HoloRoll

See your animation while you score it.

HoloRoll plugs into REAPER and shows your 3D animation right inside the DAW. The animation plays in lock-step with the playhead, so when you're picking a sound for a footstep, a sword swing, or a UI flourish, you can actually watch the moment instead of guessing from a waveform. Drop a .glb from Blender into your project's animations folder, and it shows up on the timeline as a media item you can move, copy, and layer sounds on top of.

Status: 0.11.1. Drop animations from Blender into a folder, get them on the timeline, design sound to match. Everything below works today on Windows.

Coming next: Unreal Engine integration. A live bridge from your Unreal project so HoloRoll can pull animations directly from sequences without exporting .glb files manually. This is the headline feature we're building toward — the file-based workflow here is the foundation it'll sit on top of.

See CHANGELOG.md for what's shipped and ROADMAP.md for what's next.

What it does

• Watch animations on the timeline. Each animation is a media item. The viewport renders whatever item is under the playhead, so you scrub motion the same way you scrub audio.
• Drop and go. Save a .glb from Blender into <project>/Animations/<project_name>/, drag it onto the viewport, or drop it in the global Incoming folder — HoloRoll picks it up within a second and asks if you want to place it.
• Variations for sound design. One animation, many items. Set Variations to 3 and you get door_open, door_open_02, door_open_03 — same motion, different items, layer different sounds on each.
• Pre-roll / post-roll buffers. When the playhead sits a second before an item, the viewport already shows frame 0. After the item, the last frame holds. Gives you breathing room for anticipation whooshes and tail reverbs without affecting the item's actual length.
• Scale awareness. A 1.80 m reference figure stands next to your model so you can eyeball whether you're scoring a person, a Godzilla, or a doorknob. Dimensions plate in the corner shows the live bbox in metres.
• 3/4 default framing. New animations snap to a Blender-style front-right-top view, with the camera distance auto-fit to the model.

Formats

.glb (skinned glTF) is the primary format. Export from Blender's File → Export → glTF 2.0 with Animation enabled. Multiple animations in one file become separate library entries.

.mdd (Blender Point Cache) is also supported, for vertex-level animation that doesn't fit a skinned rig (cloth sims, soft bodies, shape-deforming effects). Pair it with a matching .obj for full shading; without an .obj you get a points-only render.

Installation

From installer (recommended)

1. Download HoloRoll-Setup-<version>.exe from the Releases page.
2. Run it. The installer detects your REAPER plugin folder automatically.
3. Restart REAPER. Run the action HoloRoll: Toggle Viewport from the Action List (or assign it a hotkey).

The installer supports headless invocation — see docs/headless_install.md.

From source

git clone https://github.com/Ilia-Smelkov/HoloRoll.git
cd HoloRoll
.\scripts\bootstrap.ps1 -Preset x64-Release -DeployToReaper -KillReaper -RestartReaper

Requirements: Windows 10/11 x64, Visual Studio 2022, CMake 3.24+.

Quick start

1. Save your REAPER project (HoloRoll uses the project folder).
2. Action List → HoloRoll: Toggle Viewport.
3. Drag a .glb from Explorer onto the HoloRoll viewport.
4. Click Place all in the modal that appears.
5. Press Play. The item under the playhead drives the viewport.

Camera controls

Input	Action
RMB hold + drag	Mouse-look
RMB hold + WASD	Fly forward / back / strafe
RMB hold + Q / E	Move down / up
Mouse wheel	Adjust fly speed
LMB drag on rotation gizmo arc	Rotate object around that axis
Reset camera button	Snap to 3/4 default framing

Roadmap

See ROADMAP.md for the full plan.

The big one: Unreal Engine bridge. Live link between an Unreal project and HoloRoll, so animations and sequences come straight from the game without going through .glb exports. This is what HoloRoll is ultimately built for — game audio designers scoring directly against the actual in-engine motion. The current .glb workflow is the groundwork for that pipeline.

Other planned work: Unity bridge, motion analysis (auto-detect bone movement keypoints to suggest hit timings), region manager UI, full UI presentation pass.

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Format details

If you just want to use HoloRoll, you don't need this section.

GLB

Standard glTF 2.0 binary. HoloRoll loads the first skinned mesh's first primitive, walks the joint hierarchy, samples animation channels at the configured fps, and bakes per-frame vertex positions via linear blend skinning on load.

Supported:

• LINEAR and STEP interpolation
• UBYTE / USHORT joint indices, FLOAT / UBYTE / USHORT joint weights
• glTF default coordinate space (Y-up, right-handed)

Not supported:

• Morph targets / vertex animation without skinning
• CUBICSPLINE keyframes (silently degraded to LINEAR)
• Multiple meshes / multiple primitives per mesh (first wins)
• Embedded textures (stripped on load — HoloRoll uses Lambert grayscale)

Multiple animations inside one .glb produce separate library entries: <filestem>.<animname> (or <filestem>.<index> if unnamed).

MDD

Big-Endian Blender Point Cache. Layout: int32 totalFrames, int32 totalPoints, then float32 times[totalFrames], then float32 coords[totalFrames × totalPoints × 3].

OBJ pairing:

1. Same basename: walk.mdd ↔ walk.obj
2. Fallback: any OBJ in the folder whose vertex count matches the MDD's totalPoints. One character.obj can serve character_idle.mdd, character_walk.mdd, etc.

Folder layout

<project_dir>/
  MyLevel.rpp
  Animations/
    MyLevel/             <-- per-project subfolder, isolated
      door_open.glb
      character_idle.glb

Global Incoming folder (auto-routes into the active project): %APPDATA%\REAPER\UserPlugins\HoloRollIncoming\

Config

%APPDATA%\REAPER\UserPlugins\holoroll_config.ini:

fps=24
region_gap_seconds=1
region_name_prefix=
hot_reload.enabled=1
scene.show_ground_plane=1
scene.ground_radius=20
scene.grid_step=1
scene.show_bbox_dimensions=1
scene.show_grid_labels=1
scene.show_reference_human=1
placement.variations=1
placement.pre_roll_seconds=1
placement.post_roll_seconds=1
placement.region_overhang_seconds=0.5

Actions registered in REAPER

Command	Description
HoloRoll: Toggle Viewport	Show / hide the docked viewport
HoloRoll: Choose Animations Folder	Override the project's default folder
HoloRoll: Place All Animation Regions	Place one item + region per animation
HoloRoll: Open Config File	Open holoroll_config.ini in editor
HoloRoll: Reload Config	Re-read the config from disk

Contributing

Bug reports and PRs are welcome. See CONTRIBUTING.md.

License

MIT — Copyright (c) 2026 Ilia Smelkov / Muted Games.

Third-party components:

• REAPER SDK in third_party/reaper-sdk/ — © Cockos Inc., distributed under its own permissive license.
• ImGui — © Omar Cornut and contributors, MIT-licensed.
• tinygltf — © Syoyo Fujita and contributors, MIT-licensed.