What Created this Windwhield Crack Pattern?

I've had a crack that looked very similar to that from what I assume was a rock from a large dump truck going past me in the opposite direction. I seem to be a real rock magnet, I've had to replace the windshields in the past 3 vehicles from rock impacts. I only made it two weeks in my new 2012 Volt before cracking the windshield, but I was able to have that one repaired.