Stone Devlog: Hertz So Good

To kick off the refinement of the knapping system, I decided to hit the books again. Watching videos on flint knapping had become a bit of a pastime for me and I thought I had a handle on how the process went. However, it wasn't until recently that I dug into some more academic resources and really wrapped my head around it.

Not long after lamenting that simple geometric primitives were not going to be sufficient to create a convincing knapping system, I learned that real-life knapping does (somewhat) boil down to subtracting a geometric primitive. Introducing the Hertzian Cone:

The short of it is, when you strike certain brittle materials (like flint), the force propagates from the point of impact through the material in a distinctive cone. The portion within the cone is essentially blown out of the object when it is struck. Sources have been a little light on specifics, but apparently the angle of the cone is typically about 100 degrees, though it can vary and evidently can be controlled to an extent.

From wildernesscollege.com

This almost seems too good to be true. You can't just tap a big rock right in the middle and extract a perfect cone from it, so there is certainly a bit more to the physics of it. However, the basic principle of real-life knapping is striking along an edge at an angle such that the cone catches a small sliver of the object.

Also from wildernesscollege.com

It was fortunate that the cone was one of the SDFs I implemented in my bid to stall for time a few months back. It took some doing to properly transform the cone to the rotation of the "stone", but once I did, it started coming together. At first, I wasn't entirely convinced, but it quickly grew on me as I continued to learn about real flint knapping and applied the principles while using my system. Next time we will take a look at the current state of cone-y knapping. Stay tuned.