C# BEPUutilities.Ray类代码示例

        /// <summary>
        /// Computes the intersection, if any, between a ray and the objects in the character's bounding box.
        /// </summary>
        /// <param name="ray">Ray to test.</param>
        /// <param name="length">Length of the ray to use in units of the ray's length.</param>
        /// <param name="earliestHit">Earliest intersection location and information.</param>
        /// <param name="hitObject">Collidable intersected by the ray, if any.</param>
        /// <returns>Whether or not the ray hit anything.</returns>
        public bool RayCast(Ray ray, float length, out RayHit earliestHit, out Collidable hitObject)
        {
            earliestHit = new RayHit();
            earliestHit.T = float.MaxValue;
            hitObject = null;
            foreach (var collidable in characterBody.CollisionInformation.OverlappedCollidables)
            {
                //Check to see if the collidable is hit by the ray.
                float t;
                if (ray.Intersects(ref collidable.boundingBox, out t) && t < length)
                {
                    //Is it an earlier hit than the current earliest?
                    RayHit hit;
                    if (collidable.RayCast(ray, length, SupportRayFilter, out hit) && hit.T < earliestHit.T)
                    {
                        earliestHit = hit;
                        hitObject = collidable;
                    }
                }
            }
            if (earliestHit.T == float.MaxValue)
                return false;
            return true;

        }

 ///<summary>
 /// Tests a ray against the triangle mesh.
 ///</summary>
 ///<param name="ray">Ray to test against the mesh.</param>
 ///<param name="hitCount">Number of hits between the ray and the mesh.</param>
 ///<returns>Whether or not the ray hit the mesh.</returns>
 public bool RayCast(Ray ray, out int hitCount)
 {
     var rayHits = CommonResources.GetRayHitList();
     bool toReturn = RayCast(ray, rayHits);
     hitCount = rayHits.Count;
     CommonResources.GiveBack(rayHits);
     return toReturn;
 }

        /// <summary>
        /// Finds all intersections between the ray and broad phase entries.
        /// </summary>
        /// <param name="ray">Ray to test against the structure.</param>
        /// <param name="maximumLength">Maximum length of the ray in units of the ray's direction's length.</param>
        /// <param name="entries">Entries which have bounding boxes that overlap the ray.</param>
        public bool RayCast(Ray ray, float maximumLength, IList<BroadPhaseEntry> entries)
        {
            if (hierarchy.root != null)
            {
                hierarchy.root.GetOverlaps(ref ray, maximumLength, entries);

                return entries.Count > 0;
            }
            return false;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="from"></param>
        /// <param name="to"></param>
        /// <param name="normal"></param>
        /// <param name="pos"></param>
        /// <returns></returns>
        public bool RayCastAgainstAll( Vector3 from, Vector3 to, out Vector3 normal, out Vector3 pos, out Entity hitEntity, Entity skipEntity = null )
        {
            hitEntity	=	null;
            var dir		=	to - from;
            var dist	=	dir.Length();
            var ndir	=	dir.Normalized();
            Ray ray		=	new Ray( from, ndir );

            normal	= Vector3.Zero;
            pos		= to;

            Func<BroadPhaseEntry, bool> filterFunc = delegate(BroadPhaseEntry bpe)
            {
                if (skipEntity==null) return true;

                ConvexCollidable cc = bpe as ConvexCollidable;
                if (cc==null) return true;

                Entity ent = cc.Entity.Tag as Entity;
                if (ent==null) return true;

                if (ent==skipEntity) return false;

                return true;
            };

            var rcr		= new RayCastResult();
            var bRay	= MathConverter.Convert( ray );

            bool result = physSpace.RayCast( bRay, dist, filterFunc, out rcr );

            if (!result) {
                return false;
            }

            var convex	=	rcr.HitObject as ConvexCollidable;
            normal		=	MathConverter.Convert( rcr.HitData.Normal ).Normalized();
            pos			=	MathConverter.Convert( rcr.HitData.Location );
            hitEntity	=	(convex == null) ? null : convex.Entity.Tag as Entity;

