/*
 * Copyright (c) Contributors, http://opensimulator.org/
 * See CONTRIBUTORS.TXT for a full list of copyright holders.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyrightD
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the OpenSimulator Project nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
using System;
using System.Collections.Generic;
using System.Reflection;
using System.Text;

using OpenSim.Region.PhysicsModules.SharedBase;

using OpenMetaverse;
using Nini.Config;

namespace OpenSim.Region.PhysicsModule.BulletS
{
    public static class BSParam
    {
        private static string LogHeader = "[BULLETSIM PARAMETERS]";

        // Tuning notes:
        // From: http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?t=6575
        //    Contact points can be added even if the distance is positive. The constraint solver can deal with
        //    contacts with positive distances as well as negative (penetration). Contact points are discarded
        //    if the distance exceeds a certain threshold.
        //    Bullet has a contact processing threshold and a contact breaking threshold.
        //    If the distance is larger than the contact breaking threshold, it will be removed after one frame.
        //    If the distance is larger than the contact processing threshold, the constraint solver will ignore it.

        //    This is separate/independent from the collision margin. The collision margin increases the object a bit
        //    to improve collision detection performance and accuracy.
        // ===================
        // From:

        /// <summary>
        /// Set whether physics is active or not.
        /// </summary>
        /// <remarks>
        /// Can be enabled and disabled to start and stop physics.
        /// </remarks>
        public static bool Active { get; private set; }

        public static bool UseSeparatePhysicsThread { get; private set; }
        public static float PhysicsTimeStep { get; private set; }

        // Level of Detail values kept as float because that's what the Meshmerizer wants
        public static float MeshLOD { get; private set; }
        public static float MeshCircularLOD { get; private set; }
        public static float MeshMegaPrimLOD { get; private set; }
        public static float MeshMegaPrimThreshold { get; private set; }
        public static float SculptLOD { get; private set; }

        public static int CrossingFailuresBeforeOutOfBounds { get; private set; }
        public static float UpdateVelocityChangeThreshold { get; private set; }

        public static float MinimumObjectMass { get; private set; }
        public static float MaximumObjectMass { get; private set; }
        public static float MaxLinearVelocity { get; private set; }
        public static float MaxLinearVelocitySquared { get; private set; }
        public static float MaxAngularVelocity { get; private set; }
        public static float MaxAngularVelocitySquared { get; private set; }
        public static float MaxAddForceMagnitude { get; private set; }
        public static float MaxAddForceMagnitudeSquared { get; private set; }
        public static float DensityScaleFactor { get; private set; }

        public static float LinearDamping { get; private set; }
        public static float AngularDamping { get; private set; }
        public static float DeactivationTime { get; private set; }
        public static float LinearSleepingThreshold { get; private set; }
        public static float AngularSleepingThreshold { get; private set; }
        public static float CcdMotionThreshold { get; private set; }
        public static float CcdSweptSphereRadius { get; private set; }
        public static float ContactProcessingThreshold { get; private set; }

        public static bool ShouldMeshSculptedPrim { get; private set; }   // cause scuplted prims to get meshed
        public static bool ShouldForceSimplePrimMeshing { get; private set; }   // if a cube or sphere, let Bullet do internal shapes
        public static bool ShouldUseHullsForPhysicalObjects { get; private set; }   // 'true' if should create hulls for physical objects
        public static bool ShouldRemoveZeroWidthTriangles { get; private set; }
        public static bool ShouldUseBulletHACD { get; set; }
        public static bool ShouldUseSingleConvexHullForPrims { get; set; }
        public static bool ShouldUseGImpactShapeForPrims { get; set; }
        public static bool ShouldUseAssetHulls { get; set; }

        public static float TerrainImplementation { get; set; }
        public static int TerrainMeshMagnification { get; private set; }
        public static float TerrainGroundPlane { get; private set; }
        public static float TerrainFriction { get; private set; }
        public static float TerrainHitFraction { get; private set; }
        public static float TerrainRestitution { get; private set; }
        public static float TerrainContactProcessingThreshold { get; private set; }
        public static float TerrainCollisionMargin { get; private set; }

        public static float DefaultFriction { get; private set; }
        public static float DefaultDensity { get; private set; }
        public static float DefaultRestitution { get; private set; }
        public static float CollisionMargin { get; private set; }
        public static float Gravity { get; private set; }

        // Physics Engine operation
        public static float MaxPersistantManifoldPoolSize { get; private set; }
        public static float MaxCollisionAlgorithmPoolSize { get; private set; }
        public static bool ShouldDisableContactPoolDynamicAllocation { get; private set; }
        public static bool ShouldForceUpdateAllAabbs { get; private set; }
        public static bool ShouldRandomizeSolverOrder { get; private set; }
        public static bool ShouldSplitSimulationIslands { get; private set; }
        public static bool ShouldEnableFrictionCaching { get; private set; }
        public static float NumberOfSolverIterations { get; private set; }
        public static bool UseSingleSidedMeshes { get; private set; }
        public static float GlobalContactBreakingThreshold { get; private set; }
        public static float PhysicsUnmanLoggingFrames { get; private set; }

        // Avatar parameters
        public static bool AvatarToAvatarCollisionsByDefault { get; private set; }
        public static float AvatarFriction { get; private set; }
        public static float AvatarStandingFriction { get; private set; }
        public static float AvatarWalkVelocityFactor { get; private set; }
        public static float AvatarAlwaysRunFactor { get; private set; }
        public static float AvatarDensity { get; private set; }
        public static float AvatarRestitution { get; private set; }
        public static int AvatarShape { get; private set; }
        public static float AvatarCapsuleWidth { get; private set; }
        public static float AvatarCapsuleDepth { get; private set; }
        public static float AvatarCapsuleHeight { get; private set; }
        public static bool AvatarUseBefore09SizeComputation { get; private set; }
        public static float AvatarHeightLowFudge { get; private set; }
        public static float AvatarHeightMidFudge { get; private set; }
        public static float AvatarHeightHighFudge { get; private set; }
        public static float AvatarFlyingGroundMargin { get; private set; }
        public static float AvatarFlyingGroundUpForce { get; private set; }
        public static int AvatarAddForceFrames { get; private set; }
        public static float AvatarTerminalVelocity { get; private set; }
        public static float AvatarContactProcessingThreshold { get; private set; }
        public static float AvatarAddForcePushFactor { get; private set; }
        public static float AvatarStopZeroThreshold { get; private set; }
        public static float AvatarStopZeroThresholdSquared { get; private set; }
        public static int AvatarJumpFrames { get; private set; }
        public static float AvatarBelowGroundUpCorrectionMeters { get; private set; }
        public static float AvatarStepHeight { get; private set; }
        public static float AvatarStepAngle { get; private set; }
        public static float AvatarStepGroundFudge { get; private set; }
        public static float AvatarStepApproachFactor { get; private set; }
        public static float AvatarStepForceFactor { get; private set; }
        public static float AvatarStepUpCorrectionFactor { get; private set; }
        public static int AvatarStepSmoothingSteps { get; private set; }

