SekaiBlender

MMD-native workflows for Blender.
PMX/VMD assets, animation, IK, physics and rendering in one Windows build.

Download · Features · Build · Known limits · Contributing

SekaiBlender is a source-level Blender branch for MMD creators. It is a standalone application, not an add-on, and it does not replace an existing Blender installation.

Download

A prebuilt Windows x64 package is published on the Releases page, so building from source is optional.

Download sekaiblender-1.0-git.<hash>-windows64.zip (about 329 MB) from the latest release.
Extract it anywhere. No installer and no administrator rights are required.
Run SekaiBlender-launcher.exe from the extracted folder. Use SekaiBlender.exe directly if you want the console window attached.

Keep the extracted folder intact: the executables load the 5.3 runtime directory that sits next to them.

At A Glance

Workflow	Included
PMX	Native import and export, materials, UVs, morphs, bones, rigid bodies and joints
VMD	Bone, morph and camera animation with Bezier interpolation
IK	Native CCD V8 solver with PMX schema 1/2 support and angle limits
Physics	Realtime Bullet preview, multi-model scenes and deterministic Action Bake
Viewport	MMD toon outlines, EEVEE workflows and AMD FSR 1.0 upscaling

Feature Set

PMX Asset Pipeline

PMX 2.0 import for BDEF/SDEF skinning, IK, append transforms, axis limits, materials, UVs, morphs and display frames.
PMX export for imported models, including source retention, vertex morph offsets, physics definitions and packaged textures.
Round-trip validation against real PMX models with field-by-field comparison across all 11 major sections.

Animation And Camera

VMD bone and morph Actions with position, quaternion and Bezier interpolation.
Native VMD camera import and export with perspective/orthographic support.
Camera rig export preserves per-channel Bezier curves when the source uses the supported rig layout.

Realtime Physics

Frame-authoritative realtime preview with independent Bullet worlds per model.
Multiple MMD models in the same Scene.
F8 Action Bake with progress, cancellation recovery, NLA validation and provenance metadata.

Rendering And Look Development

MMD edge preview driven by PMX edge_flag and edge_size.
AMD FSR 1.0 EASU/RCAS quality presets for the EEVEE viewport and renders.
SekaiBlender branding, Chinese UI defaults and a 30 FPS startup timeline.

Verified Workflows

Check	Result
PMX / VMD / Blender kernel tests	3/3 CTest suites passing
PMX, MMD and VMD direct tests	170 passed, 11 environment-gated skips, 0 failed
PMX export round-trip	2 real PMX models, all 11 sections matched
VMD camera round-trip	Real 27-frame sample, zero resampling error

Build On Windows

Requirements

Visual Studio 2022 with MSVC v143 or newer
CMake 3.21 or newer
Python 3.11 for the embedded runtime
Git LFS and Git submodules
CUDA Toolkit and OptiX SDK are optional GPU acceleration dependencies

Clone

git clone --recurse-submodules https://github.com/ShiJieWorld/SekaiBlender.git
cd SekaiBlender
git lfs install
git lfs pull
git submodule update --init --recursive

The repository uses Git LFS for Blender test assets and other binary resources. The initial LFS download is large.

Configure, Build And Run

cmake -S . -B ..\build -G "Visual Studio 18 2026" -A x64 `
  -DWITH_CYCLES_CUDA_BINARIES=ON `
  -DWITH_CYCLES_DEVICE_OPTIX=ON

cmake --build ..\build --config Release --target INSTALL
..\build\bin\Release\SekaiBlender.exe

Use the generator matching the installed Visual Studio version: Visual Studio 17 2022 uses Visual Studio 17 2022, while Visual Studio 18 2026 uses Visual Studio 18 2026.

For a CPU-only build, omit the CUDA and OptiX options. The INSTALL target is intentional: it refreshes the runtime 5.3/scripts tree used by the packaged executable.

Known Limits

The MMD → Rigify integration (mmd_native_ik_override, Rigify scene VMD playback) is still in testing: prototype workflows validated on two reference models so far; K-frame baking and toe/heel roll controls are pending.
VMD light and self-shadow frames are not imported or exported.
Vertex and Group→Vertex Morphs have viewport effects; Bone, UV, Material, Flip and Impulse Morph data are retained but do not all map to active Blender effects yet.
QDEF and SDEF are evaluated as linear blend skinning rather than true QDEF/SDEF.
PMX export currently accepts models imported by SekaiBlender with source-retention data; arbitrary native Blender meshes are rejected rather than exported with guessed semantics.
Realtime preview may ring at startup; use Action Bake for final output, and damping 0.15 can suppress animal-ear motion.
Realtime physics sessions are independent per model within one Scene. Different Scenes cannot own simultaneous global realtime schedulers.

Project Status

This GitHub main branch is an intentionally history-trimmed source snapshot. It contains the complete current source tree and SekaiBlender modifications, while the upstream Blender commit history is kept out of this public snapshot to keep the repository practical to clone and maintain.

Contributing

Bug reports and focused pull requests are welcome. For changes to PMX, VMD, IK or physics, include the smallest reproducible asset or test case available and describe the expected Blender-side result.

License And Upstream

SekaiBlender is a GPL-compatible Blender branch. It inherits the GNU General Public License v2.0 or later.

Upstream Blender: blender/blender
Blender website: blender.org
PMX format reference: PMX format notes

_{Built for creators who bring MMD worlds to life.}