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HealthComponent

Location: shared/include/components/HealthComponent.hpp (planned)

The HealthComponent manages the health pool for damageable entities.

Structure

struct HealthComponent {
    std::int32_t current = 1;      // Current HP
    std::int32_t max = 1;          // Maximum HP
    bool invulnerable = false;     // If true, ignores incoming damage
};

Fields

Field Type Default Description
current int32_t 1 Current health points
max int32_t 1 Maximum health points
invulnerable bool false If true, entity cannot take damage

Invariants

  • 0 <= current <= max
  • max >= 0

Usage

Creating Entity with Health

registry.emplace<HealthComponent>(player, HealthComponent{
    100,   // current HP
    100,   // max HP
    false  // not invulnerable
});

Applying Damage

auto& health = registry.get<HealthComponent>(enemy);

if (!health.invulnerable) {
    health.current -= damage;
    health.current = std::max(0, health.current);  // Clamp to 0
}

if (health.current <= 0) {
    registry.destroyEntity(enemy);
}

Healing

auto& health = registry.get<HealthComponent>(player);

health.current += healAmount;
health.current = std::min(health.current, health.max);  // Clamp to max

Systems

  • CollisionSystem — Applies damage from hits
  • DestructionSystem — Removes entities when current <= 0
  • UI/HUD — Displays health bars

Networking

  • Replicate current on change
  • Replicate max on spawn
  • Don't replicate invulnerable (server-only state)

Examples

Boss with High HP

registry.emplace<HealthComponent>(boss, HealthComponent{5000, 5000, false});

Invulnerable Player (during respawn)

auto& health = registry.get<HealthComponent>(player);
health.invulnerable = true;  // Temporary invincibility

// After 3 seconds
health.invulnerable = false;