            return true;
        }

 /// <summary>
 /// Tests a ray against the collidable.
 /// </summary>
 /// <param name="ray">Ray to test.</param>
 /// <param name="maximumLength">Maximum length, in units of the ray's direction's length, to test.</param>
 /// <param name="result">Hit data, if any.</param>
 /// <returns>Whether or not the ray hit the entry.</returns>
 public bool RayCast(Ray ray, float maximumLength, out RayCastResult result)
 {
     var outputOverlappedElements = PhysicsResources.GetCollidableList();
     CollidableTree.GetOverlaps(ray, maximumLength, outputOverlappedElements);
     result = new RayCastResult();
     result.HitData.T = float.MaxValue;
     for (int i = 0; i < outputOverlappedElements.Count; ++i)
     {
         RayHit hit;
         if (outputOverlappedElements.Elements[i].RayCast(ray, maximumLength, out hit))
         {
             if (hit.T < result.HitData.T)
             {
                 result.HitData = hit;
                 result.HitObject = outputOverlappedElements.Elements[i];
             }
         }
     }
     PhysicsResources.GiveBack(outputOverlappedElements);
     return result.HitData.T < float.MaxValue;
 }

 /// <summary>
 /// Finds the intersection between the given ray and the given plane.
 /// </summary>
 /// <param name="ray">Ray to test against the plane.</param>
 /// <param name="p">Plane for comparison.</param>
 /// <param name="t">Interval along line to intersection (A + t * AB).</param>
 /// <param name="q">Intersection point.</param>
 /// <returns>Whether or not the line intersects the plane.  If false, the line is parallel to the plane's surface.</returns>
 public static bool GetRayPlaneIntersection(ref Ray ray, ref Plane p, out float t, out Vector3 q)
 {
     float denominator;
     Vector3.Dot(ref p.Normal, ref ray.Direction, out denominator);
     if (denominator < Epsilon && denominator > -Epsilon)
     {
         //Surface of plane and line are parallel (or very close to it).
         q = new Vector3();
         t = float.MaxValue;
         return false;
     }
     float numerator;
     Vector3.Dot(ref p.Normal, ref ray.Position, out numerator);
     t = (p.D - numerator) / denominator;
     //Compute the intersection position.
     Vector3.Multiply(ref ray.Direction, t, out q);
     Vector3.Add(ref ray.Position, ref q, out q);
     return t >= 0;
 }

        /// <summary>
        /// Determines the intersection between a ray and a triangle.
        /// </summary>
        /// <param name="ray">Ray to test.</param>
        /// <param name="maximumLength">Maximum length to travel in units of the direction's length.</param>
        /// <param name="sidedness">Sidedness of the triangle to test.</param>
        /// <param name="a">First vertex of the triangle.</param>
        /// <param name="b">Second vertex of the triangle.</param>
        /// <param name="c">Third vertex of the triangle.</param>
        /// <param name="hit">Hit data of the ray, if any</param>
        /// <returns>Whether or not the ray and triangle intersect.</returns>
        public static bool FindRayTriangleIntersection(ref Ray ray, float maximumLength, TriangleSidedness sidedness, ref Vector3 a, ref Vector3 b, ref Vector3 c, out RayHit hit)
        {
            hit = new RayHit();
            Vector3 ab, ac;
            Vector3.Subtract(ref b, ref a, out ab);
            Vector3.Subtract(ref c, ref a, out ac);

            Vector3.Cross(ref ab, ref ac, out hit.Normal);
            if (hit.Normal.LengthSquared() < Epsilon)
                return false; //Degenerate triangle!

            float d;
            Vector3.Dot(ref ray.Direction, ref hit.Normal, out d);
            d = -d;
            switch (sidedness)
            {
                case TriangleSidedness.DoubleSided:
                    if (d <= 0) //Pointing the wrong way.  Flip the normal.
                    {
                        Vector3.Negate(ref hit.Normal, out hit.Normal);
                        d = -d;
                    }
                    break;
                case TriangleSidedness.Clockwise:
                    if (d <= 0) //Pointing the wrong way.  Can't hit.
                        return false;

                    break;
                case TriangleSidedness.Counterclockwise:
                    if (d >= 0) //Pointing the wrong way.  Can't hit.
                        return false;

                    Vector3.Negate(ref hit.Normal, out hit.Normal);
                    d = -d;
                    break;
            }

            Vector3 ap;
            Vector3.Subtract(ref ray.Position, ref a, out ap);

            Vector3.Dot(ref ap, ref hit.Normal, out hit.T);
            hit.T /= d;
            if (hit.T < 0 || hit.T > maximumLength)
                return false;//Hit is behind origin, or too far away.

