**3D Model Viewer - Your Portable 3D File Browser**

🎨 A professional 3D model viewing app designed for 3D printing enthusiasts, engineers, and designers. Easily view, rotate, and analyze your 3D model files on your phone!

### ✨ Core Features

**📂 Powerful File Format Support**
• STL Format - Perfect support for ASCII and Binary formats
• OBJ Format - Supports vertices, normals, and face data
• ZIP Archives - Batch import multiple models
• RAR Archives - Auto-extract and load models
• 7Z Archives - Support for high compression formats
• Simultaneous loading and management of multiple files

**🎯 Intuitive 3D Viewing Experience**
• Real-time 3D Rendering - Smooth rendering based on OpenGL ES 2.0
• Wireframe Mode - Clearly display model topology structure
• Reference Grid - Helps understand model spatial position and scale
• Professional Lighting Effects - Better observe model details
• Auto-scaling and Centering - Models automatically fit the screen

**👆 Flexible Touch Controls**
• Single-finger Rotation - Drag in center area for 360° free model rotation
• Two-finger Zoom - Pinch/spread gestures for precise size control (0.1x-10x)
• Edge Panning - Drag at screen edges to move model up/down/left/right
• Double-tap Reset - Quick return to initial view
• Auto-rotation - Model auto-displays, switches to manual control after touch

**📦 Multi-model Management**
• Load multiple 3D model files simultaneously
• Independently control each model's show/hide state
• Display model name and vertex count information
• Batch management, one-click show/hide all models

### 🎯 Use Cases

**3D Printing Enthusiasts**
• Quickly preview STL print files
• Check model structure and topology
• Confirm model is complete and defect-free

**Engineers and Designers**
• View CAD-exported models on mobile
• Present 3D designs to clients on-site
• Quickly check model dimensions and structure

**3D Modeling Learners**
• Learn 3D model structure
• Observe professional model topology
• Understand 3D geometry principles

**Educators**
• Display 3D models in classroom
• Demonstrate solid geometry teaching
• Intuitively present 3D concepts

### 💡 How to Use

**1. Open File**
- Click "+" button to select file from phone
- Support opening directly from file manager
- Support batch selection of multiple files

**2. View Model**
- Single-finger drag to rotate and view all angles
- Two-finger pinch/spread to zoom model
- Drag at screen edges to pan model position

**3. Switch Display Modes**
- Click wireframe button to toggle wireframe mode
- Click grid button to show/hide reference grid
- View more structural details

**4. Manage Multiple Models**
- Click list button to view all loaded models
- Use switches to control each model's show/hide

**5. Reset View**
- Double-tap screen to quickly reset to initial view
- Or click settings to restore default settings

### ⚡ Performance Features

• Lightweight app, installation package under 10MB
• Smooth 60FPS rendering performance
• Supports large models (millions of triangles)
• Low memory usage, no lag
• Fast loading, ready to use

### 🔐 Privacy & Permissions

• Only requires file read permission
• Does not collect any personal information
• No network connection required
• Completely offline operation
• Your files remain entirely on local device

### 📊 Technical Specifications

• Minimum System Requirements: Android 7.0 (API 24)
• Recommended System: Android 10 and above