From 05a0205c21f69251d311df24b6378c3fb1cf1d84 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Mon, 15 Feb 2021 13:51:06 +1100
Subject: [PATCH] SITL: change to use terrain singleton

---
 libraries/SITL/SIM_Aircraft.cpp | 9 ++++++---
 libraries/SITL/SIM_Aircraft.h   | 2 --
 libraries/SITL/SIM_Ship.cpp     | 8 +-------
 3 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/libraries/SITL/SIM_Aircraft.cpp b/libraries/SITL/SIM_Aircraft.cpp
index 22d1374665..d1428dc222 100644
--- a/libraries/SITL/SIM_Aircraft.cpp
+++ b/libraries/SITL/SIM_Aircraft.cpp
@@ -33,6 +33,7 @@
 #include <AP_Logger/AP_Logger.h>
 #include <AP_Param/AP_Param.h>
 #include <AP_Declination/AP_Declination.h>
+#include <AP_Terrain/AP_Terrain.h>
 
 using namespace SITL;
 
@@ -63,8 +64,6 @@ Aircraft::Aircraft(const char *frame_str) :
         sitl->ahrs_rotation_inv = sitl->ahrs_rotation.transposed();
     }
 
-    terrain = AP::terrain();
-
     // init rangefinder array to -1 to signify no data
     for (uint8_t i = 0; i < RANGEFINDER_MAX_INSTANCES; i++){
         rangefinder_m[i] = -1.0f;
@@ -94,14 +93,18 @@ void Aircraft::set_start_location(const Location &start_loc, const float start_y
 */
 float Aircraft::ground_height_difference() const
 {
+#if AP_TERRAIN_AVAILABLE
+    AP_Terrain *terrain = AP::terrain();
     float h1, h2;
     if (sitl &&
-        sitl->terrain_enable && terrain &&
+        terrain != nullptr &&
+        sitl->terrain_enable &&
         terrain->height_amsl(home, h1, false) &&
         terrain->height_amsl(location, h2, false)) {
         h2 += local_ground_level;
         return h2 - h1;
     }
+#endif
     return local_ground_level;
 }
 
diff --git a/libraries/SITL/SIM_Aircraft.h b/libraries/SITL/SIM_Aircraft.h
index aedac06334..62503f5c3d 100644
--- a/libraries/SITL/SIM_Aircraft.h
+++ b/libraries/SITL/SIM_Aircraft.h
@@ -22,7 +22,6 @@
 
 #include "SITL.h"
 #include "SITL_Input.h"
-#include <AP_Terrain/AP_Terrain.h>
 #include "SIM_Sprayer.h"
 #include "SIM_Gripper_Servo.h"
 #include "SIM_Gripper_EPM.h"
@@ -243,7 +242,6 @@ protected:
 
     bool use_smoothing;
 
-    AP_Terrain *terrain;
     float ground_height_difference() const;
 
     virtual bool on_ground() const;
diff --git a/libraries/SITL/SIM_Ship.cpp b/libraries/SITL/SIM_Ship.cpp
index 5032603442..3584f7f06d 100644
--- a/libraries/SITL/SIM_Ship.cpp
+++ b/libraries/SITL/SIM_Ship.cpp
@@ -174,21 +174,15 @@ void ShipSim::send_report(void)
     Location loc = home;
     loc.offset_double(ship.position.x, ship.position.y);
 
-    int32_t alt;
-    bool have_alt = false;
+    int32_t alt = home.alt;  // assume home altitude
 
 #if AP_TERRAIN_AVAILABLE
     auto terrain = AP::terrain();
     float height;
     if (terrain != nullptr && terrain->enabled() && terrain->height_amsl(loc, height, true)) {
         alt = height * 1000;
-        have_alt = true;
     }
 #endif
-    if (!have_alt) {
-        // assume home altitude
-        alt = home.alt;
-    }
 
     Vector2f vel(ship.speed, 0);
     vel.rotate(radians(ship.heading_deg));