        // Vehicle parameters
        public static float VehicleMaxLinearVelocity { get; private set; }
        public static float VehicleMaxLinearVelocitySquared { get; private set; }
        public static float VehicleMinLinearVelocity { get; private set; }
        public static float VehicleMinLinearVelocitySquared { get; private set; }
        public static float VehicleMaxAngularVelocity { get; private set; }
        public static float VehicleMaxAngularVelocitySq { get; private set; }
        public static float VehicleAngularDamping { get; private set; }
        public static float VehicleFriction { get; private set; }
        public static float VehicleRestitution { get; private set; }
        public static Vector3 VehicleLinearFactor { get; private set; }
        public static Vector3 VehicleAngularFactor { get; private set; }
        public static Vector3 VehicleInertiaFactor { get; private set; }
        public static float VehicleGroundGravityFudge { get; private set; }
        public static float VehicleAngularBankingTimescaleFudge { get; private set; }
        public static bool VehicleEnableLinearDeflection { get; private set; }
        public static bool VehicleLinearDeflectionNotCollidingNoZ { get; private set; }
        public static bool VehicleEnableAngularVerticalAttraction { get; private set; }
        public static int VehicleAngularVerticalAttractionAlgorithm { get; private set; }
        public static bool VehicleEnableAngularDeflection { get; private set; }
        public static bool VehicleEnableAngularBanking { get; private set; }

        // Convex Hulls
        // Parameters for convex hull routine that ships with Bullet
        public static int CSHullMaxDepthSplit { get; private set; }
        public static int CSHullMaxDepthSplitForSimpleShapes { get; private set; }
        public static float CSHullConcavityThresholdPercent { get; private set; }
        public static float CSHullVolumeConservationThresholdPercent { get; private set; }
        public static int CSHullMaxVertices { get; private set; }
        public static float CSHullMaxSkinWidth { get; private set; }
        public static float BHullMaxVerticesPerHull { get; private set; }       // 100
        public static float BHullMinClusters { get; private set; }              // 2
        public static float BHullCompacityWeight { get; private set; }          // 0.1
        public static float BHullVolumeWeight { get; private set; }             // 0.0
        public static float BHullConcavity { get; private set; }                // 100
        public static bool BHullAddExtraDistPoints { get; private set; }        // false
        public static bool BHullAddNeighboursDistPoints { get; private set; }   // false
        public static bool BHullAddFacesPoints { get; private set; }            // false
        public static bool BHullShouldAdjustCollisionMargin { get; private set; }   // false
        public static float WhichHACD { get; private set; }                // zero if Bullet HACD, non-zero says VHACD
        // Parameters for VHACD 2.0: http://code.google.com/p/v-hacd
        // To enable, set both ShouldUseBulletHACD=true and WhichHACD=1
        // http://kmamou.blogspot.ca/2014/12/v-hacd-20-parameters-description.html
        public static float VHACDresolution { get; private set; }           // 100,000 max number of voxels generated during voxelization stage
        public static float VHACDdepth { get; private set; }                // 20 max number of clipping stages
        public static float VHACDconcavity { get; private set; }            // 0.0025 maximum concavity
        public static float VHACDplaneDownsampling { get; private set; }    // 4 granularity of search for best clipping plane
        public static float VHACDconvexHullDownsampling { get; private set; }    // 4 precision of hull gen process
        public static float VHACDalpha { get; private set; }                // 0.05 bias toward clipping along symmetry planes
        public static float VHACDbeta { get; private set; }                 // 0.05 bias toward clipping along revolution axis
        public static float VHACDgamma { get; private set; }                // 0.00125 max concavity when merging
        public static float VHACDpca { get; private set; }                  // 0 on/off normalizing mesh before decomp
        public static float VHACDmode { get; private set; }                 // 0 0:voxel based, 1: tetrahedron based
        public static float VHACDmaxNumVerticesPerCH { get; private set; }  // 64 max triangles per convex hull
        public static float VHACDminVolumePerCH { get; private set; }       // 0.0001 sampling of generated convex hulls

        // Linkset implementation parameters
        public static float LinksetImplementation { get; private set; }
        public static bool LinksetOffsetCenterOfMass { get; private set; }
        public static bool LinkConstraintUseFrameOffset { get; private set; }
        public static bool LinkConstraintEnableTransMotor { get; private set; }
        public static float LinkConstraintTransMotorMaxVel { get; private set; }
        public static float LinkConstraintTransMotorMaxForce { get; private set; }
        public static float LinkConstraintERP { get; private set; }
        public static float LinkConstraintCFM { get; private set; }
        public static float LinkConstraintSolverIterations { get; private set; }

        public static bool UseBulletRaycast { get; private set; }

        public static float PID_D { get; private set; }    // derivative
        public static float PID_P { get; private set; }    // proportional

        // The reported version from the underylying DLL/SO could be the legacy value
        // If the legacy value, this other value is returned
        public static string VersionLegacyValue { get; private set; }
        public static string VersionLegacyReplacement { get; private set; }

        public static float DebugNumber { get; private set; }   // A console setable number used for debugging

        // Various constants that come from that other virtual world that shall not be named.
        public const float MinGravityZ = -1f;
        public const float MaxGravityZ = 28f;
        public const float MinFriction = 0f;
        public const float MaxFriction = 255f;
        public const float MinDensity = 0.01f;
        public const float MaxDensity = 22587f;
        public const float MinRestitution = 0f;
        public const float MaxRestitution = 1f;

        // =====================================================================================
        // =====================================================================================

        // Base parameter definition that gets and sets parameter values via a string
        public abstract class ParameterDefnBase
        {
            public string name;         // string name of the parameter
            public string desc;         // a short description of what the parameter means
            public ParameterDefnBase(string pName, string pDesc)
            {
                name = pName;
                desc = pDesc;
            }
            // Set the parameter value to the default
            public abstract void AssignDefault(BSScene s);
            // Get the value as a string
            public abstract string GetValue(BSScene s);
            // Set the value to this string value
            public abstract void SetValue(BSScene s, string valAsString);
            // set the value on a particular object (usually sets in physics engine)
            public abstract void SetOnObject(BSScene s, BSPhysObject obj);
            public abstract bool HasSetOnObject { get; }
        }