            Vector3.Multiply(ref ray.Direction, hit.T, out hit.Location);
            Vector3.Add(ref ray.Position, ref hit.Location, out hit.Location);

            // Compute barycentric coordinates
            Vector3.Subtract(ref hit.Location, ref a, out ap);
            float ABdotAB, ABdotAC, ABdotAP;
            float ACdotAC, ACdotAP;
            Vector3.Dot(ref ab, ref ab, out ABdotAB);
            Vector3.Dot(ref ab, ref ac, out ABdotAC);
            Vector3.Dot(ref ab, ref ap, out ABdotAP);
            Vector3.Dot(ref ac, ref ac, out ACdotAC);
            Vector3.Dot(ref ac, ref ap, out ACdotAP);

            float denom = 1 / (ABdotAB * ACdotAC - ABdotAC * ABdotAC);
            float u = (ACdotAC * ABdotAP - ABdotAC * ACdotAP) * denom;
            float v = (ABdotAB * ACdotAP - ABdotAC * ABdotAP) * denom;

            return (u >= -Toolbox.BigEpsilon) && (v >= -Toolbox.BigEpsilon) && (u + v <= 1 + Toolbox.BigEpsilon);

        }

        /// <summary>
        /// Determines if a ray intersects any object in the character's bounding box.
        /// </summary>
        /// <param name="ray">Ray to test.</param>
        /// <param name="length">Length of the ray to use in units of the ray's length.</param>
        /// <returns>Whether or not the ray hit anything.</returns>
        public bool RayCastHitAnything(ref Ray ray, float length)
        {
            foreach (var collidable in characterBody.CollisionInformation.OverlappedCollidables)
            {
                //Check to see if the collidable is hit by the ray.
                float t;
                if (ray.Intersects(ref collidable.boundingBox, out t) && t < length)
                {
                    RayHit hit;
                    if (collidable.RayCast(ray, length, SupportRayFilter, out hit))
                    {
                        return true;
                    }
                }
            }
            return false;

        }

 bool TryDownCast(ref Ray ray, float length, out bool hasTraction, out SupportRayData supportRayData)
 {
     RayHit earliestHit;
     Collidable earliestHitObject;
     supportRayData = new SupportRayData();
     hasTraction = false;
     if (QueryManager.RayCast(ray, length, out earliestHit, out earliestHitObject))
     {
         float lengthSquared = earliestHit.Normal.LengthSquared();
         if (lengthSquared < Toolbox.Epsilon)
         {
             //Don't try to continue if the support ray is stuck in something.
             return false;
         }
         Vector3Ex.Divide(ref earliestHit.Normal, (float)Math.Sqrt(lengthSquared), out earliestHit.Normal);
         //A collidable was hit!  It's a support, but does it provide traction?
         earliestHit.Normal.Normalize();
         float dot;
         Vector3Ex.Dot(ref ray.Direction, ref earliestHit.Normal, out dot);
         if (dot < 0)
         {
             //Calibrate the normal so it always faces the same direction relative to the body.
             Vector3Ex.Negate(ref earliestHit.Normal, out earliestHit.Normal);
             dot = -dot;
         }
         //This down cast is only used for finding supports and traction, not for finding side contacts.
         //If the detected normal is too steep, toss it out.
         if (dot > ContactCategorizer.TractionThreshold)
         {
             //It has traction!
             hasTraction = true;
             supportRayData = new SupportRayData { HitData = earliestHit, HitObject = earliestHitObject, HasTraction = true };
         }
         else if (dot > ContactCategorizer.SupportThreshold)
             supportRayData = new SupportRayData { HitData = earliestHit, HitObject = earliestHitObject };
         else
             return false; //Too steep! Toss it out.
         return true;
     }
     return false;
 }

