Example #1
0
        /// <summary>
        /// Integration step function for Verlet integration
        /// </summary>
        /// <param name="state">Position+Velocity of the current time step</param>
        /// <param name="accelerationFunc">Functor that returns the acceleration for a given Position+Velocity</param>
        /// <param name="dt">Time step interval</param>
        /// <param name="accel">Stores the value of the accelerationFunc at the current time step</param>
        /// <returns></returns>
        private static SimulationState VerletStep(SimulationState state, Func <Vector3d, Vector3d, Vector3d> accelerationFunc, double dt, out Vector3d accel)
        {
            Profiler.Start("accelerationFunc outside");
            accel = accelerationFunc(state.position, state.velocity);
            Profiler.Stop("accelerationFunc outside");

            Vector3d prevPos = state.position - dt * state.velocity;

            SimulationState nextState;

            nextState.position = 2.0 * state.position - prevPos + accel * (dt * dt);
            nextState.velocity = (nextState.position - state.position) / dt;

            return(nextState);
        }
Example #2
0
        internal void UpdateVesselMass()
        {
            Profiler.Start("AeroModel.UpdateVesselMass");
            // mass_ = vessel_.totalMass;       // this kills performance on vessel load, so we don't do that anymore

            mass_ = 0d;
            foreach (Part part in Trajectories.AttachedVessel.Parts)
            {
                if (part.physicalSignificance == Part.PhysicalSignificance.NONE)
                {
                    continue;
                }

                float partMass = part.mass + part.GetResourceMass() + part.GetPhysicslessChildMass();
                mass_ += partMass;
            }
            Profiler.Stop("AeroModel.UpdateVesselMass");
        }
        private IEnumerable <bool> AddPatch(VesselState startingState)
        {
            if (null == AttachedVessel.patchedConicSolver)
            {
                AttachedVessel.AttachPatchedConicsSolver();
            }

            CelestialBody body = startingState.ReferenceBody;

            Patch patch = new Patch
            {
                StartingState = startingState,
                IsAtmospheric = false,
                SpaceOrbit    = startingState.StockPatch ?? CreateOrbitFromState(startingState)
            };

            patch.EndTime = patch.StartingState.Time + patch.SpaceOrbit.period;

            // the flight plan does not always contain the first patches (before the first maneuver node),
            // so we populate it with the current orbit and associated encounters etc.
            List <Orbit> flightPlan = new List <Orbit>();

            for (Orbit orbit = AttachedVessel.orbit; orbit != null && orbit.activePatch; orbit = orbit.nextPatch)
            {
                if (AttachedVessel.patchedConicSolver.flightPlan.Contains(orbit))
                {
                    break;
                }
                flightPlan.Add(orbit);
            }

            foreach (Orbit orbit in AttachedVessel.patchedConicSolver.flightPlan)
            {
                flightPlan.Add(orbit);
            }


            Orbit nextPatch = null;

            if (startingState.StockPatch == null)
            {
                nextPatch = patch.SpaceOrbit.nextPatch;
            }
            else
            {
                int planIdx = flightPlan.IndexOf(startingState.StockPatch);
                if (planIdx >= 0 && planIdx < flightPlan.Count - 1)
                {
                    nextPatch = flightPlan[planIdx + 1];
                }
            }

            if (nextPatch != null)
            {
                patch.EndTime = nextPatch.StartUT;
            }

            double maxAtmosphereAltitude = RealMaxAtmosphereAltitude(body);

            if (!body.atmosphere)
            {
                maxAtmosphereAltitude = body.pqsController.mapMaxHeight;
            }

            double minAltitude = patch.SpaceOrbit.PeA;

            if (patch.SpaceOrbit.timeToPe < 0 || patch.EndTime < startingState.Time + patch.SpaceOrbit.timeToPe)
            {
                minAltitude = Math.Min(
                    patch.SpaceOrbit.getRelativePositionAtUT(patch.EndTime).magnitude,
                    patch.SpaceOrbit.getRelativePositionAtUT(patch.StartingState.Time + 1.0).magnitude
                    ) - body.Radius;
            }

            if (minAltitude < maxAtmosphereAltitude)
            {
                double entryTime;
                if (startingState.Position.magnitude <= body.Radius + maxAtmosphereAltitude)
                {
                    // whole orbit is inside the atmosphere
                    entryTime = startingState.Time;
                }
                else
                {
                    entryTime = FindOrbitBodyIntersection(
                        patch.SpaceOrbit,
                        startingState.Time, startingState.Time + patch.SpaceOrbit.timeToPe,
                        body.Radius + maxAtmosphereAltitude);
                }

                if (entryTime > startingState.Time + 0.1 || !body.atmosphere)
                {
                    if (body.atmosphere)
                    {
                        // add the space patch before atmospheric entry

