barsnadcat / sideviewshootemup

HMS "Sunflower" project.

Physics based arcade ship builder.

Question:

What is the optimal way to replicate the behavior of Highfleet ships in Unreal engine?

Requirements:

• Ship is collections of parts that rigidly joined together affected by gravity and moves using thrusters
• Each part takes damage individually, can be destroyed so ship can be split
• Guns can be placed inside ship -- projectiles they spawn do not collide with ship itself, only with enemy ship, other projectiles
• Player character can run inside the ship, and is affected by ship movement

Constraints approach

Ship parts connected together using FConstraintInstance.

Nice:

• Very simple code
• We can add snapping and bending as features

Bad:

• Physic simulation take a lot of CPU - this will no run on mobile for sure

Really bad:

• Ship is not rigid

More constraints approach

Add long distance constraints.

Nice:

• We can add snapping and bending as features

Not great:

• Messy code to split ship
• Ship is sort of rigid but no 100%

Bad:

• Even worse performance

Welding approach

Ship parts connected together using AttachToComponent with bWeldSimulatedBodies = true

Really nice:

• Very cheap simulation - should run on mobile

Nice:

• Ship is 100% rigid

Bad:

• Attachment is directed graph, wile ship is undirected - so additional layer of conde is needed

Really bad:

• Unwelding parts generates spikes up to 200ms on big ships

Batch unweld chaos mod

Add Batch unweld to MeshComponent, FBodyInstance and chaos.

Not tested yet, performance fix is not given.

Bad:

• Extra maintenance cost associated with engine modification.

Lego fortnite approach

Use FClusterUnion and FGeometryCollection.

• FClusterUnionManager
  • FClusterUnionPhysicsProxy
    • UClusterUnionComponent (5.3)
      • AClusterUnionActor
      • ChaosModularVehicle (5.4)