Terraform terrain on impact

Anyone know of a way to lets say lower or raise terrain when an object hits it? Example, a large rock falling and creating a dent in the terrain?

 

You could try to use SetPixel() on terrain heightmap. I think it should work.

 

There are two problems here, so break them apart and tackle them one at a time.

Problem 1: converting the position (and size) of the rock in world space coordinates into a heightmap address on the terrain. This has to take into account the position of the Terrain object, the dimensions of the terrain, etc. It's quite a few steps but Unity's API makes it very easy. I have some examples of interoperating between world space and terrain heightmap space in my Makegeo project, which contains a TerrainRampMaker sub-project.

MakeGeo is presently hosted at these locations:

https://bitbucket.org/kurtdekker/makegeo

https://github.com/kurtdekker/makegeo

https://gitlab.com/kurtdekker/makegeo

Problem 2 is actually deciding how much to dent the rock, and iterating the heightmap array information from the TerrainData that the Terrain uses, and then writing it back. The above example also covers that step as it modifies the ground to create a smooth Terrain ramp.