                        patch.EndTime = entryTime;
                        patchesBackBuffer_.Add(patch);
                        AddPatch_outState = new VesselState
                        {
                            Position      = patch.SpaceOrbit.getRelativePositionAtUT(entryTime).SwapYZ(),
                            ReferenceBody = body,
                            Time          = entryTime,
                            Velocity      = patch.SpaceOrbit.getOrbitalVelocityAtUT(entryTime).SwapYZ()
                        };
                    }
                    else
                    {
                        // the body has no atmosphere, so what we actually computed is the entry
                        // inside the "ground sphere" (defined by the maximal ground altitude)
                        // now we iterate until the inner ground sphere (minimal altitude), and
                        // check if we hit the ground along the way
                        double groundRangeExit = FindOrbitBodyIntersection(
                            patch.SpaceOrbit,
                            startingState.Time, startingState.Time + patch.SpaceOrbit.timeToPe,
                            body.Radius - maxAtmosphereAltitude);

                        if (groundRangeExit <= entryTime)
                        {
                            groundRangeExit = startingState.Time + patch.SpaceOrbit.timeToPe;
                        }

                        double iterationSize = (groundRangeExit - entryTime) / 100.0;
                        double t;
                        bool   groundImpact = false;
                        for (t = entryTime; t < groundRangeExit; t += iterationSize)
                        {
                            Vector3d pos            = patch.SpaceOrbit.getRelativePositionAtUT(t);
                            double   groundAltitude = GetGroundAltitude(body, CalculateRotatedPosition(body, pos.SwapYZ(), t))
                                                      + body.Radius;
                            if (pos.magnitude < groundAltitude)
                            {
                                t           -= iterationSize;
                                groundImpact = true;
                                break;
                            }
                        }

                        if (groundImpact)
                        {
                            patch.EndTime           = t;
                            patch.RawImpactPosition = patch.SpaceOrbit.getRelativePositionAtUT(t).SwapYZ();
                            patch.ImpactPosition    = CalculateRotatedPosition(body, patch.RawImpactPosition.Value, t);
                            patch.ImpactVelocity    = patch.SpaceOrbit.getOrbitalVelocityAtUT(t).SwapYZ();
                            patchesBackBuffer_.Add(patch);
                            AddPatch_outState = null;
                        }
                        else
                        {
                            // no impact, just add the space orbit
                            patchesBackBuffer_.Add(patch);
                            if (nextPatch != null)
                            {
                                AddPatch_outState = new VesselState
                                {
                                    Position      = patch.SpaceOrbit.getRelativePositionAtUT(patch.EndTime).SwapYZ(),
                                    Velocity      = patch.SpaceOrbit.getOrbitalVelocityAtUT(patch.EndTime).SwapYZ(),
                                    ReferenceBody = nextPatch.referenceBody,
                                    Time          = patch.EndTime,
                                    StockPatch    = nextPatch
                                };
                            }
                            else
                            {
                                AddPatch_outState = null;
                            }
                        }
                    }
                }
                else
                {
                    if (patch.StartingState.ReferenceBody != AttachedVessel.mainBody)
                    {
                        // currently, we can't handle predictions for another body, so we stop
                        AddPatch_outState = null;
                        yield break;
                    }

                    // simulate atmospheric flight (drag and lift), until impact or atmosphere exit
                    // (typically for an aerobraking maneuver) assuming a constant angle of attack
                    patch.IsAtmospheric            = true;
                    patch.StartingState.StockPatch = null;

                    // lower dt would be more accurate, but a trade-off has to be found between performances and accuracy
                    double dt = Settings.IntegrationStepSize;

