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Fetch the complete documentation index at: https://mintlify.com/AmyangXYZ/reze-studio/llms.txt

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Reze Studio is a fully browser-native application — it has no server and no cloud storage. Model loading uses the browser’s File System Access API (via an <input> element with webkitdirectory) to read an entire local folder at once, giving the engine access to the .pmx file alongside every texture it references. The loaded model replaces the current one in the viewport immediately, and the left-panel Bone, Morph, and Materials lists all update to reflect the new skeleton.

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Loading a PMX folder

1

Open the File menu

Click File in the top-left menu bar, then select Load PMX folder….
2

Select the model folder

Your browser’s folder-picker dialog opens. Navigate to and select the folder that contains your .pmx file. All textures, toon maps, and sphere maps must be inside that folder or its subfolders — the engine resolves texture paths relative to the .pmx location.
3

Choose a PMX if the folder contains more than one

If the selected folder contains multiple .pmx files, a small picker appears beneath the File menu. Use the dropdown to choose the correct file, then click Load selected PMX.
4

Model loads in the viewport

The engine removes the previous model, loads the new one (including IK and physics), and updates the Bones panel, the Morphs panel, and the Materials panel. The viewport renders the new model immediately on the next frame.
Loading a new PMX model is not undoable. It does not go on the undo/redo history stack — doing so would desync the undo target from the loaded skeleton. Make sure you have exported any work you want to keep before swapping models.

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Texture co-location requirement

PMX files reference textures by relative path. The engine resolves those paths against the folder you selected, so a texture referenced as tex/body.png must exist at <your-folder>/tex/body.png. Placing the .pmx alone in a folder and keeping textures elsewhere will cause them to fail to load — the model will still appear, but surfaces will render without their textures. Best practice: keep the .pmx and its entire companion folder structure together and select the root of that folder when prompted.

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The default bundled model

When Reze Studio first opens, it automatically loads a default model so you can start editing right away without having any local PMX files. The bundled model is served from the application’s own assets: 
/models/塞尔凯特/塞尔凯特.pmx
This path is defined as MODEL_PATH in engine-bridge.tsx. The engine loads it under the internal name "reze". Once the engine finishes initializing, it also loads the bundled sample animation on top of the default model so the viewport is live from the very first render.
The bundled model sets a specific morph weight (抗穿模 = 0.5) on load to prevent mesh clipping artifacts. When you load a custom PMX this morph is not applied unless your model also defines a morph with the same name.

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Swapping models with an active clip

If you already have animation data in the timeline when you load a new PMX, Reze Studio does not discard your work outright. Instead, it runs a retention pass via clipRetainedForModel, which:
  1. Keeps every bone track whose bone name exists in the new model’s skeleton.
  2. Discards every bone track whose bone name does not exist in the new skeleton.
  3. Keeps every morph track whose morph name exists in the new model’s morph list.
  4. Discards every morph track whose morph name does not exist in the new morph list.
  5. Recalculates frameCount as Math.max(original frameCount, latest retained keyframe). If all tracks were dropped (empty result), frameCount falls back to Math.max(original frameCount, DEFAULT_STUDIO_CLIP_FRAMES).
The clip display name and the playhead position are preserved. If the retained clip ends up empty (no tracks survived), Reze Studio still keeps the original clip display name — a fresh blank clip with a name derived from the model’s filename stem is only created when there was no prior timeline at all (e.g. on a brand-new session).
Bone and morph names in MMD are Japanese strings (e.g. 上半身 for Upper Body, 左腕 for Left Arm). A custom PMX that uses the same conventional Japanese bone names as a standard MMD model will retain the most tracks when swapping.

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Bone list after loading

After a model loads, the left panel shows all skeleton bones organized into named groups. The groups are defined in lib/animation.ts as BONE_GROUPS:
GroupContents
All BonesEvery bone in the skeleton (no filter)
Upper BodyHead, neck, chest, upper torso, waist (頭, 首, 上半身, 上半身2, 胸, 首根元, 腰)
Left ArmLeft shoulder through wrist and twist bones
Right ArmRight shoulder through wrist and twist bones
Left HandLeft wrist and all left finger joints
Right HandRight wrist and all right finger joints
Lower BodyPelvis, legs, knees, ankles, toes, centre/groove root, and IK targets
Bones that appear in the current clip are highlighted in the list regardless of which group is active. Clicking a group header filters the list to that group; clicking the same header again collapses back to All Bones.
The File System Access API (the webkitdirectory folder picker) is supported in Chromium-based browsers (Chrome, Edge, Opera) and in Firefox. It is not available in Safari on iOS or macOS as of mid-2025. If the folder picker does not open or produces no result, try Chrome or Edge on a desktop.

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