Plane: more places checking for terrain alt

Author: tridge

ArduPlane/ArduPlane.cpp

@@ -859,7 +859,7 @@ bool Plane::set_target_location(const Location &target_loc)
         return false;
     }
     // add home alt if needed
-    if (loc.relative_alt) {
+    if (loc.relative_alt && !loc.terrain_alt) {
         loc.alt += plane.home.alt;
         loc.relative_alt = 0;
     }

ArduPlane/GCS_Mavlink.cpp

@@ -749,7 +749,7 @@ bool GCS_MAVLINK_Plane::handle_guided_request(AP_Mission::Mission_Command &cmd)
 void GCS_MAVLINK_Plane::handle_change_alt_request(AP_Mission::Mission_Command &cmd)
 {
     plane.next_WP_loc.alt = cmd.content.location.alt;
-    if (cmd.content.location.relative_alt) {
+    if (cmd.content.location.relative_alt && !cmd.content.location.terrain_alt) {
         plane.next_WP_loc.alt += plane.home.alt;
     }
     plane.next_WP_loc.relative_alt = false;

ArduPlane/mode_guided.cpp

@@ -109,7 +109,7 @@ void ModeGuided::navigate()
 bool ModeGuided::handle_guided_request(Location target_loc)
 {
     // add home alt if needed
-    if (target_loc.relative_alt) {
+    if (target_loc.relative_alt && !target_loc.terrain_alt) {
         target_loc.alt += plane.home.alt;
         target_loc.relative_alt = 0;
     }