 /// <summary>
 /// Tests a ray against the entry.
 /// </summary>
 /// <param name="ray">Ray to test.</param>
 /// <param name="maximumLength">Maximum length, in units of the ray's direction's length, to test.</param>
 /// <param name="filter">Test to apply to the entry. If it returns true, the entry is processed, otherwise the entry is ignored. If a collidable hierarchy is present
 /// in the entry, this filter will be passed into inner ray casts.</param>
 /// <param name="rayHit">Hit location of the ray on the entry, if any.</param>
 /// <returns>Whether or not the ray hit the entry.</returns>
 public virtual bool RayCast(Ray ray, float maximumLength, Func<BroadPhaseEntry, bool> filter, out RayHit rayHit)
 {
     if (filter(this))
         return RayCast(ray, maximumLength, out rayHit);
     rayHit = new RayHit();
     return false;
 }

        /// <summary>
        /// Tests a ray against the entry.
        /// </summary>
        /// <param name="ray">Ray to test.</param>
        /// <param name="maximumLength">Maximum length, in units of the ray's direction's length, to test.</param>
        /// <param name="rayHit">Hit location of the ray on the entry, if any.</param>
        /// <returns>Whether or not the ray hit the entry.</returns>
        public override bool RayCast(Ray ray, float maximumLength, out RayHit rayHit)
        {
            //Put the ray into local space.
            Ray localRay;
            Matrix3x3 orientation;
            Matrix3x3.CreateFromQuaternion(ref worldTransform.Orientation, out orientation);
            Matrix3x3.TransformTranspose(ref ray.Direction, ref orientation, out localRay.Direction);
            Vector3.Subtract(ref ray.Position, ref worldTransform.Position, out localRay.Position);
            Matrix3x3.TransformTranspose(ref localRay.Position, ref orientation, out localRay.Position);

            if (Shape.solidity == MobileMeshSolidity.Solid)
            {
                //Find all hits.  Use the count to determine the ray started inside or outside.
                //If it starts inside and we're in 'solid' mode, then return the ray start.
                //The raycast must be of infinite length at first.  This allows it to determine
                //if it is inside or outside.
                if (Shape.IsLocalRayOriginInMesh(ref localRay, out rayHit))
                {
                    //It was inside!
                    rayHit = new RayHit() { Location = ray.Position, Normal = Vector3.Zero, T = 0 };
                    return true;

                }
                else
                {
                    if (rayHit.T < maximumLength)
                    {
                        //Transform the hit into world space.
                        Vector3.Multiply(ref ray.Direction, rayHit.T, out rayHit.Location);
                        Vector3.Add(ref rayHit.Location, ref ray.Position, out rayHit.Location);
                        Matrix3x3.Transform(ref rayHit.Normal, ref orientation, out rayHit.Normal);
                    }
                    else
                    {
                        //The hit was too far away, or there was no hit (in which case T would be float.MaxValue).
                        return false;
                    }
                    return true;
                }
            }
            else
            {
                //Just do a normal raycast since the object isn't solid.
                TriangleSidedness sidedness;
                switch (Shape.solidity)
                {
                    case MobileMeshSolidity.Clockwise:
                        sidedness = TriangleSidedness.Clockwise;
                        break;
                    case MobileMeshSolidity.Counterclockwise:
                        sidedness = TriangleSidedness.Counterclockwise;
                        break;
                    default:
                        sidedness = TriangleSidedness.DoubleSided;
                        break;
                }
                if (Shape.TriangleMesh.RayCast(localRay, maximumLength, sidedness, out rayHit))
                {
                    //Transform the hit into world space.
                    Vector3.Multiply(ref ray.Direction, rayHit.T, out rayHit.Location);
                    Vector3.Add(ref rayHit.Location, ref ray.Position, out rayHit.Location);
                    Matrix3x3.Transform(ref rayHit.Normal, ref orientation, out rayHit.Normal);
                    return true;
                }
            }
            rayHit = new RayHit();
            return false;
        }

        /// <summary>
        /// Gets the intersection between the convex shape and the ray.
        /// </summary>
        /// <param name="ray">Ray to test.</param>
        /// <param name="transform">Transform of the convex shape.</param>
        /// <param name="maximumLength">Maximum distance to travel in units of the ray direction's length.</param>
        /// <param name="hit">Ray hit data, if any.</param>
        /// <returns>Whether or not the ray hit the target.</returns>
        public override bool RayTest(ref Ray ray, ref RigidTransform transform, float maximumLength, out RayHit hit)
        {
            //Put the ray into local space.
            Quaternion conjugate;
            Quaternion.Conjugate(ref transform.Orientation, out conjugate);
            Ray localRay;
            Vector3.Subtract(ref ray.Position, ref transform.Position, out localRay.Position);
            Quaternion.Transform(ref localRay.Position, ref conjugate, out localRay.Position);
            Quaternion.Transform(ref ray.Direction, ref conjugate, out localRay.Direction);