                    // some shallow entries can result in very long flight. For performances reasons,
                    // we limit the prediction duration
                    int maxIterations = (int)(60.0 * 60.0 / dt);

                    int chunkSize = 128;

                    // time between two consecutive stored positions (more intermediate positions are computed for better accuracy),
                    // also used for ground collision checks
                    double trajectoryInterval = 10.0;

                    List <Point[]> buffer = new List <Point[]>
                    {
                        new Point[chunkSize]
                    };
                    int nextPosIdx = 0;

                    SimulationState state;
                    state.position = patch.SpaceOrbit.getRelativePositionAtUT(entryTime).SwapYZ();
                    state.velocity = patch.SpaceOrbit.getOrbitalVelocityAtUT(entryTime).SwapYZ();

                    // Initialize a patch with zero acceleration
                    Vector3d currentAccel = new Vector3d(0.0, 0.0, 0.0);


                    double   currentTime               = entryTime;
                    double   lastPositionStoredUT      = 0;
                    Vector3d lastPositionStored        = new Vector3d();
                    bool     hitGround                 = false;
                    int      iteration                 = 0;
                    int      incrementIterations       = 0;
                    int      minIterationsPerIncrement = maxIterations / Settings.MaxFramesPerPatch;

                    #region Acceleration Functor

                    // function that calculates the acceleration under current parameters
                    Vector3d AccelerationFunc(Vector3d position, Vector3d velocity)
                    {
                        Profiler.Start("accelerationFunc inside");

                        // gravity acceleration
                        double   R_      = position.magnitude;
                        Vector3d accel_g = position * (-body.gravParameter / (R_ * R_ * R_));

                        // aero force
                        Vector3d vel_air = velocity - body.getRFrmVel(body.position + position);

                        double aoa = DescentProfile.GetAngleOfAttack(body, position, vel_air) ?? 0d;

                        Profiler.Start("GetForces");
                        Vector3d force_aero = aerodynamicModel_.GetForces(body, position, vel_air, aoa);

                        Profiler.Stop("GetForces");

                        Vector3d accel = accel_g + force_aero / aerodynamicModel_.Mass;

                        accel += API.HandleAccel(AttachedVessel, body, position, velocity, aoa);

                        Profiler.Stop("accelerationFunc inside");
                        return(accel);
                    }

                    #endregion


                    #region Integration Loop

                    while (true)
                    {
                        ++iteration;
                        ++incrementIterations;

                        if (incrementIterations > minIterationsPerIncrement && Util.ElapsedMilliseconds(increment_time) > MAX_INCREMENT_TIME)
                        {
                            yield return(false);

                            incrementIterations = 0;
                        }


                        double R               = state.position.magnitude;
                        double altitude        = R - body.Radius;
                        double atmosphereCoeff = altitude / maxAtmosphereAltitude;
                        if (hitGround ||
                            atmosphereCoeff <= 0.0 || atmosphereCoeff >= 1.0 ||
                            iteration == maxIterations || currentTime > patch.EndTime)
                        {
                            //Util.PostSingleScreenMessage("atmo force", "Atmospheric accumulated force: " + accumulatedForces.ToString("0.00"));

                            if (hitGround || atmosphereCoeff <= 0.0)
                            {
                                patch.RawImpactPosition = state.position;
                                patch.ImpactPosition    = CalculateRotatedPosition(body, patch.RawImpactPosition.Value, currentTime);
                                patch.ImpactVelocity    = state.velocity;
                            }

                            patch.EndTime = Math.Min(currentTime, patch.EndTime);

                            int totalCount = (buffer.Count - 1) * chunkSize + nextPosIdx;
                            patch.AtmosphericTrajectory = new Point[totalCount];
                            int outIdx = 0;
                            foreach (Point[] chunk in buffer)
                            {
                                foreach (Point p in chunk)
                                {
                                    if (outIdx == totalCount)
                                    {
                                        break;
                                    }
                                    patch.AtmosphericTrajectory[outIdx++] = p;
                                }
                            }

                            if (iteration == maxIterations)
                            {
                                ScreenMessages.PostScreenMessage("WARNING: trajectory prediction stopped, too many iterations");
                                patchesBackBuffer_.Add(patch);
                                AddPatch_outState = null;
                                yield break;
                            }