        // Specific parameter definition for a parameter of a specific type.
        public delegate T PGetValue<T>(BSScene s);
        public delegate void PSetValue<T>(BSScene s, T val);
        public delegate void PSetOnObject<T>(BSScene scene, BSPhysObject obj);
        public sealed class ParameterDefn<T> : ParameterDefnBase
        {
            private T defaultValue;
            private PSetValue<T> setter;
            private PGetValue<T> getter;
            private PSetOnObject<T> objectSet;
            public ParameterDefn(string pName, string pDesc, T pDefault, PGetValue<T> pGetter, PSetValue<T> pSetter)
                : base(pName, pDesc)
            {
                defaultValue = pDefault;
                setter = pSetter;
                getter = pGetter;
                objectSet = null;
            }
            public ParameterDefn(string pName, string pDesc, T pDefault, PGetValue<T> pGetter, PSetValue<T> pSetter, PSetOnObject<T> pObjSetter)
                : base(pName, pDesc)
            {
                defaultValue = pDefault;
                setter = pSetter;
                getter = pGetter;
                objectSet = pObjSetter;
            }
            // Simple parameter variable where property name is the same as the INI file name
            //     and the value is only a simple get and set.
            public ParameterDefn(string pName, string pDesc, T pDefault)
                : base(pName, pDesc)
            {
                defaultValue = pDefault;
                setter = (s, v) => { SetValueByName(s, name, v); };
                getter = (s) => { return GetValueByName(s, name); };
                objectSet = null;
            }
            // Use reflection to find the property named 'pName' in BSParam and assign 'val' to same.
            private void SetValueByName(BSScene s, string pName, T val)
            {
                PropertyInfo prop = typeof(BSParam).GetProperty(pName, BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy);
                if (prop == null)
                {
                    // This should only be output when someone adds a new INI parameter and misspells the name.
                    s.Logger.ErrorFormat("{0} SetValueByName: did not find '{1}'. Verify specified property name is the same as the given INI parameters name.", LogHeader, pName);
                }
                else
                {
                    prop.SetValue(null, val, null);
                }
            }
            // Use reflection to find the property named 'pName' in BSParam and return the value in same.
            private T GetValueByName(BSScene s, string pName)
            {
                PropertyInfo prop = typeof(BSParam).GetProperty(pName, BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy);
                if (prop == null)
                {
                    // This should only be output when someone adds a new INI parameter and misspells the name.
                    s.Logger.ErrorFormat("{0} GetValueByName: did not find '{1}'. Verify specified property name is the same as the given INI parameter name.", LogHeader, pName);
                }
                return (T)prop.GetValue(null, null);
            }
            public override void AssignDefault(BSScene s)
            {
                setter(s, defaultValue);
            }
            public override string GetValue(BSScene s)
            {
                return getter(s).ToString();
            }
            public override void SetValue(BSScene s, string valAsString)
            {
                // Get the generic type of the setter
                Type genericType = setter.GetType().GetGenericArguments()[0];
                if (genericType == typeof(string))
                {
                    try
                    {
                        setter(s, defaultValue);
                    }
                    catch
                    {
                        s.Logger.Error($"{LogHeader} Failed setting string parameter value '{valAsString}'");
                    }
                    return;
                }

                // Find the 'Parse' method on that type
                System.Reflection.MethodInfo parser = null;
                try
                {
                    parser = genericType.GetMethod("Parse", new Type[] { typeof(String) } );
                }
                catch (Exception e)
                {
                    s.Logger.Error($"{LogHeader} Exception getting parser for type '{genericType}': {e.Message}");
                    return;
                }
                if (parser != null)
                {
                    // Parse the input string
                    try
                    {
                        T setValue = (T)parser.Invoke(genericType, new Object[] { valAsString });
                        // Store the parsed value
                        setter(s, setValue);
                        // s.Logger.DebugFormat("{0} Parameter {1} = {2}", LogHeader, name, setValue);
                    }
                    catch
                    {
                        s.Logger.Error($"{LogHeader} Failed parsing parameter value '{valAsString}' as type '{genericType}'");
                    }
                }
                else
                    s.Logger.Error($"{LogHeader} Could not find parameter parser for type '{genericType}'");
            }
            public override bool HasSetOnObject
            {
                get { return objectSet != null; }
            }
            public override void SetOnObject(BSScene s, BSPhysObject obj)
            {
                if (objectSet != null)
                    objectSet(s, obj);
            }
        }

        // List of all of the externally visible parameters.
        // For each parameter, this table maps a text name to getter and setters.
        // To add a new externally referencable/settable parameter, add the paramter storage
        //    location somewhere in the program and make an entry in this table with the
        //    getters and setters.
        // It is easiest to find an existing definition and copy it.
        //
        // A ParameterDefn<T>() takes the following parameters:
        //    -- the text name of the parameter. This is used for console input and ini file.
        //    -- a short text description of the parameter. This shows up in the console listing.
        //    -- a default value
        //    -- a delegate for getting the value
        //    -- a delegate for setting the value
        //    -- an optional delegate to update the value in the world. Most often used to
        //          push the new value to an in-world object.
        //
        // The single letter parameters for the delegates are:
        //    s = BSScene
        //    o = BSPhysObject
        //    v = value (appropriate type)
        private static ParameterDefnBase[] ParameterDefinitions =
        {
            new ParameterDefn<bool>("Active", "If 'true', false then physics is not active",
                false ),
            new ParameterDefn<bool>("UseSeparatePhysicsThread", "If 'true', the physics engine runs independent from the simulator heartbeat",
                false ),
            new ParameterDefn<float>("PhysicsTimeStep", "If separate thread, seconds to simulate each interval",
                0.089f ),

