From 42908537596d8fa603d0233d11e7bbf03aefffd6 Mon Sep 17 00:00:00 2001
From: Hector Sanjuan <code@hector.link>
Date: Mon, 14 Aug 2023 15:17:38 +0200
Subject: [PATCH] rotor-effects: activate effects based on configured flight
 physic realism

---
 src/sfm.h         |  6 +++++-
 src/sfmsimforce.c | 18 +++++++++++++-----
 src/sfmtypes.h    |  5 +++++
 src/simmanage.c   |  1 +
 4 files changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/sfm.h b/src/sfm.h
index c640f60..3966ec0 100644
--- a/src/sfm.h
+++ b/src/sfm.h
@@ -73,7 +73,11 @@ typedef struct {
 	SFMPositionStruct       actual_wind_vector;	/* In meters per Cycle */    
 	unsigned long		wind_flags;
 	SFMBoolean		wind_enabled;
-	/* Callbacks, typical inputs are; realm pointer,
+
+    	/* Realism setting */
+    	SFMFlightPhysicsLevel	flight_physics_level;
+
+        /* Callbacks, typical inputs are; realm pointer,
 	 * model pointer, client data
 	 */
 
diff --git a/src/sfmsimforce.c b/src/sfmsimforce.c
index 749ab25..4ba12f9 100644
--- a/src/sfmsimforce.c
+++ b/src/sfmsimforce.c
@@ -1532,7 +1532,8 @@ int SFMForceApplyArtificial(
 		 * Effect starts at a rotor height of 1.25 rotor diameter.
 		 * http://www.copters.com/aero/ground_effect.html
 		 */
-		if(flags & SFMFlagRotorDiameter)
+		if(flags & SFMFlagRotorDiameter &&
+		    realm->flight_physics_level >= SFM_FLIGHT_PHYSICS_MODERATE)
 		{
 		    // Twin-rotor aircrafts note:
 		    //   - Coaxial are assumed to experience normal IGE since its a single
@@ -1596,6 +1597,7 @@ int SFMForceApplyArtificial(
 		 */
 
 		if (flags & SFMFlagSingleMainRotor && // does not affect twin as they compensate.
+		    realm->flight_physics_level >= SFM_FLIGHT_PHYSICS_REALISTIC &&
 		    !model->landed_state &&
 		    airspeed_rotor_2d > 0
 		    ) {
@@ -1626,12 +1628,17 @@ int SFMForceApplyArtificial(
 		 *
 		 * https://en.wikipedia.org/wiki/Translational_lift
 		 */
+
+		// ETL Thrust penalty
 		// Goes from 1 (full penalty) to 0 when it reaches SFMETLSpeed
 		// Square progression so that it goes a bit slower close to 0.
-		double etl_thrust_coeff = 1 - POW(CLIP(airspeed_rotor_2d / SFMETLSpeed, 0, 1),2);
-		thrust_output = (1 - 0.25 * etl_thrust_coeff) * thrust_output;
-
-		if (!model->landed_state &&
+		if (realm->flight_physics_level >= SFM_FLIGHT_PHYSICS_MODERATE) {
+		    double etl_thrust_coeff = 1 - POW(CLIP(airspeed_rotor_2d / SFMETLSpeed, 0, 1),2);
+		    thrust_output = (1 - 0.25 * etl_thrust_coeff) * thrust_output;
+		}
+		// ETL pitch
+		if (realm->flight_physics_level >= SFM_FLIGHT_PHYSICS_REALISTIC &&
+		    !model->landed_state &&
 		    airspeed_rotor_2d > 0
 		    ) {
 		    // Similar to TF, we add some pitch/bank changes while
@@ -1659,6 +1666,7 @@ int SFMForceApplyArtificial(
 		 */
 
 		if(flags & SFMFlagSingleMainRotor && // does not affect twin rotors
+		   realm->flight_physics_level >= SFM_FLIGHT_PHYSICS_REALISTIC &&
 		   !model->landed_state
 		    ) {
 		    // torque_coeff: 1 at 0-speed, 0 at SFMETLEnd and negative
diff --git a/src/sfmtypes.h b/src/sfmtypes.h
index b4d04e3..27c26a4 100644
--- a/src/sfmtypes.h
+++ b/src/sfmtypes.h
@@ -79,6 +79,11 @@ typedef struct {
 } SFMDirectionStruct;
 
 
+typedef enum {
+	SFM_FLIGHT_PHYSICS_EASY,
+	SFM_FLIGHT_PHYSICS_MODERATE,
+	SFM_FLIGHT_PHYSICS_REALISTIC
+} SFMFlightPhysicsLevel;
 
 
 
diff --git a/src/simmanage.c b/src/simmanage.c
index 47323f5..8a2cb5e 100644
--- a/src/simmanage.c
+++ b/src/simmanage.c
@@ -690,6 +690,7 @@ int SARSimUpdateSceneObjects(
 	    if(scene->realm != NULL)
 	    {
 		scene->realm->wind_enabled = core_ptr->option.wind;
+		scene->realm->flight_physics_level = (SFMFlightPhysicsLevel)(core_ptr->option.flight_physics_level);
 
 		/* Handle by object type */
 		switch(obj_ptr->type)