                            if (atmosphereCoeff <= 0.0 || hitGround)
                            {
                                patchesBackBuffer_.Add(patch);
                                AddPatch_outState = null;
                                yield break;
                            }

                            patchesBackBuffer_.Add(patch);
                            AddPatch_outState = new VesselState
                            {
                                Position      = state.position,
                                Velocity      = state.velocity,
                                ReferenceBody = body,
                                Time          = patch.EndTime
                            };
                            yield break;
                        }

                        Vector3d        lastAccel = currentAccel;
                        SimulationState lastState = state;

                        Profiler.Start("IntegrationStep");

                        // Verlet integration (more precise than using the velocity)
                        // state = VerletStep(state, accelerationFunc, dt);
                        state = RK4Step(state, AccelerationFunc, dt, out currentAccel);

                        currentTime += dt;

                        // KSP presumably uses Euler integration for position updates. Since RK4 is actually more precise than that,
                        // we try to reintroduce an approximation of the error.

                        // The local truncation error for euler integration is:
                        // LTE = 1/2 * h^2 * y''(t)
                        // https://en.wikipedia.org/wiki/Euler_method#Local_truncation_error
                        //
                        // For us,
                        // h is the time step of the outer simulation (KSP), which is the physics time step
                        // y''(t) is the difference of the velocity/acceleration divided by the physics time step
                        state.position += 0.5 * TimeWarp.fixedDeltaTime * currentAccel * dt;
                        state.velocity += 0.5 * TimeWarp.fixedDeltaTime * (currentAccel - lastAccel);

                        Profiler.Stop("IntegrationStep");

                        // calculate gravity and aerodynamic force
                        Vector3d gravityAccel     = lastState.position * (-body.gravParameter / (R * R * R));
                        Vector3d aerodynamicForce = (currentAccel - gravityAccel) / aerodynamicModel_.Mass;

                        // acceleration in the vessel reference frame is acceleration - gravityAccel
                        maxAccelBackBuffer_ = Math.Max(
                            (float)(aerodynamicForce.magnitude / aerodynamicModel_.Mass),
                            maxAccelBackBuffer_);

                        #region Impact Calculation

                        Profiler.Start("AddPatch#impact");

                        double interval = altitude < 10000.0 ? trajectoryInterval * 0.1 : trajectoryInterval;
                        if (currentTime >= lastPositionStoredUT + interval)
                        {
                            double groundAltitude = GetGroundAltitude(body, CalculateRotatedPosition(body, state.position, currentTime));
                            if (lastPositionStoredUT > 0)
                            {
                                // check terrain collision, to detect impact on mountains etc.
                                Vector3 rayOrigin         = lastPositionStored;
                                Vector3 rayEnd            = state.position;
                                double  absGroundAltitude = groundAltitude + body.Radius;
                                if (absGroundAltitude > rayEnd.magnitude)
                                {
                                    hitGround = true;
                                    float coeff = Math.Max(0.01f, (float)((absGroundAltitude - rayOrigin.magnitude)
                                                                          / (rayEnd.magnitude - rayOrigin.magnitude)));
                                    state.position = rayEnd * coeff + rayOrigin * (1.0f - coeff);
                                    currentTime    = currentTime * coeff + lastPositionStoredUT * (1.0f - coeff);
                                }
                            }

                            lastPositionStoredUT = currentTime;
                            if (nextPosIdx == chunkSize)
                            {
                                buffer.Add(new Point[chunkSize]);
                                nextPosIdx = 0;
                            }

                            Vector3d nextPos = state.position;
                            if (Settings.BodyFixedMode)
                            {
                                nextPos = CalculateRotatedPosition(body, nextPos, currentTime);
                            }

                            buffer.Last()[nextPosIdx].aerodynamicForce = aerodynamicForce;
                            buffer.Last()[nextPosIdx].orbitalVelocity  = state.velocity;
                            buffer.Last()[nextPosIdx].groundAltitude   = (float)groundAltitude;
                            buffer.Last()[nextPosIdx].time             = currentTime;
                            buffer.Last()[nextPosIdx++].pos            = nextPos;
                            lastPositionStored = state.position;
                        }