            new ParameterDefn<bool>("MeshSculptedPrim", "Whether to create meshes for sculpties",
                true,
                (s) => { return ShouldMeshSculptedPrim; },
                (s,v) => { ShouldMeshSculptedPrim = v; } ),
            new ParameterDefn<bool>("ForceSimplePrimMeshing", "If true, only use primitive meshes for objects",
                false,
                (s) => { return ShouldForceSimplePrimMeshing; },
                (s,v) => { ShouldForceSimplePrimMeshing = v; } ),
            new ParameterDefn<bool>("UseHullsForPhysicalObjects", "If true, create hulls for physical objects",
                true,
                (s) => { return ShouldUseHullsForPhysicalObjects; },
                (s,v) => { ShouldUseHullsForPhysicalObjects = v; } ),
            new ParameterDefn<bool>("ShouldRemoveZeroWidthTriangles", "If true, remove degenerate triangles from meshes",
                true ),
            new ParameterDefn<bool>("ShouldUseBulletHACD", "If true, use the Bullet version of HACD",
                false ),
            new ParameterDefn<bool>("ShouldUseSingleConvexHullForPrims", "If true, use a single convex hull shape for physical prims",
                true ),
            new ParameterDefn<bool>("ShouldUseGImpactShapeForPrims", "If true, use a GImpact shape for prims with cuts and twists",
                false ),
            new ParameterDefn<bool>("ShouldUseAssetHulls", "If true, use hull if specified in the mesh asset info",
                true ),

            new ParameterDefn<int>("CrossingFailuresBeforeOutOfBounds", "How forgiving we are about getting into adjactent regions",
                5 ),
            new ParameterDefn<float>("UpdateVelocityChangeThreshold", "Change in updated velocity required before reporting change to simulator",
                0.1f ),

            new ParameterDefn<float>("MeshLevelOfDetail", "Level of detail to render meshes (32, 16, 8 or 4. 32=most detailed)",
                32f,
                (s) => { return MeshLOD; },
                (s,v) => { MeshLOD = v; } ),
            new ParameterDefn<float>("MeshLevelOfDetailCircular", "Level of detail for prims with circular cuts or shapes",
                32f,
                (s) => { return MeshCircularLOD; },
                (s,v) => { MeshCircularLOD = v; } ),
            new ParameterDefn<float>("MeshLevelOfDetailMegaPrimThreshold", "Size (in meters) of a mesh before using MeshMegaPrimLOD",
                10f,
                (s) => { return MeshMegaPrimThreshold; },
                (s,v) => { MeshMegaPrimThreshold = v; } ),
            new ParameterDefn<float>("MeshLevelOfDetailMegaPrim", "Level of detail to render meshes larger than threshold meters",
                32f,
                (s) => { return MeshMegaPrimLOD; },
                (s,v) => { MeshMegaPrimLOD = v; } ),
            new ParameterDefn<float>("SculptLevelOfDetail", "Level of detail to render sculpties (32, 16, 8 or 4. 32=most detailed)",
                32f,
                (s) => { return SculptLOD; },
                (s,v) => { SculptLOD = v; } ),

            new ParameterDefn<int>("MaxSubStep", "In simulation step, maximum number of substeps",
                10,
                (s) => { return s.m_maxSubSteps; },
                (s,v) => { s.m_maxSubSteps = (int)v; } ),
            new ParameterDefn<float>("FixedTimeStep", "In simulation step, seconds of one substep (1/60)",
                1f / 60f,
                (s) => { return s.m_fixedTimeStep; },
                (s,v) => { s.m_fixedTimeStep = v; } ),
            new ParameterDefn<float>("NominalFrameRate", "The base frame rate we claim",
                55f,
                (s) => { return s.NominalFrameRate; },
                (s,v) => { s.NominalFrameRate = (int)v; } ),
            new ParameterDefn<int>("MaxCollisionsPerFrame", "Max collisions returned at end of each frame",
                2048,
                (s) => { return s.m_maxCollisionsPerFrame; },
                (s,v) => { s.m_maxCollisionsPerFrame = (int)v; } ),
            new ParameterDefn<int>("MaxUpdatesPerFrame", "Max updates returned at end of each frame",
                8000,
                (s) => { return s.m_maxUpdatesPerFrame; },
                (s,v) => { s.m_maxUpdatesPerFrame = (int)v; } ),

            new ParameterDefn<float>("MinObjectMass", "Minimum object mass (0.0001)",
                0.0001f,
                (s) => { return MinimumObjectMass; },
                (s,v) => { MinimumObjectMass = v; } ),
            new ParameterDefn<float>("MaxObjectMass", "Maximum object mass (10000.01)",
                10000.01f,
                (s) => { return MaximumObjectMass; },
                (s,v) => { MaximumObjectMass = v; } ),
            new ParameterDefn<float>("MaxLinearVelocity", "Maximum velocity magnitude that can be assigned to an object",
                1000.0f,
                (s) => { return MaxLinearVelocity; },
                (s,v) => { MaxLinearVelocity = v; MaxLinearVelocitySquared = v * v; } ),
            new ParameterDefn<float>("MaxAngularVelocity", "Maximum rotational velocity magnitude that can be assigned to an object",
                1000.0f,
                (s) => { return MaxAngularVelocity; },
                (s,v) => { MaxAngularVelocity = v;  MaxAngularVelocitySquared = v * v; } ),
            // LL documentation says thie number should be 20f for llApplyImpulse and 200f for llRezObject
            new ParameterDefn<float>("MaxAddForceMagnitude", "Maximum force that can be applied by llApplyImpulse (SL says 20f)",
                20000.0f,
                (s) => { return MaxAddForceMagnitude; },
                (s,v) => { MaxAddForceMagnitude = v; MaxAddForceMagnitudeSquared = v * v; } ),
            // Density is passed around as 100kg/m3. This scales that to 1kg/m3.
            // Reduce by power of 100 because Bullet doesn't seem to handle objects with large mass very well
            new ParameterDefn<float>("DensityScaleFactor", "Conversion for simulator/viewer density (100kg/m3) to physical density (1kg/m3)",
                0.01f ),

            new ParameterDefn<float>("PID_D", "Derivitive factor for motion smoothing",
                2200f ),
            new ParameterDefn<float>("PID_P", "Parameteric factor for motion smoothing",
                900f ),

            new ParameterDefn<float>("DefaultFriction", "Friction factor used on new objects",
                0.2f,
                (s) => { return DefaultFriction; },
                (s,v) => { DefaultFriction = v; s.UnmanagedParams[0].defaultFriction = v; } ),
            // For historical reasons, the viewer and simulator multiply the density by 100
            new ParameterDefn<float>("DefaultDensity", "Density for new objects" ,
                1000.0006836f,  // Aluminum g/cm3 * 100
                (s) => { return DefaultDensity; },
                (s,v) => { DefaultDensity = v; s.UnmanagedParams[0].defaultDensity = v; } ),
            new ParameterDefn<float>("DefaultRestitution", "Bouncyness of an object" ,
                0f,
                (s) => { return DefaultRestitution; },
                (s,v) => { DefaultRestitution = v; s.UnmanagedParams[0].defaultRestitution = v; } ),
            new ParameterDefn<float>("CollisionMargin", "Margin around objects before collisions are calculated (must be zero!)",
                0.04f,
                (s) => { return CollisionMargin; },
                (s,v) => { CollisionMargin = v; s.UnmanagedParams[0].collisionMargin = v; } ),
            new ParameterDefn<float>("Gravity", "Vertical force of gravity (negative means down)",
                -9.80665f,
                (s) => { return Gravity; },
                (s,v) => { Gravity = v; s.UnmanagedParams[0].gravity = v; },
                (s,o) => { s.PE.SetGravity(o.PhysBody, new Vector3(0f,0f,Gravity)); } ),


