MPL - Motion Programming Language

MPL is a domain-specific language that revolutionizes 3D motion and animation through human-readable, semantic syntax. Designed to bridge the gap between natural language and 3D movement, MPL transforms complex mathematical representations into intuitive, code-like commands that both humans and AI systems can easily understand and generate.

Current Implementation: MMD (MikuMikuDance) format support with plans for broader 3D animation ecosystems.

Gallery and playground

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Why MPL?

🎯 Human-Centric Design

• Semantic commands: Intuitive, readable syntax for complex 3D movements
• Natural language alignment: Bridge human intent and 3D mathematics
• Built-in safety: Anatomically-aware constraints prevent impossible poses

🤖 AI & Machine Learning Ready

• LLM-friendly syntax: Structured grammar for language models
• Training-optimized: Semantic tokens for AI motion synthesis
• Compositional intelligence: Modular components for pattern learning
• Cross-modal potential: Text-to-motion and motion-to-text transformations

🔧 Developer Benefits

• Composable architecture: Reusable animation building blocks
• Version control friendly: Text-based format for development workflows
• Extensible framework: Domain-agnostic design for future formats

Syntax

Pose Definitions

@pose kick_left {
    leg_l bend forward 30;
    knee_l bend backward 0;
    leg_r bend backward 20;
    knee_r bend backward 15;
}

@pose kick_right {
    leg_r bend forward 30;
    knee_r bend backward 0;
    leg_l bend backward 20;
    knee_l bend backward 15;
}

Animation Sequences

@animation walk {
    0: kick_left;
    0.3: kick_right;
    0.6: kick_left;
    0.9: kick_right;
}

Main Execution

main {
    walk;
}

Bone Commands

Format: bone action direction amount; or bone reset;

Actions: bend, turn, sway, move, reset
Directions: forward, backward, left, right, up, down

Compound Statements

Multiple actions for the same bone can be combined on a single line using commas:

head turn left 30, bend forward 20, sway right 15;
arm raise up 45, rotate right 15;
neck reset;

Supported Bones

Body Core: base, center, upper_body, waist, neck, head
Arms: shoulder_l/r, arm_l/r, arm_twist_l/r, elbow_l/r, wrist_l/r, wrist_twist_l/r
Legs: leg_l/r, knee_l/r, ankle_l/r, toe_l/r
Fingers:

• Individual joints: thumb_0/1/2_l/r, index_0/1/2_l/r, middle_0/1/2_l/r, ring_0/1/2_l/r, pinky_0/1/2_l/r
• Grouped shortcuts: thumb_l/r, index_l/r, middle_l/r, ring_l/r, pinky_l/r

Finger Control Shortcuts

Grouped finger shortcuts automatically expand to individual joint movements with realistic ratios:

// Using grouped shortcuts (recommended for most cases)
index_l bend forward 30;    // Expands to: index_0_l bend forward 30, index_1_l bend forward 27, index_2_l bend forward 20
middle_l bend forward 25;   // Expands to: middle_0_l bend forward 25, middle_1_l bend forward 23, middle_2_l bend forward 16
thumb_l bend forward 20;    // Expands to: thumb_0_l bend forward 20, thumb_1_l bend forward 17

// Using individual joints (for precise control)
index_0_l bend forward 30;
index_1_l bend forward 25;
index_2_l bend forward 15;

Finger Bending Ratios:

• Index/Middle: 100% → 90% → 65%
• Ring: 100% → 88% → 60%
• Pinky: 100% → 85% → 55%
• Thumb: 100% → 85%

Both approaches can be mixed in the same pose.

🚀 Command Line Tool

The MPL compiler is available as a command-line tool (mpl.exe in cmd/ directory) or build from source with cargo build --release.

Usage:

• Compile MPL to VMD: mpl -c input.mpl -o output.vmd
• Reverse compile VMD/VPD to MPL: mpl -r input.vmd -o output.mpl

📄 License

GPL-3.0 License - see LICENSE for details.