                        Profiler.Stop("AddPatch#impact");

                        #endregion
                    }

                    #endregion
                }
            }
            else
            {
                // no atmospheric entry, just add the space orbit
                patchesBackBuffer_.Add(patch);
                if (nextPatch != null)
                {
                    AddPatch_outState = new VesselState
                    {
                        Position      = patch.SpaceOrbit.getRelativePositionAtUT(patch.EndTime).SwapYZ(),
                        Velocity      = patch.SpaceOrbit.getOrbitalVelocityAtUT(patch.EndTime).SwapYZ(),
                        ReferenceBody = nextPatch.referenceBody,
                        Time          = patch.EndTime,
                        StockPatch    = nextPatch
                    };
                }
                else
                {
                    AddPatch_outState = null;
                }
            }
        }
Example #4
0
        /// <summary>
        /// Compute the aerodynamic forces that would be applied to the vessel if it was in the specified situation (air velocity, altitude and angle of attack).
        /// </summary>
        /// <returns>The computed aerodynamic forces in world space</returns>
        public Vector3d ComputeForces(double altitude, Vector3d airVelocity, Vector3d vup, double angleOfAttack)
        {
            Profiler.Start("ComputeForces");
            if (!Trajectories.IsVesselAttached || !Trajectories.AttachedVessel.mainBody.atmosphere || altitude >= body_.atmosphereDepth)
            {
                return(Vector3d.zero);
            }

            Transform vesselTransform = Trajectories.AttachedVessel.ReferenceTransform;

            if (vesselTransform == null)
            {
                return(Vector3d.zero);
            }

            // this is weird, but the vessel orientation does not match the reference transform (up is forward), this code fixes it but I don't know if it'll work in all cases
            Vector3d vesselBackward = -vesselTransform.up.normalized;
            Vector3d vesselForward  = -vesselBackward;
            Vector3d vesselUp       = -vesselTransform.forward.normalized;
            Vector3d vesselRight    = Vector3d.Cross(vesselUp, vesselBackward).normalized;

            Vector3d airVelocityForFixedAoA = (vesselForward * Math.Cos(-angleOfAttack) + vesselUp * Math.Sin(-angleOfAttack)) * airVelocity.magnitude;

            Vector3d totalForce = ComputeForces_Model(airVelocityForFixedAoA, altitude);

            if (double.IsNaN(totalForce.x) || double.IsNaN(totalForce.y) || double.IsNaN(totalForce.z))
            {
                Util.LogWarning("{0} totalForce is NaN (altitude={1}, airVelocity={2}, angleOfAttack={3}", AerodynamicModelName, altitude, airVelocity.magnitude, angleOfAttack);
                return(Vector3d.zero); // Don't send NaN into the simulation as it would cause bad things (infinite loops, crash, etc.). I think this case only happens at the atmosphere edge, so the total force should be 0 anyway.
            }

            // convert the force computed by the model (depends on the current vessel orientation, which is irrelevant for the prediction) to the predicted vessel orientation (which depends on the predicted velocity)
            Vector3d localForce = new Vector3d(Vector3d.Dot(vesselRight, totalForce), Vector3d.Dot(vesselUp, totalForce), Vector3d.Dot(vesselBackward, totalForce));

            //if (Double.IsNaN(localForce.x) || Double.IsNaN(localForce.y) || Double.IsNaN(localForce.z))
            //    throw new Exception("localForce is NAN");

            Vector3d velForward  = airVelocity.normalized;
            Vector3d velBackward = -velForward;
            Vector3d velRight    = Vector3d.Cross(vup, velBackward);

            if (velRight.sqrMagnitude < 0.001)
            {
                velRight = Vector3d.Cross(vesselUp, velBackward);
                if (velRight.sqrMagnitude < 0.001)
                {
                    velRight = Vector3d.Cross(vesselBackward, velBackward).normalized;
                }
                else
                {
                    velRight = velRight.normalized;
                }
            }
            else
            {
                velRight = velRight.normalized;
            }
            Vector3d velUp = Vector3d.Cross(velBackward, velRight).normalized;

