introduction

Reel

Reel is a custom animation solver that aims to have 1:1 roblox animation solver behavior. It also implements additive and subtractive animation blending.

Installation

Either grab the .rbxm from the latest release

or get it through wally:

reel = "unityjaeger/reel@0.2.0"

Note

Read the reference first to familiarize yourself with the library.

Use Cases

• no instances needed, enabling things like ping compensation for hit detection
• additive and subtractive animation blending
• full control, if you want specific behavior then you can implement that into a custom player

Usage Example

Minimal playback example.

local reel = require(game.ReplicatedStorage.reel)

local animation = reel.animation
local rig_api = reel.rig
local solver = reel.solver

local RunService = game:GetService("RunService")

local sequence = game.ServerStorage.Walk
local character = workspace.Character

local asset = animation.load_keyframe_sequence(sequence)
local rig = rig_api.load_rig(character)
local binding = animation.bind_animation(asset, rig.desc)

local state = {
  binding = binding,
  time_position = 0,
  weight = 1,
  priority = nil, -- use asset.priority
}

local prepared = solver.prepare_tracks({
  { asset = asset, state = state },
})

local started_at = os.clock()

RunService.PreAnimation:Connect(function()
  local elapsed = os.clock() - started_at
  if asset.looped and asset.length > 0 then
    state.time_position = elapsed % asset.length
  else
    state.time_position = math.min(elapsed, asset.length)
  end

  solver.solve_prepared(rig, prepared)

  for index, motor in rig.motors do
    motor.Transform = rig.transforms[index]
  end

  for index, bone in rig.bones do
    bone.Transform = rig.transforms[index]
  end
end)

The one-track path does not need blend scratch. solve_prepared() writes only to rig.transforms; committing Motor6D.Transform, AnimationConstraint.Transform, and Bone.Transform remains the caller’s responsibility.

Frame responsibilities

Before solving, update each active track’s time_position and weight. Reel does not manage speed, loops, fades, stopping, events, or replication.

Prepare the dense track list when its membership or priority structure changes:

prepared = solver.prepare_tracks(current_tracks, prepared)

You may update time_position and weight without preparing again. Re-prepare when a track is added, removed, replaced, or receives a different priority.