Good news, I’ve managed to get performance good enough that iPhone 6 or better should be able to handle shadows for my game. Bad news, a weird ring effect.
My setup is a directional light parented by the camera, basically shining down onto a spherical scene. At certain rotations the shadows appear fine (not many), then there is a weird rippling effect and the whole world goes dark. The shadow distance of the light is automatically setup using the distance of the camera to the player - but the shadows either don’t work or work at any of the zoom levels.
I’ve played with the shadowBias but it appears to make no difference. I don’t no what normalOffset is - but it didn’t help either from what I can tell.