            //Check for containment.
            if (localRay.Position.Y >= -halfHeight && localRay.Position.Y <= halfHeight && localRay.Position.X * localRay.Position.X + localRay.Position.Z * localRay.Position.Z <= radius * radius)
            {
                //It's inside!
                hit.T = 0;
                hit.Location = localRay.Position;
                hit.Normal = new Vector3(hit.Location.X, 0, hit.Location.Z);
                float normalLengthSquared = hit.Normal.LengthSquared();
                if (normalLengthSquared > 1e-9f)
                    Vector3.Divide(ref hit.Normal, (float)Math.Sqrt(normalLengthSquared), out hit.Normal);
                else
                    hit.Normal = new Vector3();
                //Pull the hit into world space.
                Quaternion.Transform(ref hit.Normal, ref transform.Orientation, out hit.Normal);
                RigidTransform.Transform(ref hit.Location, ref transform, out hit.Location);
                return true;
            }

            //Project the ray direction onto the plane where the cylinder is a circle.
            //The projected ray is then tested against the circle to compute the time of impact.
            //That time of impact is used to compute the 3d hit location.
            Vector2 planeDirection = new Vector2(localRay.Direction.X, localRay.Direction.Z);
            float planeDirectionLengthSquared = planeDirection.LengthSquared();

            if (planeDirectionLengthSquared < Toolbox.Epsilon)
            {
                //The ray is nearly parallel with the axis.
                //Skip the cylinder-sides test.  We're either inside the cylinder and won't hit the sides, or we're outside
                //and won't hit the sides.  
                if (localRay.Position.Y > halfHeight)
                    goto upperTest;
                if (localRay.Position.Y < -halfHeight)
                    goto lowerTest;


                hit = new RayHit();
                return false;

            }
            Vector2 planeOrigin = new Vector2(localRay.Position.X, localRay.Position.Z);
            float dot;
            Vector2.Dot(ref planeDirection, ref planeOrigin, out dot);
            float closestToCenterT = -dot / planeDirectionLengthSquared;

            Vector2 closestPoint;
            Vector2.Multiply(ref planeDirection, closestToCenterT, out closestPoint);
            Vector2.Add(ref planeOrigin, ref closestPoint, out closestPoint);
            //How close does the ray come to the circle?
            float squaredDistance = closestPoint.LengthSquared();
            if (squaredDistance > radius * radius)
            {
                //It's too far!  The ray cannot possibly hit the capsule.
                hit = new RayHit();
                return false;
            }



            //With the squared distance, compute the distance backward along the ray from the closest point on the ray to the axis.
            float backwardsDistance = radius * (float)Math.Sqrt(1 - squaredDistance / (radius * radius));
            float tOffset = backwardsDistance / (float)Math.Sqrt(planeDirectionLengthSquared);

            hit.T = closestToCenterT - tOffset;

            //Compute the impact point on the infinite cylinder in 3d local space.
            Vector3.Multiply(ref localRay.Direction, hit.T, out hit.Location);
            Vector3.Add(ref hit.Location, ref localRay.Position, out hit.Location);

            //Is it intersecting the cylindrical portion of the capsule?
            if (hit.Location.Y <= halfHeight && hit.Location.Y >= -halfHeight && hit.T < maximumLength)
            {
                //Yup!
                hit.Normal = new Vector3(hit.Location.X, 0, hit.Location.Z);
                float normalLengthSquared = hit.Normal.LengthSquared();
                if (normalLengthSquared > 1e-9f)
                    Vector3.Divide(ref hit.Normal, (float)Math.Sqrt(normalLengthSquared), out hit.Normal);
                else
                    hit.Normal = new Vector3();
                //Pull the hit into world space.
                Quaternion.Transform(ref hit.Normal, ref transform.Orientation, out hit.Normal);
                RigidTransform.Transform(ref hit.Location, ref transform, out hit.Location);
                return true;
//.........这里部分代码省略.........

