Shader Recompilation Delays Water Visibility in Houdini Engine > 20.0.625 with Unreal 5.3

[chickenmi]

Issue Summary

When using Houdini Engine versions above 20.0.625 with Unreal Engine 5.3, importing a landscape with multiple paint layers and adding a water body actor sometimes triggers unexpected shader recompilation. This causes the water body to remain invisible until the process completes. The issue is intermittent but consistently reproducible when landscape paint layers are modified and re-imported. This behavior is not observed in Houdini Engine version 20.0.625 or earlier.

Steps to Reproduce

1. Setup:

   • Use Houdini Engine version above 20.0.625.
   • Use Unreal Engine 5.3.

2. Import Landscape:

   • Create a landscape in Houdini with multiple paint layers.
   • Import the landscape into Unreal Engine 5.3.

3. Add Water Body:

   • Place a water body actor (e.g., lake, river) onto the imported landscape.

4. Modify Layers:

   • Change one or more paint layers on the landscape and re-import.

5. Observe Behavior:

   • Notice that shader recompilation is intermittently triggered after modifying layers.
   • The water body remains invisible until shader compilation completes.

Expected Behavior

The water body should appear immediately upon placement or after layer modifications without triggering shader recompilation.

Actual Behavior

Shader recompilation occurs intermittently, particularly after changing and re-importing paint layers. This causes delays, as the water body remains invisible until recompilation completes. The issue is particularly disruptive when iterating on landscapes, as it requires waiting for recompilation after each change.

Additional Information

• This issue is absent when using Houdini Engine version 20.0.625 or earlier with Unreal Engine 5.3.
• The problem persists across the latest versions of Houdini Engine above 20.0.625.
• The issue does not occur every time but can be reproduced consistently by modifying landscape layers and re-importing.

Request for Assistance

• Are there known changes in Houdini Engine versions above 20.0.625 that might affect shader compilation in Unreal Engine 5.3?
• Could the interaction between landscape paint layers and water body actors be influencing shader behavior in newer versions?
• Are there any recommended workflows or settings to mitigate this intermittent shader recompilation?

Environment Details

• Houdini Engine Version: 20.0.625 and above
• Unreal Engine Version: 5.3
• Operating System: Windows 11

Note

This issue is particularly problematic during iterative development, as it requires waiting for shader recompilation after every landscape change, which significantly slows down the workflow. Any assistance in identifying the root cause or potential solutions would be appreciated.