            new ParameterDefn<float>("LinearDamping", "Factor to damp linear movement per second (0.0 - 1.0)",
                0f,
                (s) => { return LinearDamping; },
                (s,v) => { LinearDamping = v; },
                (s,o) => { s.PE.SetDamping(o.PhysBody, LinearDamping, AngularDamping); } ),
            new ParameterDefn<float>("AngularDamping", "Factor to damp angular movement per second (0.0 - 1.0)",
                0f,
                (s) => { return AngularDamping; },
                (s,v) => { AngularDamping = v; },
                (s,o) => { s.PE.SetDamping(o.PhysBody, LinearDamping, AngularDamping); } ),
            new ParameterDefn<float>("DeactivationTime", "Seconds before considering an object potentially static",
                0.2f,
                (s) => { return DeactivationTime; },
                (s,v) => { DeactivationTime = v; },
                (s,o) => { s.PE.SetDeactivationTime(o.PhysBody, DeactivationTime); } ),
            new ParameterDefn<float>("LinearSleepingThreshold", "Seconds to measure linear movement before considering static",
                0.8f,
                (s) => { return LinearSleepingThreshold; },
                (s,v) => { LinearSleepingThreshold = v;},
                (s,o) => { s.PE.SetSleepingThresholds(o.PhysBody, LinearSleepingThreshold, AngularSleepingThreshold); } ),
            new ParameterDefn<float>("AngularSleepingThreshold", "Seconds to measure angular movement before considering static",
                1.0f,
                (s) => { return AngularSleepingThreshold; },
                (s,v) => { AngularSleepingThreshold = v;},
                (s,o) => { s.PE.SetSleepingThresholds(o.PhysBody, LinearSleepingThreshold, AngularSleepingThreshold); } ),
            new ParameterDefn<float>("CcdMotionThreshold", "Continuious collision detection threshold (0 means no CCD)" ,
                0.0f,     // set to zero to disable
                (s) => { return CcdMotionThreshold; },
                (s,v) => { CcdMotionThreshold = v;},
                (s,o) => { s.PE.SetCcdMotionThreshold(o.PhysBody, CcdMotionThreshold); } ),
            new ParameterDefn<float>("CcdSweptSphereRadius", "Continuious collision detection test radius" ,
                0.2f,
                (s) => { return CcdSweptSphereRadius; },
                (s,v) => { CcdSweptSphereRadius = v;},
                (s,o) => { s.PE.SetCcdSweptSphereRadius(o.PhysBody, CcdSweptSphereRadius); } ),
            new ParameterDefn<float>("ContactProcessingThreshold", "Distance above which contacts can be discarded (0 means no discard)" ,
                0.0f,
                (s) => { return ContactProcessingThreshold; },
                (s,v) => { ContactProcessingThreshold = v;},
                (s,o) => { s.PE.SetContactProcessingThreshold(o.PhysBody, ContactProcessingThreshold); } ),

            new ParameterDefn<float>("TerrainImplementation", "Type of shape to use for terrain (0=heightmap, 1=mesh)",
                (float)BSTerrainPhys.TerrainImplementation.Heightmap ),
            new ParameterDefn<int>("TerrainMeshMagnification", "Number of times the 256x256 heightmap is multiplied to create the terrain mesh" ,
                2 ),
            new ParameterDefn<float>("TerrainGroundPlane", "Altitude of ground plane used to keep things from falling to infinity" ,
                -500.0f ),
            new ParameterDefn<float>("TerrainFriction", "Factor to reduce movement against terrain surface" ,
                0.3f ),
            new ParameterDefn<float>("TerrainHitFraction", "Distance to measure hit collisions" ,
                0.8f ),
            new ParameterDefn<float>("TerrainRestitution", "Bouncyness" ,
                0f ),
            new ParameterDefn<float>("TerrainContactProcessingThreshold", "Distance from terrain to stop processing collisions" ,
                0.0f ),
            new ParameterDefn<float>("TerrainCollisionMargin", "Margin where collision checking starts" ,
                0.04f ),

