Detail this asset from Unity Asset Store: Original Link
This is a paid asset, but now you can download Digger – Terrain Caves & Overhangs Free.
Digger – Terrain Caves & Overhangs v2.2
Digger – Terrain Caves & Overhangs v2.1
Digger – Terrain Caves & Overhangs v1.9
Digger is a simple yet powerful tool to create natural caves and overhangs in your Unity terrains directly from the Unity editor.
Unleash the full power of Digger with Unity 2019.3! Digger 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 is recommended to get the best out of Digger.
NEW: MicroSplat (requires MicroSplat Digger module) and HDRP support!
Demo (of PRO version) | Doc | Discord | PRO version
Note: if you buy Digger you can get Digger PRO for a lower price.
More and more AAA games add gentle overhangs and caves to their environment to make it more realistic, more interesting and more diversified.
A common way to do this is to create 3D models with an external modeling tool, and then place them manually over the terrain and blend them with it. This is tedious, unpractical and inefficient unless you have an army of 3D artists and level designers… and even in that case, you’d probably want them to focus on more valuable work.
This is where Digger comes to action. No more external tool required, no more loss of time, no more headache. It lets you create caves and overhangs on your terrain directly within the scene view, in a few clicks.
It 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 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.
➤ With Digger PRO only: dig in real-time at runtime.
However, you won’t be able to:
➤ Generate caves procedurally.
If you need this feature, you should get a full voxel-based terrain solution, like Ultimate Terrains.
➤ 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
➤ With Unity 2019.3 or above: full NavMesh support
➤ Compatible with Gaia
➤ Only with Digger PRO: dig in real-time, at runtime.
➤ Only with Digger PRO: update NavMesh at runtime.
➤ 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+)
➤ Supports High Definition Render Pipeline (aka. HDRP) terrain shader (Unity 2019.3+)
➤ 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. It also requires Burst and Mathematics packages.
➤ Doesn’t work properly with terrain lightmapping
About Unity 2019.3
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 is a perfect companion of this new feature.
Thanks to this new way to cut holes in the terrain surface, Digger has better performance, is more robust, works out of the box with NavMesh and works with Physics.Raycast (no need to use DiggerPhysics anymore).