This is a paid asset, but now you can download NavMesh Generator for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
NavMesh Generator v1.1d
Introduction
When you work with terrain, maybe you need to design some areas to be walkable, while others are not.
At this time, you need to define and generate corresponding models to bake navmesh.
To avoid the need to manually build these models, or export the terrain to external software for editing.
NavMesh Generator can help you to quickly define the walkable area in unity and bake out the corresponding navmesh.
Note:
The sample house model does not exist in Asset.(Just for demonstration)
Feature:
– Generate mesh according to what you mask and paint.
– You can modify and restore the terrain back and forth.
– Auto split to multiple models for maximum accuracy.
– Very easy use.
– Support terrain and model objects.