            new ParameterDefn<bool>("AvatarToAvatarCollisionsByDefault", "Should avatars collide with other avatars by default?",
                true),
            new ParameterDefn<float>("AvatarFriction", "Factor to reduce movement against an avatar. Changed on avatar recreation.",
                0.2f ),
            new ParameterDefn<float>("AvatarStandingFriction", "Avatar friction when standing. Changed on avatar recreation.",
                0.95f ),
            new ParameterDefn<float>("AvatarWalkVelocityFactor", "Speed multiplier if avatar is walking",
                1.0f ),
            new ParameterDefn<float>("AvatarAlwaysRunFactor", "Speed multiplier if avatar is set to always run",
                1.3f ),
                // For historical reasons, density is reported  * 100
            new ParameterDefn<float>("AvatarDensity", "Density of an avatar. Changed on avatar recreation. Scaled times 100.",
                350f) ,    // 3.5 * 100
            new ParameterDefn<float>("AvatarRestitution", "Bouncyness. Changed on avatar recreation.",
                0f ),
            new ParameterDefn<int>("AvatarShape", "Code for avatar physical shape: 0:capsule, 1:cube, 2:ovoid, 2:mesh",
                BSShapeCollection.AvatarShapeCube ) ,
            new ParameterDefn<float>("AvatarCapsuleWidth", "The distance between the sides of the avatar capsule",
                0.6f ) ,
            new ParameterDefn<float>("AvatarCapsuleDepth", "The distance between the front and back of the avatar capsule",
                0.45f ),
            new ParameterDefn<float>("AvatarCapsuleHeight", "Default height of space around avatar",
                1.5f ),
            new ParameterDefn<bool>("AvatarUseBefore09SizeComputation", "Use the old fudge method of computing avatar capsule size",
                true ),
            new ParameterDefn<float>("AvatarHeightLowFudge", "A fudge factor to make small avatars stand on the ground",
                0f ),
            new ParameterDefn<float>("AvatarHeightMidFudge", "A fudge distance to adjust average sized avatars to be standing on ground",
                0f ),
            new ParameterDefn<float>("AvatarHeightHighFudge", "A fudge factor to make tall avatars stand on the ground",
                0f ),
            new ParameterDefn<float>("AvatarFlyingGroundMargin", "Meters avatar is kept above the ground when flying",
                5f ),
            new ParameterDefn<float>("AvatarFlyingGroundUpForce", "Upward force applied to the avatar to keep it at flying ground margin",
                2.0f ),
            new ParameterDefn<int>("AvatarAddForceFrames", "Frames to allow AddForce to apply before checking for stationary",
                10 ),
            new ParameterDefn<float>("AvatarTerminalVelocity", "Terminal Velocity of falling avatar",
                -54.0f ),
            new ParameterDefn<float>("AvatarContactProcessingThreshold", "Distance from capsule to check for collisions",
                0.1f ),
            new ParameterDefn<float>("AvatarAddForcePushFactor", "BSCharacter.AddForce is multiplied by this and mass to be like other physics engines",
                0.315f ),
            new ParameterDefn<float>("AvatarStopZeroThreshold", "Movement velocity below which avatar is assumed to be stopped",
                0.45f,
                (s) => { return (float)AvatarStopZeroThreshold; },
                (s,v) => { AvatarStopZeroThreshold = v; AvatarStopZeroThresholdSquared = v * v; } ),
            new ParameterDefn<float>("AvatarBelowGroundUpCorrectionMeters", "Meters to move avatar up if it seems to be below ground",
                1.0f ),
            new ParameterDefn<int>("AvatarJumpFrames", "Number of frames to allow jump forces. Changes jump height.",
                4 ),
            new ParameterDefn<float>("AvatarStepHeight", "Height of a step obstacle to consider step correction",
                0.999f ) ,
            new ParameterDefn<float>("AvatarStepAngle", "The angle (in radians) for a vertical surface to be considered a step",
                0.3f ) ,
            new ParameterDefn<float>("AvatarStepGroundFudge", "Fudge factor subtracted from avatar base when comparing collision height",
                0.1f ) ,
            new ParameterDefn<float>("AvatarStepApproachFactor", "Factor to control angle of approach to step (0=straight on)",
                2f ),
            new ParameterDefn<float>("AvatarStepForceFactor", "Controls the amount of force up applied to step up onto a step",
                0f ),
            new ParameterDefn<float>("AvatarStepUpCorrectionFactor", "Multiplied by height of step collision to create up movement at step",
                0.8f ),
            new ParameterDefn<int>("AvatarStepSmoothingSteps", "Number of frames after a step collision that we continue walking up stairs",
                1 ),

            new ParameterDefn<float>("VehicleMaxLinearVelocity", "Maximum velocity magnitude that can be assigned to a vehicle",
                1000.0f,
                (s) => { return (float)VehicleMaxLinearVelocity; },
                (s,v) => { VehicleMaxLinearVelocity = v; VehicleMaxLinearVelocitySquared = v * v; } ),
            new ParameterDefn<float>("VehicleMinLinearVelocity", "Maximum velocity magnitude that can be assigned to a vehicle",
                0.001f,
                (s) => { return (float)VehicleMinLinearVelocity; },
                (s,v) => { VehicleMinLinearVelocity = v; VehicleMinLinearVelocitySquared = v * v; } ),
            new ParameterDefn<float>("VehicleMaxAngularVelocity", "Maximum rotational velocity magnitude that can be assigned to a vehicle",
                12.0f,
                (s) => { return (float)VehicleMaxAngularVelocity; },
                (s,v) => { VehicleMaxAngularVelocity = v; VehicleMaxAngularVelocitySq = v * v; } ),
            new ParameterDefn<float>("VehicleAngularDamping", "Factor to damp vehicle angular movement per second (0.0 - 1.0)",
                0.0f ),
            new ParameterDefn<Vector3>("VehicleLinearFactor", "Fraction of physical linear changes applied to vehicle (<0,0,0> to <1,1,1>)",
                new Vector3(1f, 1f, 1f) ),
            new ParameterDefn<Vector3>("VehicleAngularFactor", "Fraction of physical angular changes applied to vehicle (<0,0,0> to <1,1,1>)",
                new Vector3(1f, 1f, 1f) ),
            new ParameterDefn<Vector3>("VehicleInertiaFactor", "Fraction of physical inertia applied (<0,0,0> to <1,1,1>)",
                new Vector3(1f, 1f, 1f) ),
            new ParameterDefn<float>("VehicleFriction", "Friction of vehicle on the ground (0.0 - 1.0)",
                0.0f ),
            new ParameterDefn<float>("VehicleRestitution", "Bouncyness factor for vehicles (0.0 - 1.0)",
                0.0f ),
            new ParameterDefn<float>("VehicleGroundGravityFudge", "Factor to multiply gravity if a ground vehicle is probably on the ground (0.0 - 1.0)",
                0.2f ),
            new ParameterDefn<float>("VehicleAngularBankingTimescaleFudge", "Factor to multiple angular banking timescale. Tune to increase realism.",
                60.0f ),
            new ParameterDefn<bool>("VehicleEnableLinearDeflection", "Turn on/off vehicle linear deflection effect",
                true ),
            new ParameterDefn<bool>("VehicleLinearDeflectionNotCollidingNoZ", "Turn on/off linear deflection Z effect on non-colliding vehicles",
                true ),
            new ParameterDefn<bool>("VehicleEnableAngularVerticalAttraction", "Turn on/off vehicle angular vertical attraction effect",
                true ),
            new ParameterDefn<int>("VehicleAngularVerticalAttractionAlgorithm", "Select vertical attraction algo. You need to look at the source.",
                0 ),
            new ParameterDefn<bool>("VehicleEnableAngularDeflection", "Turn on/off vehicle angular deflection effect",
                true ),
            new ParameterDefn<bool>("VehicleEnableAngularBanking", "Turn on/off vehicle angular banking effect",
                true ),

