitiesMap.has(entity) && entitiesMap.get(entity) !== undefined;
}
function addEntityCallback(entity, triggerType, callback) {
if (hasCallbacksMap(entity)) {
entitiesMap.get(entity).triggerCallbackMap.set(triggerType, callback);
}
else {
entitiesMap.set(entity, {
triggerCallbackMap: new Map([[triggerType, callback]]),
lastConsumedTimestamp: -1,
insideTriggerers: new Map()
});
}
}
function removeEntityCallback(entity, triggerType) {
if (!entitiesMap.has(entity) || !entitiesMap.get(entity).triggerCallbackMap.has(triggerType))
return;
const triggerCallbackMap = entitiesMap.get(entity).triggerCallbackMap;
triggerCallbackMap.delete(triggerType);
// Remove entity if no more trigger callbacks are registered.
// insideTriggerers is intentionally left populated so that re-subscription picks up
// in-flight sessions without missing the first synthesized onStay.
if (triggerCallbackMap.size === 0)
entitiesMap.delete(entity);
}
function onTriggerEnter(entity, cb) {
addEntityCallback(entity, 0 /* TriggerAreaEventType.TAET_ENTER */, cb);
}
function removeOnTriggerEnter(entity) {
removeEntityCallback(entity, 0 /* TriggerAreaEventType.TAET_ENTER */);
}
function onTriggerStay(entity, cb) {
addEntityCallback(entity, 1 /* TriggerAreaEventType.TAET_STAY */, cb);
}
function removeOnTriggerStay(entity) {
removeEntityCallback(entity, 1 /* TriggerAreaEventType.TAET_STAY */);
}
function onTriggerExit(entity, cb) {
addEntityCallback(entity, 2 /* TriggerAreaEventType.TAET_EXIT */, cb);
}
function removeOnTriggerExit(entity) {
removeEntityCallback(entity, 2 /* TriggerAreaEventType.TAET_EXIT */);
}
engine.addSystem(function TriggerAreaResultSystem() {
const garbageEntries = [];
for (const [entity, data] of entitiesMap) {
if (engine.getEntityState(entity) === EntityState.Removed) {
garbageEntries.push(entity);
continue;
}
const result = triggerAreaResultComponent.get(entity);
// -----------------------------------------------------------------------
// Pass 1: drain new GOVS events
// -----------------------------------------------------------------------
// The Explorer may be taking time before the result component is put.
if (result.size > 0) {
const values = Array.from(result.values());
// Determine starting index for new values (more than one could be added between System updates).
// Search backwards to find the anchor at lastConsumedTimestamp.
let startIndex = 0;
if (data.lastConsumedTimestamp >= 0) {
const newestTimestamp = values[values.length - 1].timestamp;
// If nothing new, skip processing.
if (newestTimestamp > data.lastConsumedTimestamp) {
// Find index of value with the lastConsumedTimestamp.
let i = values.length - 2;
while (i >= 0 && values[i].timestamp > data.lastConsumedTimestamp)
i--;
// Mark the following value index as the starting point to trigger all the new value callbacks.
startIndex = i + 1;
}
else {
// No new events — skip to Pass 2.
startIndex = values.length;
}
}
if (startIndex < values.length) {
// Process new wire events in chronological order.
for (let i = startIndex; i < values.length; i++) {
const event = values[i];
switch (event.eventType) {
case 0 /* TriggerAreaEventType.TAET_ENTER */:
// Update in-flight tracking before firing the callback.
data.insideTriggerers.set(event.trigger.entity, {
triggeredEntity: event.triggeredEntity,
triggeredEntityPosition: event.triggeredEntityPosition
? { ...event.triggeredEntityPosition }
: undefined,
triggeredEntityRotation: event.triggeredEntityRotation
? { ...event.triggeredEntityRotation }
: undefined,
eventType: event.eventType,
timestamp: event.timestamp,
trigger: event.trigger
? {
entity: event.trigger.entity,
layers: event.trigger.layers,
position: event.trigger.position ? { ...event.trigger.position } : undefined,
rotation: event.trigger.rotation ? { ...event.trigger.rotation } : undefined,
scale: event.trigger.scale ? { ...event.trigger.scale } : undefined
}
: undefined
});
if (data.triggerCallbackMap.has(0 /* TriggerAreaEventType.TAET_ENTER */)) {
data.triggerCallbackMap.get(0 /* TriggerAreaEventType.TAET_ENTER */)(event);
}
break;
case 2 /* TriggerAreaEventType.TAET_EXIT */:
data.insideTriggerers.delete(event.trigger.entity);
if (data.triggerCallbackMap.has(2 /* TriggerAreaEventType.TAET_EXIT */)) {
data.triggerCallbackMap.get(2 /* TriggerAreaEventType.TAET_EXIT */)(event);
}
break;
// Wire-level TAET_STAY and any unknown event types are ignored — no callback, no state mutation.
}
}
data.lastConsumedTimestamp = values[values.length - 1].timestamp;
}
}
// -----------------------------------------------------------------------
// Pass 2: synthesize per-tick onStay callbacks
// -----------------------------------------------------------------------
// Only run if an onStay callback is registered and there are tracked triggerers.
if (data.triggerCallbackMap.has(1 /* TriggerAreaEventType.TAET_STAY */) &&
data.insideTriggerers.size > 0) {
const onStay = data.triggerCallbackMap.get(1 /* TriggerAreaEventType.TAET_STAY */);
const currentTimestamp = Date.now();
for (const [triggererEntity, cachedResult] of data.insideTriggerers) {
onStay(buildSyntheticStayResult(cachedResult, entity, triggererEntity, currentTimestamp, Transform));
}
}
}
// Clean up garbage entries.
garbageEntries.forEach((garbageEntity) => entitiesMap.delete(garbageEntity));
});
return {
onTriggerEnter,
removeOnTriggerEnter,
onTriggerStay,
removeOnTriggerStay,
onTriggerExit,
removeOnTriggerExit
};
}