            Vector3d predictedVesselForward  = velForward * Math.Cos(angleOfAttack) + velUp * Math.Sin(angleOfAttack);
            Vector3d predictedVesselBackward = -predictedVesselForward;
            Vector3d predictedVesselRight    = velRight;
            Vector3d predictedVesselUp       = Vector3d.Cross(predictedVesselBackward, predictedVesselRight).normalized;

            Vector3d res = predictedVesselRight * localForce.x + predictedVesselUp * localForce.y + predictedVesselBackward * localForce.z;

            if (double.IsNaN(res.x) || double.IsNaN(res.y) || double.IsNaN(res.z))
            {
                Util.LogWarning("{0} res is NaN (altitude={1}, airVelocity={2}, angleOfAttack={3}", AerodynamicModelName, altitude, airVelocity.magnitude, angleOfAttack);
                return(new Vector3d(0, 0, 0)); // Don't send NaN into the simulation as it would cause bad things (infinite loops, crash, etc.). I think this case only happens at the atmosphere edge, so the total force should be 0 anyway.
            }


            Profiler.Stop("ComputeForces");
            return(res);
        }
Example #5
0
        //*******************************************************
        public static Vector3d SimAeroForce(Vector3d v_wrld_vel, double altitude, double latitude = 0.0)
        {
            Profiler.Start("SimAeroForce");

            CelestialBody body     = Trajectories.AttachedVessel.mainBody;
            double        pressure = body.GetPressure(altitude);
            // Lift and drag for force accumulation.
            Vector3d total_lift = Vector3d.zero;
            Vector3d total_drag = Vector3d.zero;

            // dynamic pressure for standard drag equation
            double rho          = GetDensity(altitude, body);
            double dyn_pressure = 0.0005 * rho * v_wrld_vel.sqrMagnitude;

            if (rho <= 0)
            {
                return(Vector3.zero);
            }

            double soundSpeed = body.GetSpeedOfSound(pressure, rho);
            double mach       = v_wrld_vel.magnitude / soundSpeed;

            if (mach > 25.0)
            {
                mach = 25.0;
            }

            // Loop through all parts, accumulating drag and lift.
            for (int i = 0; i < Trajectories.AttachedVessel.Parts.Count; ++i)
            {
                // need checks on shielded components
                Part p = Trajectories.AttachedVessel.Parts[i];
                #if DEBUG
                TrajectoriesDebug partDebug = VesselAerodynamicModel.DebugParts ? p.FindModuleImplementing <TrajectoriesDebug>() : null;
                if (partDebug != null)
                {
                    partDebug.Drag = 0;
                    partDebug.Lift = 0;
                }
                #endif

                if (p.ShieldedFromAirstream || p.Rigidbody == null)
                {
                    continue;
                }

                // Get Drag
                Vector3d sim_dragVectorDir      = v_wrld_vel.normalized;
                Vector3d sim_dragVectorDirLocal = -(p.transform.InverseTransformDirection(sim_dragVectorDir));

                Vector3d liftForce = Vector3d.zero;
                Vector3d dragForce;


                Profiler.Start("SimAeroForce#drag");
                switch (p.dragModel)
                {
                case Part.DragModel.DEFAULT:
                case Part.DragModel.CUBE:
                    DragCubeList cubes = p.DragCubes;

                    DragCubeList.CubeData p_drag_data = new DragCubeList.CubeData();

                    double drag;
                    if (cubes.None)     // since 1.0.5, some parts don't have drag cubes (for example fuel lines and struts)
                    {
                        drag = p.maximum_drag;
                    }
                    else
                    {
                        try
                        {
                            cubes.AddSurfaceDragDirection(-sim_dragVectorDirLocal, (float)mach, ref p_drag_data);
                        }
                        catch (Exception e)
                        {
                            cubes.SetDrag(sim_dragVectorDirLocal, (float)mach);
                            cubes.ForceUpdate(true, true);
                            cubes.AddSurfaceDragDirection(-sim_dragVectorDirLocal, (float)mach, ref p_drag_data);
                            Util.DebugLogError("Exception {0} on drag initialization", e);
                        }