            new ParameterDefn<float>("MaxPersistantManifoldPoolSize", "Number of manifolds pooled (0 means default of 4096)",
                0f,
                (s) => { return MaxPersistantManifoldPoolSize; },
                (s,v) => { MaxPersistantManifoldPoolSize = v; s.UnmanagedParams[0].maxPersistantManifoldPoolSize = v; } ),
            new ParameterDefn<float>("MaxCollisionAlgorithmPoolSize", "Number of collisions pooled (0 means default of 4096)",
                0f,
                (s) => { return MaxCollisionAlgorithmPoolSize; },
                (s,v) => { MaxCollisionAlgorithmPoolSize = v; s.UnmanagedParams[0].maxCollisionAlgorithmPoolSize = v; } ),
            new ParameterDefn<bool>("ShouldDisableContactPoolDynamicAllocation", "Enable to allow large changes in object count",
                false,
                (s) => { return ShouldDisableContactPoolDynamicAllocation; },
                (s,v) => { ShouldDisableContactPoolDynamicAllocation = v;
                            s.UnmanagedParams[0].shouldDisableContactPoolDynamicAllocation = NumericBool(v); } ),
            new ParameterDefn<bool>("ShouldForceUpdateAllAabbs", "Enable to recomputer AABBs every simulator step",
                false,
                (s) => { return ShouldForceUpdateAllAabbs; },
                (s,v) => { ShouldForceUpdateAllAabbs = v; s.UnmanagedParams[0].shouldForceUpdateAllAabbs = NumericBool(v); } ),
            new ParameterDefn<bool>("ShouldRandomizeSolverOrder", "Enable for slightly better stacking interaction",
                true,
                (s) => { return ShouldRandomizeSolverOrder; },
                (s,v) => { ShouldRandomizeSolverOrder = v; s.UnmanagedParams[0].shouldRandomizeSolverOrder = NumericBool(v); } ),
            new ParameterDefn<bool>("ShouldSplitSimulationIslands", "Enable splitting active object scanning islands",
                true,
                (s) => { return ShouldSplitSimulationIslands; },
                (s,v) => { ShouldSplitSimulationIslands = v; s.UnmanagedParams[0].shouldSplitSimulationIslands = NumericBool(v); } ),
            new ParameterDefn<bool>("ShouldEnableFrictionCaching", "Enable friction computation caching",
                true,
                (s) => { return ShouldEnableFrictionCaching; },
                (s,v) => { ShouldEnableFrictionCaching = v; s.UnmanagedParams[0].shouldEnableFrictionCaching = NumericBool(v); } ),
            new ParameterDefn<float>("NumberOfSolverIterations", "Number of internal iterations (0 means default)",
                0f,     // zero says use Bullet default
                (s) => { return NumberOfSolverIterations; },
                (s,v) => { NumberOfSolverIterations = v; s.UnmanagedParams[0].numberOfSolverIterations = v; } ),
            new ParameterDefn<bool>("UseSingleSidedMeshes", "Whether to compute collisions based on single sided meshes.",
                true,
                (s) => { return UseSingleSidedMeshes; },
                (s,v) => { UseSingleSidedMeshes = v; s.UnmanagedParams[0].useSingleSidedMeshes = NumericBool(v); } ),
            new ParameterDefn<float>("GlobalContactBreakingThreshold", "Amount of shape radius before breaking a collision contact (0 says Bullet default (0.2))",
                0f,
                (s) => { return GlobalContactBreakingThreshold; },
                (s,v) => { GlobalContactBreakingThreshold = v; s.UnmanagedParams[0].globalContactBreakingThreshold = v; } ),
            new ParameterDefn<float>("PhysicsUnmanLoggingFrames", "If non-zero, frames between output of detailed unmanaged physics statistics",
                0f,
                (s) => { return PhysicsUnmanLoggingFrames; },
                (s,v) => { PhysicsUnmanLoggingFrames = v; s.UnmanagedParams[0].physicsLoggingFrames = v; } ),

            new ParameterDefn<int>("CSHullMaxDepthSplit", "CS impl: max depth to split for hull. 1-10 but > 7 is iffy",
                7 ),
            new ParameterDefn<int>("CSHullMaxDepthSplitForSimpleShapes", "CS impl: max depth setting for simple prim shapes",
                2 ),
            new ParameterDefn<float>("CSHullConcavityThresholdPercent", "CS impl: concavity threshold percent (0-20)",
                5f ),
            new ParameterDefn<float>("CSHullVolumeConservationThresholdPercent", "percent volume conservation to collapse hulls (0-30)",
                5f ),
            new ParameterDefn<int>("CSHullMaxVertices", "CS impl: maximum number of vertices in output hulls. Keep < 50.",
                32 ),
            new ParameterDefn<float>("CSHullMaxSkinWidth", "CS impl: skin width to apply to output hulls.",
                0f ),

            new ParameterDefn<float>("BHullMaxVerticesPerHull", "Bullet impl: max number of vertices per created hull",
                200f ),
            new ParameterDefn<float>("BHullMinClusters", "Bullet impl: minimum number of hulls to create per mesh",
                10f ),
            new ParameterDefn<float>("BHullCompacityWeight", "Bullet impl: weight factor for how compact to make hulls",
                20f ),
            new ParameterDefn<float>("BHullVolumeWeight", "Bullet impl: weight factor for volume in created hull",
                0.1f ),
            new ParameterDefn<float>("BHullConcavity", "Bullet impl: weight factor for how convex a created hull can be",
                10f ),
            new ParameterDefn<bool>("BHullAddExtraDistPoints", "Bullet impl: whether to add extra vertices for long distance vectors",
                true ),
            new ParameterDefn<bool>("BHullAddNeighboursDistPoints", "Bullet impl: whether to add extra vertices between neighbor hulls",
                true ),
            new ParameterDefn<bool>("BHullAddFacesPoints", "Bullet impl: whether to add extra vertices to break up hull faces",
                true ),
            new ParameterDefn<bool>("BHullShouldAdjustCollisionMargin", "Bullet impl: whether to shrink resulting hulls to account for collision margin",
                false ),

            new ParameterDefn<float>("WhichHACD", "zero if Bullet HACD, non-zero says VHACD",
                0f ),
            new ParameterDefn<float>("VHACDresolution", "max number of voxels generated during voxelization stage",
                100000f ),
            new ParameterDefn<float>("VHACDdepth", "max number of clipping stages",
                20f ),
            new ParameterDefn<float>("VHACDconcavity", "maximum concavity",
                0.0025f ),
            new ParameterDefn<float>("VHACDplaneDownsampling", "granularity of search for best clipping plane",
                4f ),
            new ParameterDefn<float>("VHACDconvexHullDownsampling", "precision of hull gen process",
                4f ),
            new ParameterDefn<float>("VHACDalpha", "bias toward clipping along symmetry planes",
                0.05f ),
            new ParameterDefn<float>("VHACDbeta", "bias toward clipping along revolution axis",
                0.05f ),
            new ParameterDefn<float>("VHACDgamma", "max concavity when merging",
                0.00125f ),
            new ParameterDefn<float>("VHACDpca", "on/off normalizing mesh before decomp",
                0f ),
            new ParameterDefn<float>("VHACDmode", "0:voxel based, 1: tetrahedron based",
                0f ),
            new ParameterDefn<float>("VHACDmaxNumVerticesPerCH", "max triangles per convex hull",
                64f ),
            new ParameterDefn<float>("VHACDminVolumePerCH", "sampling of generated convex hulls",
                0.0001f ),