        /// <summary>
        /// Casts a convex shape against the collidable.
        /// </summary>
        /// <param name="castShape">Shape to cast.</param>
        /// <param name="startingTransform">Initial transform of the shape.</param>
        /// <param name="sweep">Sweep to apply to the shape.</param>
        /// <param name="hit">Hit data, if any.</param>
        /// <returns>Whether or not the cast hit anything.</returns>
        public override bool ConvexCast(ConvexShape castShape, ref RigidTransform startingTransform, ref Vector3 sweep, out RayHit hit)
        {
            if (Shape.solidity == MobileMeshSolidity.Solid)
            {
                //If the convex cast is inside the mesh and the mesh is solid, it should return t = 0.
                var ray = new Ray() { Position = startingTransform.Position, Direction = Toolbox.UpVector };
                if (Shape.IsLocalRayOriginInMesh(ref ray, out hit))
                {

                    hit = new RayHit() { Location = startingTransform.Position, Normal = new Vector3(), T = 0 };
                    return true;
                }
            }
            hit = new RayHit();
            BoundingBox boundingBox;
            var transform = new AffineTransform {Translation = worldTransform.Position};
            Matrix3x3.CreateFromQuaternion(ref worldTransform.Orientation, out transform.LinearTransform);
            castShape.GetSweptLocalBoundingBox(ref startingTransform, ref transform, ref sweep, out boundingBox);
            var tri = PhysicsResources.GetTriangle();
            var hitElements = CommonResources.GetIntList();
            if (this.Shape.TriangleMesh.Tree.GetOverlaps(boundingBox, hitElements))
            {
                hit.T = float.MaxValue;
                for (int i = 0; i < hitElements.Count; i++)
                {
                    Shape.TriangleMesh.Data.GetTriangle(hitElements[i], out tri.vA, out tri.vB, out tri.vC);
                    AffineTransform.Transform(ref tri.vA, ref transform, out tri.vA);
                    AffineTransform.Transform(ref tri.vB, ref transform, out tri.vB);
                    AffineTransform.Transform(ref tri.vC, ref transform, out tri.vC);
                    Vector3 center;
                    Vector3.Add(ref tri.vA, ref tri.vB, out center);
                    Vector3.Add(ref center, ref tri.vC, out center);
                    Vector3.Multiply(ref center, 1f / 3f, out center);
                    Vector3.Subtract(ref tri.vA, ref center, out tri.vA);
                    Vector3.Subtract(ref tri.vB, ref center, out tri.vB);
                    Vector3.Subtract(ref tri.vC, ref center, out tri.vC);
                    tri.MaximumRadius = tri.vA.LengthSquared();
                    float radius = tri.vB.LengthSquared();
                    if (tri.MaximumRadius < radius)
                        tri.MaximumRadius = radius;
                    radius = tri.vC.LengthSquared();
                    if (tri.MaximumRadius < radius)
                        tri.MaximumRadius = radius;
                    tri.MaximumRadius = (float)Math.Sqrt(tri.MaximumRadius);
                    tri.collisionMargin = 0;
                    var triangleTransform = new RigidTransform {Orientation = Quaternion.Identity, Position = center};
                    RayHit tempHit;
                    if (MPRToolbox.Sweep(castShape, tri, ref sweep, ref Toolbox.ZeroVector, ref startingTransform, ref triangleTransform, out tempHit) && tempHit.T < hit.T)
                    {
                        hit = tempHit;
                    }
                }
                tri.MaximumRadius = 0;
                PhysicsResources.GiveBack(tri);
                CommonResources.GiveBack(hitElements);
                return hit.T != float.MaxValue;
            }
            PhysicsResources.GiveBack(tri);
            CommonResources.GiveBack(hitElements);
            return false;
        }

        /// <summary>
        /// Updates the collection of supporting contacts.
        /// </summary>
        public void UpdateSupports(ref System.Numerics.Vector3 movementDirection)
        {
            bool hadTraction = HasTraction;

            //Reset traction/support.
            HasTraction = false;
            HasSupport = false;

