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Health Deduction System

Source file: client/engine/systems/systems_functions/HealthDeductionSystem.cpp

Purpose: Handle projectile/target collisions, apply damage, trigger hit/death animations, and clean up destroyed entities.

Components used:

  • Health (current hit points)
  • HealthBar (damage timer refresh)
  • AnimatedSprite ("Hit" and "Death" animations)
  • HitBox (AABB collision)
  • Transform (positions for AABB test)
  • Projectile (damage, ownership)
  • PlayerTag / EnemyTag (friend/foe filtering)
  • TimedEvents, FrameEvents, PatternMovement (removed on death)

Behavior​

  • For each entity with Health, iterates projectiles and tests collision via IsColliding (AABB).
  • Skips friendly fire based on projectile.isEnemyProjectile against Player/Enemy tags.
  • On impact:
    • Decrements health.currentHealth by projectile.damage.
    • Resets health_bar.timer_damage to 0 if present.
    • Plays "Hit" animation and forces frame 1 if AnimatedSprite exists.
    • Removes Projectile from the projectile entity; if it has a sprite, plays "Death" and adds AnimationDeath, otherwise kills it.
  • If health.currentHealth <= 0, invokes DeathHandling: adds AnimationDeath, removes Health, HitBox, Player/Enemy tags, TimedEvents, FrameEvents, PatternMovement, then plays "Death" if available or kills the entity.

Main signature​

void HealthDeductionSystem(Eng::registry &reg,
    Eng::sparse_array<Component::Health> &healths,
    Eng::sparse_array<Component::HealthBar> &health_bars,
    Eng::sparse_array<Component::AnimatedSprite> &animated_sprites,
    Eng::sparse_array<Component::HitBox> const &hitBoxes,
    Eng::sparse_array<Component::Transform> const &transforms,
    Eng::sparse_array<Component::Projectile> const &projectiles);

Notes​

  • AABB checks include offsets/scales via IsColliding (see CollidingTools).
  • "Hit"/"Death" handling assumes non-looping projectile animations.
  • Entities with no collision or remaining health are unaffected.