ishot

an array specifying the directions rays are to be traced from the shot points listed in the arrays xshot and zshot; the following code is used:
(1) 0 - no rays are traced
(2) -1 - rays are traced to the left only
(3) 1 - rays are traced to the right only
(4) 2 - rays are traced to the left and right
(default: 0)