130 lines
5.1 KiB
C++
130 lines
5.1 KiB
C++
/* Copyright (C) 2010 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef INCLUDED_ICMPRANGEMANAGER
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#define INCLUDED_ICMPRANGEMANAGER
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#include "simulation2/system/Interface.h"
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#include "simulation2/helpers/Position.h"
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/**
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* Provides efficient range-based queries of the game world.
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*
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* Possible use cases:
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* - combat units need to detect targetable enemies entering LOS, so they can choose
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* to auto-attack.
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* - auras let a unit have some effect on all units (or those of the same player, or of enemies)
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* within a certain range.
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* - capturable animals need to detect when a player-owned unit is nearby and no units of other
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* players are in range.
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* - scenario triggers may want to detect when units enter a given area.
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* - units gathering from a resource that is exhausted need to find a new resource of the
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* same type, near the old one and reachable.
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* - projectile weapons with splash damage need to find all units within some distance
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* of the target point.
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* - ...
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*
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* In most cases the users are event-based and want notifications when something
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* has entered or left the range, and the query can be set up once and rarely changed.
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* These queries have to be fast. It's fine to approximate an entity as a point.
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*
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* Current design:
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*
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* This class handles just the most common parts of range queries:
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* distance, target interface, and player ownership.
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* The caller can then apply any more complex filtering that it needs.
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*
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* There are two types of query:
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* Passive queries are performed by ExecuteQuery and immediately return the matching entities.
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* Active queries are set up by CreateActiveQuery, and then a CMessageRangeUpdate message will be
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* sent to the entity once per turn if anybody has entered or left the range since the last RangeUpdate.
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* Queries can be disabled, in which case no message will be sent.
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*/
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class ICmpRangeManager : public IComponent
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{
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public:
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/**
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* External identifiers for active queries.
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*/
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typedef u32 tag_t;
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/**
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* Set the bounds of the world.
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* Entities should not be outside the bounds (else efficiency will suffer).
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* @param x0,z0,x1,z1 Coordinates of the corners of the world
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*/
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virtual void SetBounds(entity_pos_t x0, entity_pos_t z0, entity_pos_t x1, entity_pos_t z1) = 0;
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/**
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* Execute a passive query.
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* @param source the entity around which the range will be computed.
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* @param maxRange maximum distance in metres (inclusive).
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* @param owners list of player IDs that matching entities may have; -1 matches entities with no owner.
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* @param requiredInterface if non-zero, an interface ID that matching entities must implement.
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* @return list of entities matching the query, ordered by increasing distance from the source entity.
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*/
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virtual std::vector<entity_id_t> ExecuteQuery(entity_id_t source, entity_pos_t maxRange, std::vector<int> owners, int requiredInterface) = 0;
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/**
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* Construct an active query. The query will be disabled by default.
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* @param source the entity around which the range will be computed.
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* @param maxRange maximum distance in metres (inclusive).
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* @param owners list of player IDs that matching entities may have; -1 matches entities with no owner.
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* @param requiredInterface if non-zero, an interface ID that matching entities must implement.
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* @return unique non-zero identifier of query.
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*/
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virtual tag_t CreateActiveQuery(entity_id_t source, entity_pos_t maxRange, std::vector<int> owners, int requiredInterface) = 0;
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/**
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* Destroy a query and clean up resources. This must be called when an entity no longer needs its
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* query (e.g. when the entity is destroyed).
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* @param tag identifier of query.
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*/
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virtual void DestroyActiveQuery(tag_t tag) = 0;
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/**
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* Re-enable the processing of a query.
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* @param tag identifier of query.
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*/
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virtual void EnableActiveQuery(tag_t tag) = 0;
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/**
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* Disable the processing of a query (no RangeUpdate messages will be sent).
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* @param tag identifier of query.
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*/
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virtual void DisableActiveQuery(tag_t tag) = 0;
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/**
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* Immediately execute a query, and re-enable it if disabled.
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* The next RangeUpdate message will say who has entered/left since this call,
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* so you won't miss any notifications.
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* @param tag identifier of query.
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* @return list of entities matching the query, ordered by increasing distance from the source entity.
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*/
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virtual std::vector<entity_id_t> ResetActiveQuery(tag_t tag) = 0;
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/**
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* Toggle the rendering of debug info.
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*/
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virtual void SetDebugOverlay(bool enabled) = 0;
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DECLARE_INTERFACE_TYPE(RangeManager)
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};
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#endif // INCLUDED_ICMPRANGEMANAGER
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