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GameObjectSpawnSystem.ixx File

System for processing spawn schedules and enqueuing spawn commands. More...

Included Headers​

#include <cassert> #include <memory> #include <vector> #include <helios.engine.runtime.spawn.scheduling.SpawnScheduler> #include <helios.engine.runtime.spawn.commands.ScheduledSpawnPlanCommand> #include <helios.engine.runtime.world.UpdateContext> #include <helios.engine.runtime.messaging.command.CommandBuffer> #include <helios.engine.runtime.spawn.events.SpawnPlanCommandExecutedEvent> #include <helios.engine.ecs.System>

Namespaces Index​

namespacehelios
namespaceengine

Main engine module aggregating core infrastructure and game systems. More...

namespacemechanics

High-level gameplay systems and components for game logic. More...

namespacespawn

Entity spawning and lifecycle management. More...

namespacesystems

Systems for spawn lifecycle management. More...

Classes Index​

classGameObjectSpawnSystem

System that evaluates spawn conditions and enqueues spawn commands. More...

Description​

System for processing spawn schedules and enqueuing spawn commands.

File Listing​

The file content with the documentation metadata removed is:

1/**
2 * @file GameObjectSpawnSystem.ixx
3 * @brief System for processing spawn schedules and enqueuing spawn commands.
4 */
5module;
6
7#include <cassert>
8#include <memory>
9#include <vector>
10
11export module helios.engine.mechanics.spawn.systems.GameObjectSpawnSystem;
12
13import helios.engine.ecs.System;
14import helios.engine.runtime.messaging.command.CommandBuffer;
15import helios.engine.runtime.world.UpdateContext;
16import helios.engine.runtime.spawn.commands.ScheduledSpawnPlanCommand;
17import helios.engine.runtime.spawn.scheduling.SpawnScheduler;
18import helios.engine.runtime.spawn.events.SpawnPlanCommandExecutedEvent;
19
20export namespace helios::engine::mechanics::spawn::systems {
21
22 /**
23 * @brief System that evaluates spawn conditions and enqueues spawn commands.
24 *
25 * @details GameObjectSpawnSystem bridges the spawn scheduling logic with the
26 * command-based spawning pipeline. It manages multiple SpawnScheduler instances
27 * and performs the following each frame:
28 *
29 * 1 **Read Frame Events:** Consumes `SpawnPlanCommandExecutedEvent` from the
30 * previous frame to commit completed spawn operations to all schedulers.
31 *
32 * 2 **Evaluate Conditions:** Calls `SpawnScheduler::evaluate()` on each
33 * scheduler to check all registered spawn rules against their conditions.
34 *
35 * 3 **Drain Scheduled Plans:** Retrieves all plans that are ready to execute
36 * and enqueues them as `ScheduledSpawnPlanCommand` into the CommandBuffer.
37 *
38 * The actual spawning is performed by the command dispatcher/manager layer,
39 * keeping this system focused on scheduling logic only.
40 *
41 * Example setup:
42 * ```cpp
43 * std::vector<std::unique_ptr<SpawnScheduler>> schedulers;
44 *
45 * auto enemyScheduler = std::make_unique<SpawnScheduler>();
46 * enemyScheduler->addRule(enemyProfileId, std::move(enemyRule));
47 * schedulers.push_back(std::move(enemyScheduler));
48 *
49 * auto powerupScheduler = std::make_unique<SpawnScheduler>();
50 * powerupScheduler->addRule(powerupProfileId, std::move(powerupRule));
51 * schedulers.push_back(std::move(powerupScheduler));
52 *
53 * auto spawnSystem = std::make_unique<GameObjectSpawnSystem>(schedulers);
54 * mainPhase.addPass().add(std::move(spawnSystem));
55 * ```
56 *
57 * @note This system reads frame-level events via `readFrame()`, meaning it
58 * processes spawn confirmations from the previous frame.
59 *
60 * @see SpawnScheduler
61 * @see ScheduledSpawnPlanCommand
62 * @see SpawnPlanCommandExecutedEvent
63 */
64 class GameObjectSpawnSystem : public helios::engine::ecs::System {
65
66 /**
67 * @brief Collection of schedulers that manage spawn rules and conditions.
68 *
69 * @details Each scheduler owns and evaluates its registered spawn rules
70 * independently. When conditions are met, the scheduler produces
71 * ScheduledSpawnPlan instances for execution. Multiple schedulers allow
72 * grouping spawn rules by category (e.g., enemies, powerups, projectiles).
73 */
74 std::vector<std::unique_ptr<helios::engine::runtime::spawn::scheduling::SpawnScheduler>> spawnSchedulers_;
75
76 public:
77
78 /**
79 * @brief Constructs a GameObjectSpawnSystem with the given schedulers.
80 *
81 * @param spawnSchedulers Vector of schedulers managing spawn rules.
82 * Ownership of all schedulers is transferred to this system.
83 */
84 explicit GameObjectSpawnSystem(
85 std::vector<std::unique_ptr<helios::engine::runtime::spawn::scheduling::SpawnScheduler>> spawnSchedulers
86 ) :
87 spawnSchedulers_(std::move(spawnSchedulers)) {}
88
89 /**
90 * @brief Processes spawn scheduling and enqueues spawn commands.
91 *
92 * @details Iterates through all schedulers and performs these steps for each:
93 * 1 Reads `SpawnPlanCommandExecutedEvent` from frame event bus
94 * 2 Commits completed spawns to the scheduler (for tracking/cooldowns)
95 * 3 Evaluates all spawn rules against current conditions
96 * 4 Drains ready spawn plans and enqueues them as commands
97 *
98 * @param updateContext The current frame's update context.
99 */
100 void update(helios::engine::runtime::world::UpdateContext& updateContext) noexcept override {
101
102 const auto& events = updateContext.readFrame<
103 helios::engine::runtime::spawn::events::SpawnPlanCommandExecutedEvent
104 >();
105
106 for (const auto& spawnScheduler : spawnSchedulers_) {
107
108 /**
109 * @todo this should be processed before iterating over all schedulers: A scheduler owns the rule,
110 * hence a rule that triggered the event's can be associated with the owning Scheduler, making it
111 * unneccesary to iterate over already processed events
112 */
113 for (const auto& event : events) {
114 spawnScheduler->commit(event.spawnRuleId, event.spawnCount);
115 }
116
117 spawnScheduler->evaluate(updateContext);
118
119 auto scheduledPlans = spawnScheduler->drainScheduledPlans();
120
121 for (auto& plan : scheduledPlans) {
122 updateContext.commandBuffer().add<
123 helios::engine::runtime::spawn::commands::ScheduledSpawnPlanCommand
124 >(
125 plan.spawnProfileId, plan.spawnPlan, plan.spawnContext
126 );
127 }
128 }
129
130 }
131
132 };
133
134}

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