AP_WindVane: add SITL driver

libraries/AP_WindVane/AP_WindVane.cpp

@@ -23,6 +23,9 @@
 #if CONFIG_HAL_BOARD == HAL_BOARD_PX4 || CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN
 #include <board_config.h>
 #endif
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+#include <SITL/SITL.h>
+#endif
 
 extern const AP_HAL::HAL& hal;
 
@@ -200,6 +203,26 @@ float AP_WindVane::read_PWM_bearing()
     return wrap_PI(bearing);
 }
 
+// read the apparent wind direction in radians from SITL
+float AP_WindVane::read_direction_SITL()
+{
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+    // temporarily store true speed and direction for easy access
+    const float wind_speed = AP::sitl()->wind_speed_active;
+    const float wind_dir_rad = radians(AP::sitl()->wind_direction_active);
+
+    // convert true wind speed and direction into a 2D vector
+    Vector2f wind_vector_ef(sinf(wind_dir_rad) * wind_speed, cosf(wind_dir_rad) * wind_speed);
+
+    // add vehicle speed to get apparent wind vector
+    wind_vector_ef.x += AP::sitl()->state.speedE;
+    wind_vector_ef.y += AP::sitl()->state.speedN;
+
+    return wrap_PI(atan2f(wind_vector_ef.x, wind_vector_ef.y) - AP::ahrs().yaw);
+#else
+    return 0.0f;
+#endif
+}
 // Calculate the apparent wind direction in radians, the wind comes from this direction, 0 = head to wind
 void AP_WindVane::update_apparent_wind_direction()
 {
@@ -219,6 +242,11 @@ void AP_WindVane::update_apparent_wind_direction()
         case WindVaneType::WINDVANE_ANALOG_PIN:
             apparent_angle_in = read_analog();
             break;
+        case WindVaneType::WINDVANE_SITL:
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+            apparent_angle_in = read_direction_SITL();
+#endif
+            break;
     }
 
     // apply low pass filter if enabled

libraries/AP_WindVane/AP_WindVane.h

@@ -28,6 +28,7 @@ public:
         WINDVANE_HOME_HEADING = 1,
         WINDVANE_PWM_PIN    = 2,
         WINDVANE_ANALOG_PIN = 3,
+        WINDVANE_SITL       = 10
     };
 
     AP_WindVane();
@@ -67,6 +68,9 @@ private:
     // read the bearing value from a PWM value on a RC channel - returns radians
     float read_PWM_bearing();
 
+    // read the apparent wind direction in radians from SITL
+    float read_direction_SITL();
+
     // update apparent wind direction
     void update_apparent_wind_direction();