            System.Numerics.Vector3 downDirection = characterBody.orientationMatrix.Down;
            System.Numerics.Vector3 bodyPosition = characterBody.position;

            //Compute the character's radius, minus a little margin. We want the rays to originate safely within the character's body.
            //Assume vertical rotational invariance. Spheres, cylinders, and capsules don't have varying horizontal radii.
            System.Numerics.Vector3 extremePoint;
            var convexShape = characterBody.CollisionInformation.Shape as ConvexShape;
            Debug.Assert(convexShape != null, "Character bodies must be convex.");

            //Find the lowest point on the collision shape.
            convexShape.GetLocalExtremePointWithoutMargin(ref Toolbox.DownVector, out extremePoint);
            BottomDistance = -extremePoint.Y + convexShape.collisionMargin;

            convexShape.GetLocalExtremePointWithoutMargin(ref Toolbox.RightVector, out extremePoint);
            float rayCastInnerRadius = Math.Max((extremePoint.X + convexShape.collisionMargin) * 0.8f, extremePoint.X);

            //Vertically, the rays will start at the same height as the character's center.
            //While they could be started lower on a cylinder, that wouldn't always work for a sphere or capsule: the origin might end up outside of the shape!

            tractionContacts.Clear();
            supportContacts.Clear();
            sideContacts.Clear();
            headContacts.Clear();

            foreach (var pair in characterBody.CollisionInformation.Pairs)
            {
                //Don't stand on things that aren't really colliding fully.
                if (pair.CollisionRule != CollisionRule.Normal)
                    continue;
                ContactCategorizer.CategorizeContacts(pair, characterBody.CollisionInformation, ref downDirection, ref tractionContacts, ref supportContacts, ref sideContacts, ref headContacts);
            }

            HasSupport = supportContacts.Count > 0;
            HasTraction = tractionContacts.Count > 0;

            //Only perform ray casts if the character has fully left the surface, and only if the previous frame had traction.
            //(If ray casts are allowed when support contacts still exist, the door is opened for climbing surfaces which should not be climbable.
            //Consider a steep slope. If the character runs at it, the character will likely be wedged off of the ground, making it lose traction while still having a support contact with the slope.
            //If ray tests are allowed when support contacts exist, the character will maintain traction despite climbing the wall.
            //The VerticalMotionConstraint can stop the character from climbing in many cases, but it's nice not to have to rely on it.
            //Disallowing ray tests when supports exist does have a cost, though. For example, consider rounded steps.
            //If the character walks off a step such that it is still in contact with the step but is far enough down that the slope is too steep for traction,
            //the ray test won't recover traction. This situation just isn't very common.)
            if (!HasSupport && hadTraction)
            {
                float supportRayLength = maximumAssistedDownStepHeight + BottomDistance;
                SupportRayData = null;
                //If the contacts aren't available to support the character, raycast down to find the ground.
                if (!HasTraction)
                {
                    //TODO: could also require that the character has a nonzero movement direction in order to use a ray cast.  Questionable- would complicate the behavior on edges.
                    Ray ray = new Ray(bodyPosition, downDirection);

                    bool hasTraction;
                    SupportRayData data;
                    if (TryDownCast(ref ray, supportRayLength, out hasTraction, out data))
                    {
                        SupportRayData = data;
                        HasTraction = data.HasTraction;
                        HasSupport = true;
                    }
                }

                //If contacts and the center ray cast failed, try a ray offset in the movement direction.
                bool tryingToMove = movementDirection.LengthSquared() > 0;
                if (!HasTraction && tryingToMove)
                {
                    Ray ray = new Ray(
                        characterBody.Position +
                        movementDirection * rayCastInnerRadius, downDirection);

                    //Have to test to make sure the ray doesn't get obstructed.  This could happen if the character is deeply embedded in a wall; we wouldn't want it detecting things inside the wall as a support!
                    Ray obstructionRay;
                    obstructionRay.Position = characterBody.Position;
                    obstructionRay.Direction = ray.Position - obstructionRay.Position;
                    if (!QueryManager.RayCastHitAnything(obstructionRay, 1))
                    {
                        //The origin isn't obstructed, so now ray cast down.
                        bool hasTraction;
                        SupportRayData data;
                        if (TryDownCast(ref ray, supportRayLength, out hasTraction, out data))
                        {
                            if (SupportRayData == null || data.HitData.T < SupportRayData.Value.HitData.T)
                            {
                                //Only replace the previous support ray if we now have traction or we didn't have a support ray at all before,
                                //or this hit is a better (sooner) hit.
                                if (hasTraction)
                                {
                                    SupportRayData = data;
//.........这里部分代码省略.........

