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metaverseDubai/docs/HOUDINI_PIPELINE.md

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# Houdini Pipeline - Dubai Metaverse
## Overview
This document describes the Houdini to Unreal Engine pipeline for procedural generation in the Dubai Metaverse project.
## Houdini Engine Setup
### Prerequisites
- **Houdini**: Installed on development machine
- **Houdini Engine Plugin**: Installed in Unreal Engine 5.4
- **Compatible Versions**: Check UE5.4 compatibility with Houdini version
### Installation
1. **Install Houdini**: Download and install from SideFX
2. **Install Houdini Engine Plugin**:
- Edit > Plugins
- Search for "Houdini Engine"
- Enable plugin
- Restart editor
3. **Configure Houdini Path**:
- Edit > Project Settings > Plugins > Houdini Engine
- Set Houdini installation path
- Verify connection
---
## Houdini Digital Assets (HDAs)
### What are HDAs?
Houdini Digital Assets are packaged Houdini tools that can be imported into Unreal Engine. They expose parameters that can be adjusted in Unreal without opening Houdini.
### HDA Types for Dubai Metaverse
1. **Building Generator**: Modular building generation
2. **Road Network**: Road generation tool
3. **Terrain Sculpt**: Terrain refinement
---
## Building Generator HDA
### File: building_generator.hda
**Purpose**: Generate modular buildings procedurally
### Parameters
- **Building Type**: Residential, Commercial, Mixed-use
- **Height**: Building height (floors)
- **Width**: Building width
- **Depth**: Building depth
- **Style**: Modern, Traditional, Luxury
- **Details**: Window patterns, balconies, etc.
### Output
- **High-Poly Mesh**: Detailed building geometry
- **Low-Poly Mesh**: Optimized version (optional)
- **UVs**: Unwrapped UVs for texturing
- **Material IDs**: Material assignment IDs
### Workflow
1. **Create HDA in Houdini**:
- Build procedural building generator
- Define parameters
- Package as HDA
2. **Export HDA**:
- Save as `.hda` file
- Place in `houdini/` directory
3. **Import to Unreal**:
- Import HDA via Houdini Engine
- Create HDA instance in level
- Adjust parameters in Unreal
4. **Bake to Static Mesh** (optional):
- Bake HDA output to static mesh
- Enable Nanite if high-poly
- Assign materials
---
## Road Network HDA
### File: road_network.hda
**Purpose**: Generate road network from splines or points
### Parameters
- **Road Width**: Main road width
- **Sidewalk Width**: Sidewalk width
- **Road Material**: Road surface material
- **Lane Count**: Number of lanes
- **Intersection Type**: T-intersection, 4-way, roundabout
### Output
- **Road Mesh**: Road geometry
- **Sidewalk Mesh**: Sidewalk geometry
- **Markings**: Lane markings, crosswalks
- **Intersections**: Road intersections
### Workflow
1. **Create Road Network in Houdini**:
- Input: Splines or points defining road network
- Generate road geometry
- Add intersections
- Package as HDA
2. **Import to Unreal**:
- Import HDA
- Create instance
- Connect to road splines in level
3. **Bake to Static Mesh**:
- Bake road geometry
- Assign materials
- Place in level
---
## Terrain Sculpt HDA
### File: terrain_sculpt.hda
**Purpose**: Refine and sculpt terrain from elevation data
### Parameters
- **Terrain Resolution**: Heightmap resolution
- **Sculpting Tools**: Erosion, smoothing, detail
- **Feature Generation**: Hills, valleys, etc.
### Output
- **Refined Heightmap**: Enhanced terrain heightmap
- **Terrain Mesh**: Terrain geometry (optional)
### Workflow
1. **Import Elevation Data**:
- Import DEM/GeoTIFF to Houdini
- Convert to heightfield
2. **Sculpt Terrain**:
- Apply erosion
- Add details
- Smooth areas
3. **Export**:
- Export refined heightmap
- Import to Unreal
- Generate landscape
---
## Houdini to Unreal Workflow
### Step 1: Create HDA in Houdini
1. **Build Tool**: Create procedural tool in Houdini
2. **Define Parameters**: Expose parameters for adjustment
3. **Test**: Test tool in Houdini
4. **Package**: Package as HDA file
### Step 2: Import to Unreal
1. **Import HDA**: Import via Houdini Engine
2. **Create Instance**: Create HDA instance in level
3. **Adjust Parameters**: Adjust parameters in Unreal
4. **Validate**: Check output quality
### Step 3: Bake (Optional)
1. **Bake to Static Mesh**: Convert HDA output to static mesh
2. **Enable Nanite**: If high-poly, enable Nanite
3. **Assign Materials**: Assign materials
4. **Optimize**: Optimize for performance
---
## HDA Organization
### Folder Structure
```
houdini/
├── building_generator.hda
├── road_network.hda
├── terrain_sculpt.hda
└── assets/
└── [HDA source files]
```
### Naming Convention
- **Format**: `system_name.hda`
- **Examples**:
- `building_generator.hda`
- `road_network.hda`
---
## Best Practices
### HDA Design
1. **Parameter Organization**: Group related parameters
2. **Default Values**: Set sensible defaults
3. **Documentation**: Document parameters and usage
4. **Validation**: Validate input and output
### Performance
1. **Optimization**: Optimize HDA for performance
2. **Baking**: Bake to static meshes when possible
3. **LODs**: Consider LOD generation
4. **Caching**: Use Houdini caching for complex operations
### Workflow
1. **Iterate in Houdini**: Develop and test in Houdini first
2. **Simplify for Unreal**: Simplify if needed for Unreal
3. **Document**: Document HDA usage
4. **Version Control**: Track HDA versions
---
## Troubleshooting
### Common Issues
**Issue**: HDA not importing
- **Solution**: Check Houdini Engine plugin is enabled
- **Solution**: Verify Houdini installation path
- **Solution**: Check Houdini version compatibility
**Issue**: Parameters not working
- **Solution**: Verify parameters are exposed in HDA
- **Solution**: Check parameter types match
**Issue**: Performance issues
- **Solution**: Bake to static meshes
- **Solution**: Optimize HDA operations
- **Solution**: Use caching
---
## Resources
- **Houdini Documentation**: [sidefx.com/docs](https://www.sidefx.com/docs/)
- **Houdini Engine for Unreal**: [sidefx.com/software/engines/unreal](https://www.sidefx.com/software/engines/unreal/)
- **Houdini Learning**: SideFX learning resources
---
**Version**: 1.0
**Last Updated**: [Current Date]