can we rename "constains_terrain_relative" to "contains_terrain_alt"? No big deal of course but "terrain_alt" is what we use in Copter so it's more likely to show up in searches.
can we rename "constains_terrain_relative" to "contains_terrain_alt"? No big deal of course but "terrain_alt" is what we use in Copter so it's more likely to show up in searches.
If SITL is not receiving any sitl rc input (so _sitl_rc_in.recv(...) is allways returns -1 then the bind-values code would never be crossed so the RC input values would remain at their initialisation values rather than honouring the SIM_RC_FAIL setting which says they should go to bind values (notably throttle-to-950)
The squares surrounding the current location were only checked when we went to send a terrain request. This means it was possible that:
- the number of pending requests could go to zero
- prearm checks would pass
- vehicle arm is attempted by the user (or a script, or ....)
- the code would call AP_Terrain::send_requests which would create more pending requests
- the arming sequence would fail
It's also possible for the arming to succeed, and then we're flying in violation of the intended prearm checks.
Doing things in the update function has the additional advantage of making things more efficient as we can push out terrain requests more often.
looking at pending is insufficient as we may have more mission items to check to see if they need other pieces of terrain. That is, terr_pending can go to zero momentarily and then go back to a non-zero number as Terrain's update method checks the mission and rally libraries for more terrain requirements.
Without this patch the prearm checks can momentarily pass, allowing the vehicle to arm. The vehicle could hit a terrain failsafe later if it doesn't manage to get the data while in flight.
Before this patch we would display PreArm: even if the checks were being performed as part of the arming sequence.
This lets us distinguish betwee checks failing because the user is trying to arm the vehicle and when the prearms are running while disarmed (or triggered via GCS)
The position vector passed to update method is relative to home and the precland device origin height is also relative to home. Hence, we
can set the height of precland origin separately in a 3d vec containing its position relative to home
