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Move2DSystem.ixx File

System for processing 2D movement physics. More...

Included Headers​

#include <algorithm> #include <cassert> #include <cmath> #include <helios.engine.mechanics.lifecycle.components.Active> #include <helios.engine.runtime.world.UpdateContext> #include <helios.engine.modules.physics.motion.components.DirectionComponent> #include <helios.engine.modules.spatial.transform.components.TranslationStateComponent> #include <helios.engine.runtime.world.GameWorld> #include <helios.math> #include <helios.engine.modules.physics.motion.components.Move2DComponent> #include <helios.engine.ecs.System>

Namespaces Index​

namespacehelios
namespaceengine

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

namespacemodules

Domain-specific components and systems. More...

namespacephysics

Physics simulation and collision detection subsystem for the game engine. More...

namespacemotion

Motion physics components and systems. More...

namespacesystems

Classes Index​

classMove2DSystem

System that processes 2D movement for entities. More...

Description​

System for processing 2D movement physics.

File Listing​

The file content with the documentation metadata removed is:

1/**
2 * @file Move2DSystem.ixx
3 * @brief System for processing 2D movement physics.
4 */
5module;
6
7
8#include <algorithm>
9#include <cassert>
10#include <cmath>
11
12export module helios.engine.modules.physics.motion.systems.Move2DSystem;
13
14
15import helios.engine.ecs.System;
16import helios.math;
17
18import helios.engine.runtime.world.GameWorld;
19import helios.engine.modules.physics.motion.components.Move2DComponent;
20import helios.engine.modules.spatial.transform.components.TranslationStateComponent;
21import helios.engine.modules.physics.motion.components.DirectionComponent;
22
23import helios.engine.runtime.world.UpdateContext;
24
25import helios.engine.mechanics.lifecycle.components.Active;
26
27export namespace helios::engine::modules::physics::motion::systems {
28
29 /**
30 * @brief System that processes 2D movement for entities.
31 *
32 * @details This system reads from Move2DComponent and applies physics simulation
33 * including velocity integration and dampening when input is inactive.
34 *
35 * The system updates TranslationStateComponent with the computed translation
36 * changes each frame.
37 *
38 * Required components:
39 * - Move2DComponent (physics configuration and state)
40 * - DirectionComponent (current movement direction)
41 * - TranslationStateComponent (receives translation updates)
42 */
43 class Move2DSystem : public helios::engine::ecs::System {
44
45 private:
46
47
48
49 /**
50 * @brief Computes translation delta for an entity based on its Move2DComponent state.
51 *
52 * @details Calculates velocity changes based on input state. When input is active,
53 * accelerates in the facing direction. When inactive, applies exponential
54 * drag to slow down. Velocity is clamped to maximum speed.
55 *
56 * @param cmp Pointer to the Move2DComponent.
57 * @param currentDirection The current direction vector from DirectionComponent.
58 * @param deltaTime Frame delta time in seconds.
59 *
60 * @return Translation delta to apply to the entity this frame.
61 */
62 [[nodiscard]] static helios::math::vec3f moveGameObject(
63 helios::engine::modules::physics::motion::components::Move2DComponent* cmp,
64 helios::math::vec3f currentDirection,
65 float deltaTime
66 ) noexcept {
67
68 assert(cmp != nullptr && "Unexpected invalid Move2DComponent passed");
69 assert(deltaTime >= 0 && "Unexpected negative value for deltaTime");
70
71 if (deltaTime == 0) {
72 return helios::math::vec3f{0.0f};
73 }
74
75 bool movementStateChanged = cmp->throttle() > helios::math::EPSILON_LENGTH;
76
77
78 auto velocity = cmp->velocity();
79
80 if (!movementStateChanged) {
81 float movementDampening = cmp->movementDampening();
82
83 // Apply exponential drag when no input is active.
84 // This creates a smooth deceleration effect (velocity approaches zero over time).
85 const float drag = std::pow(movementDampening, deltaTime);
86 velocity = velocity * drag;
87
88 if (velocity.length() <= helios::math::EPSILON_LENGTH) {
89 velocity = {0.0f, 0.0f, 0.0f};
90 }
91
92 } else {
93
94 if (cmp->useInstantAcceleration()) {
95 velocity = currentDirection * cmp->movementSpeed() * cmp->throttle();
96 } else {
97 // Accelerate in the current facing direction.
98 // Uses throttle (input intensity) to scale acceleration.
99 velocity = velocity + (currentDirection * (cmp->movementAcceleration() * cmp->throttle() * deltaTime));
100 }
101
102 }
103
104 // Clamp velocity to maximum speed to prevent unlimited acceleration.
105 if (velocity.length() > cmp->movementSpeed()) {
106 velocity = velocity.normalize() * cmp->movementSpeed();
107 }
108
109 cmp->setVelocity(velocity);
110
111 return (velocity + cmp->inheritedVelocity()) * deltaTime;
112 }
113
114 public:
115
116 /**
117 * @brief Called when the system is added to a GameWorld.
118 *
119 * @param gameWorld Pointer to the GameWorld this system belongs to.
120 */
121 void init(helios::engine::runtime::world::GameWorld& gameWorld) noexcept override {
122 System::init(gameWorld);
123 }
124
125 /**
126 * @brief Updates movement for all applicable entities.
127 *
128 * @details For each entity with Move2DComponent, computes translation
129 * changes and applies them to the TranslationStateComponent.
130 *
131 * @param updateContext Context containing deltaTime and other frame data.
132 */
133 void update(helios::engine::runtime::world::UpdateContext& updateContext) noexcept override {
134
135 for (auto [entity, m2d, dc, tsc, active] : gameWorld_->view<
136 helios::engine::modules::physics::motion::components::Move2DComponent,
137 helios::engine::modules::physics::motion::components::DirectionComponent,
138 helios::engine::modules::spatial::transform::components::TranslationStateComponent,
139 helios::engine::mechanics::lifecycle::components::Active
140 >().whereEnabled()) {
141
142 helios::math::vec3f translationDelta;
143
144 translationDelta = moveGameObject(m2d, dc->direction(), updateContext.deltaTime());
145
146 tsc->translateBy(translationDelta);
147 }
148
149 }
150
151
152 };
153
154};

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