        //TODO: Consider changing the termination epsilons on these casts.  Epsilon * Modifier is okay, but there might be better options.

        ///<summary>
        /// Tests a ray against a convex shape.
        ///</summary>
        ///<param name="ray">Ray to test against the shape.</param>
        ///<param name="shape">Shape to test.</param>
        ///<param name="shapeTransform">Transform to apply to the shape for the test.</param>
        ///<param name="maximumLength">Maximum length of the ray in units of the ray direction's length.</param>
        ///<param name="hit">Hit data of the ray cast, if any.</param>
        ///<returns>Whether or not the ray hit the shape.</returns>
        public static bool RayCast(Ray ray, ConvexShape shape, ref RigidTransform shapeTransform, float maximumLength,
                                   out RayHit hit)
        {
            //Transform the ray into the object's local space.
            Vector3.Subtract(ref ray.Position, ref shapeTransform.Position, out ray.Position);
            Quaternion conjugate;
            Quaternion.Conjugate(ref shapeTransform.Orientation, out conjugate);
            Quaternion.Transform(ref ray.Position, ref conjugate, out ray.Position);
            Quaternion.Transform(ref ray.Direction, ref conjugate, out ray.Direction);

            Vector3 extremePointToRayOrigin, extremePoint;
            hit.T = 0;
            hit.Location = ray.Position;
            hit.Normal = Toolbox.ZeroVector;
            Vector3 closestOffset = hit.Location;

            RaySimplex simplex = new RaySimplex();

            float vw, closestPointDotDirection;
            int count = 0;
            //This epsilon has a significant impact on performance and accuracy.  Changing it to use BigEpsilon instead increases speed by around 30-40% usually, but jigging is more evident.
            while (closestOffset.LengthSquared() >= Toolbox.Epsilon * simplex.GetErrorTolerance(ref ray.Position))
            {
                if (++count > MaximumGJKIterations)
                {
                    //It's taken too long to find a hit.  Numerical problems are probable; quit.
                    hit = new RayHit();
                    return false;
                }

                shape.GetLocalExtremePoint(closestOffset, out extremePoint);

                Vector3.Subtract(ref hit.Location, ref extremePoint, out extremePointToRayOrigin);
                Vector3.Dot(ref closestOffset, ref extremePointToRayOrigin, out vw);
                //If the closest offset and the extreme point->ray origin direction point the same way,
                //then we might be able to conservatively advance the point towards the surface.
                if (vw > 0)
                {
                    
                    Vector3.Dot(ref closestOffset, ref ray.Direction, out closestPointDotDirection);
                    if (closestPointDotDirection >= 0)
                    {
                        hit = new RayHit();
                        return false;
                    }
                    hit.T = hit.T - vw / closestPointDotDirection;
                    if (hit.T > maximumLength)
                    {
                        //If we've gone beyond where the ray can reach, there's obviously no hit.
                        hit = new RayHit();
                        return false;
                    }
                    //Shift the ray up.
                    Vector3.Multiply(ref ray.Direction, hit.T, out hit.Location);
                    Vector3.Add(ref hit.Location, ref ray.Position, out hit.Location);
                    hit.Normal = closestOffset;
                }

                RaySimplex shiftedSimplex;
                simplex.AddNewSimplexPoint(ref extremePoint, ref hit.Location, out shiftedSimplex);

                //Compute the offset from the simplex surface to the origin.
                shiftedSimplex.GetPointClosestToOrigin(ref simplex, out closestOffset);

            }
            //Transform the hit data into world space.
            Quaternion.Transform(ref hit.Normal, ref shapeTransform.Orientation, out hit.Normal);
            Quaternion.Transform(ref hit.Location, ref shapeTransform.Orientation, out hit.Location);
            Vector3.Add(ref hit.Location, ref shapeTransform.Position, out hit.Location);

            return true;
        }