            new ParameterDefn<float>("LinksetImplementation", "Type of linkset implementation (0=Constraint, 1=Compound, 2=Manual)",
                (float)BSLinkset.LinksetImplementation.Compound ),
            new ParameterDefn<bool>("LinksetOffsetCenterOfMass", "If 'true', compute linkset center-of-mass and offset linkset position to account for same",
                true ),
            new ParameterDefn<bool>("LinkConstraintUseFrameOffset", "For linksets built with constraints, enable frame offsetFor linksets built with constraints, enable frame offset.",
                false ),
            new ParameterDefn<bool>("LinkConstraintEnableTransMotor", "Whether to enable translational motor on linkset constraints",
                true ),
            new ParameterDefn<float>("LinkConstraintTransMotorMaxVel", "Maximum velocity to be applied by translational motor in linkset constraints",
                5.0f ),
            new ParameterDefn<float>("LinkConstraintTransMotorMaxForce", "Maximum force to be applied by translational motor in linkset constraints",
                0.1f ),
            new ParameterDefn<float>("LinkConstraintCFM", "Amount constraint can be violated. 0=no violation, 1=infinite. Default=0.1",
                0.1f ),
            new ParameterDefn<float>("LinkConstraintERP", "Amount constraint is corrected each tick. 0=none, 1=all. Default = 0.2",
                0.1f ),
            new ParameterDefn<float>("LinkConstraintSolverIterations", "Number of solver iterations when computing constraint. (0 = Bullet default)",
                40 ),

            new ParameterDefn<bool>("UseBulletRaycast", "If 'true', use the raycast function of the Bullet physics engine",
                true ),

            new ParameterDefn<float>("DebugNumber", "A console setable number sometimes used for debugging",
                1.0f ),

            new ParameterDefn<int>("PhysicsMetricFrames", "Frames between outputting detailed phys metrics. (0 is off)",
                0,
                (s) => { return s.PhysicsMetricDumpFrames; },
                (s,v) => { s.PhysicsMetricDumpFrames = v; } ),
            new ParameterDefn<float>("ResetBroadphasePool", "Setting this is any value resets the broadphase collision pool",
                0f,
                (s) => { return 0f; },
                (s,v) => { BSParam.ResetBroadphasePoolTainted(s, v); } ),
            new ParameterDefn<float>("ResetConstraintSolver", "Setting this is any value resets the constraint solver",
                0f,
                (s) => { return 0f; },
                (s,v) => { BSParam.ResetConstraintSolverTainted(s, v); } ),

            new ParameterDefn<string>("VersionLegacyValue", "Version string returned by legacy BulletSim binaries",
                "v0003" ),
            new ParameterDefn<string>("VersionLegacyReplacement", "Value used to replace legacy version number",
                "1.0,2.84" ),
        };

        // Convert a boolean to our numeric true and false values
        public static float NumericBool(bool b)
        {
            return (b ? ConfigurationParameters.numericTrue : ConfigurationParameters.numericFalse);
        }

        // Convert numeric true and false values to a boolean
        public static bool BoolNumeric(float b)
        {
            return (b == ConfigurationParameters.numericTrue ? true : false);
        }

        // Search through the parameter definitions and return the matching
        //    ParameterDefn structure.
        // Case does not matter as names are compared after converting to lower case.
        // Returns 'false' if the parameter is not found.
        internal static bool TryGetParameter(string paramName, out ParameterDefnBase defn)
        {
            bool ret = false;
            ParameterDefnBase foundDefn = null;
            string pName = paramName.ToLower();

            foreach (ParameterDefnBase parm in ParameterDefinitions)
            {
                if (pName == parm.name.ToLower())
                {
                    foundDefn = parm;
                    ret = true;
                    break;
                }
            }
            defn = foundDefn;
            return ret;
        }

        // Pass through the settable parameters and set the default values
        internal static void SetParameterDefaultValues(BSScene physicsScene)
        {
            foreach (ParameterDefnBase parm in ParameterDefinitions)
            {
                parm.AssignDefault(physicsScene);
            }
        }

        // Get user set values out of the ini file.
        internal static void SetParameterConfigurationValues(BSScene physicsScene, IConfig cfg)
        {
            foreach (ParameterDefnBase parm in ParameterDefinitions)
            {
                parm.SetValue(physicsScene, cfg.GetString(parm.name, parm.GetValue(physicsScene)));
            }
        }

        internal static PhysParameterEntry[] SettableParameters = new PhysParameterEntry[1];

        // This creates an array in the correct format for returning the list of
        //    parameters. This is used by the 'list' option of the 'physics' command.
        internal static void BuildParameterTable()
        {
            if (SettableParameters.Length < ParameterDefinitions.Length)
            {
                List<PhysParameterEntry> entries = new List<PhysParameterEntry>();
                for (int ii = 0; ii < ParameterDefinitions.Length; ii++)
                {
                    ParameterDefnBase pd = ParameterDefinitions[ii];
                    entries.Add(new PhysParameterEntry(pd.name, pd.desc));
                }

                // make the list alphabetical for ease of finding anything
                entries.Sort((ppe1, ppe2) => { return ppe1.name.CompareTo(ppe2.name); });

                SettableParameters = entries.ToArray();
            }
        }

        // =====================================================================
        // =====================================================================
        // There are parameters that, when set, cause things to happen in the physics engine.
        // This causes the broadphase collision cache to be cleared.
        private static void ResetBroadphasePoolTainted(BSScene pPhysScene, float v)
        {
            BSScene physScene = pPhysScene;
            physScene.TaintedObject(BSScene.DetailLogZero, "BSParam.ResetBroadphasePoolTainted", delegate()
            {
                physScene.PE.ResetBroadphasePool(physScene.World);
            });
        }

        // This causes the constraint solver cache to be cleared and reset.
        private static void ResetConstraintSolverTainted(BSScene pPhysScene, float v)
        {
            BSScene physScene = pPhysScene;
            physScene.TaintedObject(BSScene.DetailLogZero, "BSParam.ResetConstraintSolver", delegate()
            {
                physScene.PE.ResetConstraintSolver(physScene.World);
            });
        }
    }
}