Tools: add follow-copter.sh for SITL

Another copy of this script -  but this one doesn't need Morse or AirSim

libraries/SITL/examples/follow-copter.sh

@@ -0,0 +1,75 @@
+#!/bin/bash
+
+# Usage - From ardupilot root directory, run - libraries/SITL/examples/follow-copter.sh $GCS_IP
+# $GCS_IP is the IP address of the system running the GCs, by default is 127.0.0.1
+# mavproxy --master mcast:
+
+# Kill all SITL binaries when exiting
+trap "killall -9 arducopter" SIGINT SIGTERM EXIT
+
+# assume we start the script from the root directory
+ROOTDIR=$PWD
+COPTER=$ROOTDIR/build/sitl/bin/arducopter
+
+# Set GCS_IP address
+if [ -z $1 ]; then
+    GCS_IP="127.0.0.1"
+else
+    GCS_IP=$1
+fi
+
+# Check if Platform is Native Linux, WSL or Cygwin
+# Needed for correct multicast addressing
+unameOut="$(uname -s)"
+
+if [ "$(expr substr $unameOut 1 5)" == "Linux" ]; then
+    # Check for WSL
+    if grep -q Microsoft /proc/version; then
+        MCAST_IP_PORT="127.0.0.1:14550"
+
+    # Native Linux
+    else
+        MCAST_IP_PORT=""                    # Use default IP, port
+    fi
+
+elif [ "$(expr substr $unameOut 1 6)" == "CYGWIN" ]; then
+    MCAST_IP_PORT="0.0.0.0:14550"
+fi
+
+BASE_DEFAULTS="$ROOTDIR/Tools/autotest/default_params/copter.parm"
+
+[ -x "$COPTER" ] || {
+	./waf configure --board sitl
+	./waf copter
+}
+
+# start up main copter in the current directory
+$COPTER --model quad --uartA udpclient:$GCS_IP --uartC mcast:$MCAST_IP_PORT --defaults $BASE_DEFAULTS &
+
+# Set number of extra copters to be simulated, change this for increasing the count
+NCOPTERS="1"
+
+
+# now start another copter to follow the first, using
+# a separate directory to keep the eeprom.bin and logs separate
+for i in $(seq $NCOPTERS); do
+    echo "Starting copter $i"
+    mkdir -p copter$i
+
+    SYSID=$(expr $i + 1)
+    FOLL_SYSID=$(expr $SYSID - 1)
+
+    # create default parameter file for the follower
+    cat <<EOF > copter$i/follow.parm
+SYSID_THISMAV $SYSID
+FOLL_ENABLE 1
+FOLL_OFS_X -5
+FOLL_OFS_TYPE 1
+FOLL_SYSID $FOLL_SYSID
+FOLL_DIST_MAX 1000
+EOF
+    pushd copter$i
+    $COPTER --model quad --uartA tcp:0 --uartC mcast:$MCAST_IP_PORT --instance $i --defaults $BASE_DEFAULTS,follow.parm &
+    popd
+done
+wait