This is a paid asset, but now you can download Digger PRO Free.
Detail this asset from Unity Store: Original Link
Digger PRO v3.0 (Latest version)
Digger PRO v2.4
Digger PRO is a simple yet powerful tool to create natural caves and overhangs in your Unity terrains directly from the Unity editor or from your game. It actually turns your standard terrains into fully destructible terrains.
Digger PRO has all Digger features + real-time / in-game editing support.
Unleash the full power of Digger PRO with Unity 2019.3 (or more recent)! Digger PRO now uses the latest Unity features to cut holes in terrain surface and is even more powerful, robust and performant than ever. From now on, Unity 2019.3 (or more recent) is recommended to get the best out of Digger PRO.
Demo | Doc | Discord | Lite version (no realtime support)
Digger PRO will make you feel like you have a voxel terrain in your hands, without the downsides. It actually keeps the new, fast and reliable Unity’s terrain system and creates seamless cave/overhangs meshes just where you need. Internally, Digger uses voxels and Marching Cubes to create meshes, but instead of replacing the entire terrain with a voxel terrain, it creates a mix of them and gives you the best of both worlds.
With this tool, you will be able to:
➤ Dig in real-time, at runtime.
➤ Update NavMesh at runtime (only with Unity 2019.3 or more recent).
➤ Persist and load at runtime.
➤ Dig in your Unity terrain just like if it was a smooth voxel terrain.
➤ Create overhangs (the opposite of digging).
➤ Apply different textures on the overhangs, in the caves, etc.
However, you won’t be able to:
➤ Generate entire voxel terrains procedurally.
If you need this feature, you should get a full voxel-based terrain solution, like Ultimate Terrains.
➤ Realtime editing support powered by Unity’s JobSystem and Burst.
➤ NEW: async editing at runtime to avoid FPS drops.
➤ NavMesh update at runtime (2019.3+).
➤ Easy to setup (as long as you read setup instructions)
➤ Dig/add mater on terrain
➤ Paint textures on cave meshes
➤ Automatic collision solver
➤ Automatic LOD groups creation
➤ Multi-terrains support
➤ Compatible with Gaia
➤ Bonus: adds triplanar mapping to built-in terrain shaders
➤ Supports standard terrain shader
➤ Supports Lightweight Render Pipeline (aka. LWRP) terrain shader (Unity 2019.2+)
➤ Supports Universal Render Pipeline (aka. URP) terrain shader (Unity 2019.3.14+)
➤ Supports High Definition Render Pipeline 10.2.0 (aka. HDRP) terrain shader (Unity 2020.1+)
➤ NEW: MicroSplat support (requires MicroSplat Digger module)
➤ Supports CTS, but without the possibility to change textures of meshes. Texture can only be the same as terrain texture above. CTS+LWRP and CTS+HDRP are currently not supported.
➤ Full undo/redo support in editor
➤ Lets you set higher resolution for Digger generated meshes
➤ ‘Sync & Refresh’ button to recompute everything (useful if terrain textures or terrain heights changed)
➤ ‘Clear’ button to remove all modifications made with the tool
➤ Remove grass and details automatically
➤ Persists modifications on the fly
Digger requires Unity 2018.4 or a more recent version. Unity 2019.3+ is strongly recommended. It also requires Burst and Mathematics packages.
➤ Doesn’t work properly with terrain lightmapping
About Unity 2019.3 and more recent versions
Unity 2019.3 comes with a new feature allowing to cleanly cut holes in the terrain surface. However, it does not create cave meshes for you. This is why Digger PRO is a perfect companion of this new feature.
Thanks to this new way to cut holes in the terrain surface, Digger PRO has better performance, is more robust, works out of the box with NavMesh and works with Physics.Raycast (no need to use DiggerPhysics anymore).