Composite Actor Types - guidebee/OpenRA GitHub Wiki

OpenRA uses composite actors in several cases — not just tanks — to allow for more complex rendering, animation, and logic. A composite actor is one composed of multiple independently rendered parts, often with independent behavior or visuals.

Here are some notable examples of composite actors in OpenRA:

🔧 1. Turreted Tanks (Body + Turret)

Example: medtank, v2rl, artl (RA mod)

  • Traits:

    • WithFacing, RenderSprites – for tank body

    • Turreted, TurretRender – for turret

  • Why composite: Turret rotates independently of movement

💥 2. SAM Sites (Base + Launcher)

Example: sam (RA mod)

  • Traits:

    • WithFacing, RenderSprites – for the base

    • Turreted, TurretRender – for the missile launcher

  • Animation: Launcher raises/rotates to track aircraft

  • Effect: Realistic turret movement even on static structures

🚁 3. Chinook Helicopter (Body + Door)

Example: tran (Transport helicopter)

  • Traits:

    • RenderSprites – for helicopter body

    • RenderableChild or RenderSprites with animation states – for side door

  • Why composite: Door opens when unloading troops

  • Sometimes: Rotors may be animated separately in modded versions

🛠 4. Construction Yards (Building + Crane Arm)

Example: yatech (Yard Tech Center in RA)

  • Traits:

    • RenderSprites – base

    • RenderableChild – crane arm, animated when producing

  • Why composite: To animate just part of the building independently (like a rotating crane arm)

🚀 5. Missile Silos (Silo + Missile Hatch)

Example: mslo (RA nuke silo)

  • Traits:

    • RenderSprites – for the building

    • RenderableChild, Animation – for missile hatch opening

  • Why composite: Hatch opens during launch sequence

🧱 6. Gap Generator (Base + Pulse Effect)

Example: gap (RA)

  • Traits:

    • RenderSprites – base structure

    • RenderableChild or special animation – pulsing overlay effect

  • Why composite: Constant visual effect rendered independently

🔲 7. Mobile Construction Vehicle (MCV)

Example: mcv (RA)

  • Traits:

    • TransformOnDeploy – turns from mobile unit into a building

    • RenderSprites – mobile state

    • Deployment state might have different parts

  • Composite: If modded, MCVs can show folding animations using multiple parts

🎭 8. Modded Units with Add-Ons (Shields, Rotors, Drones)

In community mods or Tiberian Sun-inspired mods, composite actors are used for:

  • Energy shields

  • Hover fans / rotors

  • Turrets mounted on walkers

  • Deployable units with parts that animate during setup

📦 How Are Composite Actors Built?

Traits often involved:

RenderSprites Main body rendering
TurretRender Renders a turret that rotates independently
RenderableChild Renders an attached component (e.g., arm, door)
Turreted Controls turret rotation
WithFacing Controls actor's body facing
Animation Plays frame sequences (e.g., opening doors)

✅ Summary of Composite Actor Types

Actor Type Example Composite Parts
Tank medtank Body + turret
SAM Site sam Base + rotating launcher
Transport Helicopter tran Body + door (or rotor)
Construction Yard yatech Base + crane arm
Missile Silo mslo Base + missile hatch
Gap Generator gap Base + pulse effect
Modded Hovercraft Custom Hull + rotor + shadow
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