Simplify umbra calculation
Simplify umbra calculation

Reuse pre-computed values

Change-Id: Ia7725be0ec3ac58af477fcb8de375f5faa05abf4

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base