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

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In the MMD/PMX format, a morph is a stored shape-key that blends a mesh from a neutral rest shape toward a deformed target at a given weight between 0.0 (fully off) and 1.0 (fully on). Common morph targets include facial expressions (smile, frown, wink), lip shapes for phoneme sync (あ, い, う…), and eye/brow shaping. Reze Studio tracks morph weights as MorphKeyframe objects in the clip’s morphTracks map — one track per named morph — and interpolates them linearly between keyframes during playback. The morph workflow is a simpler version of the bone workflow: no Bézier handle editing, no rotation math, just a weight value at a frame.

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The Morph List Panel

The left panel has two tabs: Bones and Morphs. Click the Morphs tab to reveal a scrollable list of every morph defined in the loaded PMX model. The morphs are listed by their PMX-internal names (typically Japanese). Scrolling, filtering, and layout mirror the bone list.

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Selecting a Morph

Click any morph name in the Morphs tab to select it. Selection is reflected in the studio state as selectedMorph. When a morph is selected:
  • The Properties Inspector switches its content to show the Weight slider for that morph.
  • The dopesheet highlights the morph’s keyframe track.
  • The timeline curve editor switches to the Morph tab, showing the weight curve over time.
Morph selection is mutually exclusive with bone and material selection. Clicking a morph clears any selected bone, and vice versa. Selecting a material in the Materials panel clears both bone and morph selection. This ensures the Properties Inspector always shows exactly one thing at a time.

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Setting Morph Weight

With a morph selected, the Properties Inspector shows a single slider row labelled Weight with a purple accent colour (#c084fc). The slider range is 0.0 to 1.0, displayed with two decimal places. As with bone sliders, there are two interaction modes:
  • Drag the slider thumb: previews the weight live in the viewport at every pointer-move without creating an undo step.
  • Release the pointer: commits the change as a single undo step and triggers an engine clip re-upload.
  • Direct numeric input: click the value field next to the slider to type an exact weight (e.g. 0.75) and press Enter.

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Inserting a Morph Keyframe

Moving the weight slider automatically inserts or updates a morph keyframe at the current playhead frame. The logic mirrors bone auto-insert: no explicit “insert” step is required. If you prefer to insert a keyframe at the current frame without changing the weight, click the Insert button in the Operations section of the Properties Inspector while the morph is selected.

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upsertMorphKeyframeAtFrame

Internally, every morph weight commit calls upsertMorphKeyframeAtFrame from lib/utils.ts. The function handles both the insert-new and update-existing cases in a single pass: 
export function upsertMorphKeyframeAtFrame(
  clip: AnimationClip,
  morphName: string,
  frame: number,
  weight: number,
): AnimationClip {
  // Pull the existing track for this morph (or start fresh).
  const prevTrack = clip.morphTracks.get(morphName) ?? []

  // Remove any existing keyframe at this exact frame, then add the new one.
  const nextTrack = prevTrack.filter((k) => k.frame !== frame)
  nextTrack.push({ morphName, frame, weight })

  // Keep the track sorted by frame so interpolation is correct.
  nextTrack.sort((a, b) => a.frame - b.frame)

  // Return an updated clip with the new track (shallow clone for React).
  const morphTracks = new Map(clip.morphTracks)
  morphTracks.set(morphName, nextTrack)
  return { ...clip, morphTracks }
}
The returned AnimationClip is then passed to commit(), which records it in the undo history.

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The MorphKeyframe Type

A morph keyframe is the simplest data type in the clip — just a name, a frame, and a weight: 
type MorphKeyframe = {
  /** The morph's PMX-internal name (used to look up the track). */
  morphName: string

  /** Frame number at which this weight snapshot is taken. */
  frame: number

  /** Blend weight: 0.0 = no morph applied, 1.0 = full morph applied. */
  weight: number
}
Unlike BoneKeyframe, there is no interpolation field — morph interpolation is always linear between two adjacent keyframes.

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Viewing Morph Keyframes in the Dopesheet

When the Morph tab is active in the timeline, the dopesheet row shows diamonds for every MorphKeyframe in the selected morph’s track. Morph keyframe diamonds respond to the same interactions as bone keyframe diamonds:
  • Click to select.
  • Drag horizontally to retime (one undo step on release).
  • Arrow keys to nudge by one frame.
  • Delete button or Delete key to remove.
To see all morph tracks simultaneously alongside bone tracks, switch back to the All Rot or All Trans tab — the dopesheet rows for morphs appear below the bone rows when a morph track has at least one keyframe.

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Deleting Morph Keyframes

1

Select the keyframe

Click the diamond on the morph’s dopesheet row at the frame you want to remove.
2

Delete

Click Delete in the Operations section of the Properties Inspector. The keyframe is removed and the change is committed as one undo step.

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