                        double pseudoreynolds   = rho * Math.Abs(v_wrld_vel.magnitude);
                        double pseudoredragmult = PhysicsGlobals.DragCurvePseudoReynolds.Evaluate((float)pseudoreynolds);
                        drag = p_drag_data.areaDrag * PhysicsGlobals.DragCubeMultiplier * pseudoredragmult;

                        liftForce = p_drag_data.liftForce;
                    }

                    double sim_dragScalar = dyn_pressure * drag * PhysicsGlobals.DragMultiplier;
                    dragForce = -sim_dragVectorDir * sim_dragScalar;

                    break;

                case Part.DragModel.SPHERICAL:
                    dragForce = -sim_dragVectorDir * p.maximum_drag;
                    break;

                case Part.DragModel.CYLINDRICAL:
                    dragForce = -sim_dragVectorDir *Mathf.Lerp(p.minimum_drag, p.maximum_drag, Mathf.Abs(Vector3.Dot(p.partTransform.TransformDirection(p.dragReferenceVector), sim_dragVectorDir)));

                    break;

                case Part.DragModel.CONIC:
                    dragForce = -sim_dragVectorDir *Mathf.Lerp(p.minimum_drag, p.maximum_drag, Vector3.Angle(p.partTransform.TransformDirection(p.dragReferenceVector), sim_dragVectorDir) / 180f);

                    break;

                default:
                    // no drag to apply
                    dragForce = Vector3d.zero;
                    break;
                }

                Profiler.Stop("SimAeroForce#drag");

#if DEBUG
                if (partDebug != null)
                {
                    partDebug.Drag += (float)dragForce.magnitude;
                }
                #endif
                total_drag += dragForce;

                // If it isn't a wing or lifter, get body lift.
                if (!p.hasLiftModule)
                {
                    Profiler.Start("SimAeroForce#BodyLift");

                    float simbodyLiftScalar = p.bodyLiftMultiplier * PhysicsGlobals.BodyLiftMultiplier * (float)dyn_pressure;
                    simbodyLiftScalar *= PhysicsGlobals.GetLiftingSurfaceCurve("BodyLift").liftMachCurve.Evaluate((float)mach);
                    Vector3 bodyLift = p.transform.rotation * (simbodyLiftScalar * liftForce);
                    bodyLift = Vector3.ProjectOnPlane(bodyLift, sim_dragVectorDir);
                    // Only accumulate forces for non-LiftModules
                    total_lift += bodyLift;


                    Profiler.Stop("SimAeroForce#BodyLift");
                }


                Profiler.Start("SimAeroForce#LiftingSurface");

                // Find ModuleLifingSurface for wings and liftforce.
                // Should catch control surface as it is a subclass
                for (int j = 0; j < p.Modules.Count; ++j)
                {
                    var   m = p.Modules[j];
                    float mcs_mod;
                    if (m is ModuleLiftingSurface)
                    {
                        mcs_mod = 1.0f;
                        double liftQ = dyn_pressure * 1000;
                        ModuleLiftingSurface wing = (ModuleLiftingSurface)m;
                        Vector3 nVel       = Vector3.zero;
                        Vector3 liftVector = Vector3.zero;
                        float   liftdot;
                        float   absdot;
                        wing.SetupCoefficients(v_wrld_vel, out nVel, out liftVector, out liftdot, out absdot);

                        double prevMach = p.machNumber;
                        p.machNumber = mach;
                        Vector3 local_lift = mcs_mod * wing.GetLiftVector(liftVector, liftdot, absdot, liftQ, (float)mach);
                        Vector3 local_drag = mcs_mod * wing.GetDragVector(nVel, absdot, liftQ);
                        p.machNumber = prevMach;

                        total_lift += local_lift;
                        total_drag += local_drag;

                        #if DEBUG
                        if (partDebug != null)
                        {
                            partDebug.Lift += (float)local_lift.magnitude;
                            partDebug.Drag += (float)local_drag.magnitude;
                        }
                        #endif
                    }
                }

                Profiler.Stop("SimAeroForce#LiftingSurface");
            }
            // RETURN STUFF
            Vector3 force = total_lift + total_drag;

            Profiler.Stop("SimAeroForce");
            return(force);
        }
Example #6
0
 public ProfileScope(string name)
 {
     this.name = name;
     Profiler.Start(name);
 }