Document how to add more damage types

[jdrueckert]

Context

The Health module doc mentions the DamageResistComponent that allows configuring damage types an entity will not be damaged by. Most basic damage types are provided by the Terasology engine code base. There is a minor note on damage types in the Asset System Tutorial. Like all other prefabs, damage types can be modified on module level using Deltas & Overrides. New damage types can further be provided as module assets.

Task

Extend the module docs with information on how to add more damage types.

Open Questions

Should this information be in module-level docs or rather in the engine wiki and only linked to in the Health module docs?

[skaldarnar]

This goes beyond the task of updating the module docs here, but I believe this is the best place to drop my notes:

---

org.terasology.engine.logic.health

Binary "health" system to allow for entities to be destroyed.

Damage types are defined as prefabs. The minimal definition is a prefab with the empty object {}.

Components commonly found in damage type prefabs include:

• BlockDamageModifierComponent
• DamageSoundComponent

In the engine, the following damage types are defined:

• direct in directDamage.prefab
• physical in physicalDamage.prefab
• explosive in explosiveDamage.prefab
• drowning in drowningDamage.prefab
• healing in healingDamage.prefab
• support removed in supportRemovedDamage.prefab

A subset of these damage types is part of the EngineDamageTypes enumeration:

• DIRECT
• PHYSICAL
• EXPLOSIVE
• DROWNING
• HEALING

From these 6 damage types, only 2 damage types are used or referenced in the engine itself.

git grep -e PHYSICAL --or -e engine:physicalDamage \
  -- ':!engine/src/main/java/org/terasology/engine/logic/health/EngineDamageTypes.java'

• physical damage
  • used when destroying block-like entities due to attack by a character (CharacterSystem.java)
  • hitting with an item deals phyiscal damage (itemBase.prefab)
  • (referenced in explosiveDamage.prefab)
• support removed damage
  • used when destroying a block due to missing structural support (for instance, torches) (BlockStructuralSupportSystem.java)
  • used when destroying a block due to missing structural support (SideBlockSupportRequired.java)
  • why do we have this in two places?

---

I propose to:

• only define the damage types required by engine code in the engine itself
  • physical and support removed
• move definitions for damage types used by modules to one of these modules, for instance
  • drowning damage to https://github.com/Terasology/Breathing
  • explosive damage to https://github.com/Terasology/Explosives
  • direct damage to https://github.com/Terasology/Health
• drop other damage types (healing) and remove the EngineDamageTypes enum.