Basically the same basics as programming enemy AI. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwjWvJ6MkebLAhWGw4MKHTEIACgQtwIIMDAC&url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DkQ8i9Sxw33g&usg=AFQjCNFBcbcWGBGCqYReI5UUV1gwojehtg&sig2=mwqFaI_e9kK5qwiuygzEEQ