GetRandPixelDataPos(<-part <-pixelState <-sandDef)
For a specified part, returns the vector world position of a random location that contains a part pixel in the specified pixelState and that is over the specified sandDef. The sandDef can be -1 to ignore the sand type. The pixelState should be one of: 0 = NONE, 1 = ONBOARD, 2 = INROUTE, 3 = DEAD