getDerivedCP() public method

public getDerivedCP ( ) : Vector3
return Vector3
Esempio n. 1
0
        // check if portal is close to another portal.
        // Note, both portals are assumed to be stationary
        // and DerivedCP is the current position.
        // this function is INTENTIONALLY NOT EXACT because
        // it is used by PCZSM::connectPortalsToTargetZonesByLocation
        // which is a utility function to link up nearby portals
        //
        public bool closeTo(Portal otherPortal)
        {
            // only portals of the same type can be "close to" each other.
            if (this.mType != otherPortal.Type)
            {
                return(false);
            }
            bool close = false;

            switch (this.mType)
            {
            default:
            case PORTAL_TYPE.PORTAL_TYPE_QUAD:
            {
                // quad portals must be within 1/4 sphere of each other
                Sphere quarterSphere1 = this.mDerivedSphere;
                quarterSphere1.Radius = quarterSphere1.Radius * 0.25f;
                Sphere quarterSphere2 = otherPortal.getDerivedSphere();
                quarterSphere2.Radius = quarterSphere2.Radius * 0.25f;
                close = quarterSphere1.Intersects(quarterSphere2);
            }
            break;

            case PORTAL_TYPE.PORTAL_TYPE_AABB:
                // NOTE: AABB's must match perfectly
                if (this.mDerivedCP == otherPortal.getDerivedCP() && this.mCorners[0] == otherPortal.getCorner(0) &&
                    this.mCorners[1] == otherPortal.getCorner(1))
                {
                    close = true;
                }
                break;

            case PORTAL_TYPE.PORTAL_TYPE_SPHERE:
                // NOTE: Spheres must match perfectly
                if (this.mDerivedCP == otherPortal.getDerivedCP() && this.mRadius == otherPortal.getRadius())
                {
                    close = true;
                }
                break;
            }
            return(close);
        }
Esempio n. 2
0
		/// <summary>
		///     IsObjectVisible() function for portals.
		/// </summary>
		/// <remarks>
		///     Everything needs to be updated spatially before this function is
		///     called including portal corners, frustum planes, etc.
		/// </remarks>
		/// <param name="portal">
		///     The <see cref="Portal"/> to check visibility against.
		/// </param>
		/// <param name="culledBy">
		///     The <see cref="FrustumPlane"/> that the Portal is in.
		/// </param>
		/// <returns>
		///     true if the Portal is visible.
		/// </returns>
		public bool IsObjectVisible( Portal portal, out FrustumPlane culledBy )
		{
			culledBy = FrustumPlane.None;

			// if portal isn't open, it's not visible
			if ( !portal.IsOpen )
			{
				return false;
			}

			// check the extra frustum first
			if ( !this.extraCullingFrustum.IsObjectVisible( portal ) )
			{
				return false;
			}

			// if portal is of type AABB or Sphere, then use simple bound check against planes
			if ( portal.Type == PORTAL_TYPE.PORTAL_TYPE_AABB )
			{
				var aabb = new AxisAlignedBox( portal.getDerivedCorner( 0 ), portal.getDerivedCorner( 1 ) );
				return base.IsObjectVisible( aabb, out culledBy );
			}
			else if ( portal.Type == PORTAL_TYPE.PORTAL_TYPE_SPHERE )
			{
				return base.IsObjectVisible( portal.getDerivedSphere(), out culledBy );
			}

			// check if the portal norm is facing the camera
			Vector3 cameraToPortal = portal.getDerivedCP() - DerivedPosition;
			Vector3 portalDirection = portal.getDerivedDirection();
			Real dotProduct = cameraToPortal.Dot( portalDirection );
			if ( dotProduct > 0 )
			{
				// portal is faced away from camera
				return false;
			}
			// check against regular frustum planes
			bool visible_flag;
			if ( null != CullFrustum )
			{
				// For each frustum plane, see if all points are on the negative side
				// If so, object is not visible
				// NOTE: We skip the NEAR plane (plane #0) because Portals need to
				// be visible no matter how close you get to them.

				for ( int plane = 1; plane < 6; ++plane )
				{
					// set the visible flag to false
					visible_flag = false;
					// Skip far plane if infinite view frustum
					if ( (FrustumPlane)plane == FrustumPlane.Far && _farDistance == 0 )
					{
						continue;
					}

					// we have to check each corner of the portal
					for ( int corner = 0; corner < 4; corner++ )
					{
						PlaneSide side = CullFrustum.FrustumPlanes[ plane ].GetSide( portal.getDerivedCorner( corner ) );
						if ( side != PlaneSide.Negative )
						{
							visible_flag = true;
						}
					}
					// if the visible_flag is still false, then this plane
					// culled all the portal points
					if ( visible_flag == false )
					{
						// ALL corners on negative side therefore out of view
						if ( culledBy != FrustumPlane.None )
						{
							culledBy = (FrustumPlane)plane;
						}
						return false;
					}
				}
			}
			else
			{
				// Make any pending updates to the calculated frustum planes
				UpdateFrustumPlanes();

				// For each frustum plane, see if all points are on the negative side
				// If so, object is not visible
				// NOTE: We skip the NEAR plane (plane #0) because Portals need to
				// be visible no matter how close you get to them.
				// BUGBUG: This can cause a false positive situation when a portal is
				// behind the camera but close.  This could be fixed by having another
				// culling plane at the camera location with normal same as camera direction.
				for ( int plane = 1; plane < 6; ++plane )
				{
					// set the visible flag to false
					visible_flag = false;
					// Skip far plane if infinite view frustum
					if ( (FrustumPlane)plane == FrustumPlane.Far && _farDistance == 0 )
					{
						continue;
					}

					// we have to check each corner of the portal
					for ( int corner = 0; corner < 4; corner++ )
					{
						PlaneSide side = _planes[ plane ].GetSide( portal.getDerivedCorner( corner ) );
						if ( side != PlaneSide.Negative )
						{
							visible_flag = true;
						}
					}
					// if the visible_flag is still false, then this plane
					// culled all the portal points
					if ( visible_flag == false )
					{
						// ALL corners on negative side therefore out of view
						if ( culledBy != FrustumPlane.None )
						{
							culledBy = (FrustumPlane)plane;
						}
						return false;
					}
				}
			}
			// no plane culled all the portal points and the norm
			// was facing the camera, so this portal is visible
			return true;
		}
Esempio n. 3
0
		/// <summary>
		///     IsObjectVisible() function for portals.
		/// </summary>
		/// <remarks>
		///     Everything needs to be updated spatially before this function is
		///     called including portal corners, frustum planes, etc.
		/// </remarks>
		/// <param name="portal">
		///     The <see cref="Portal"/> to check visibility against.
		/// </param>
		/// <returns>
		///     true if the Portal is visible.
		/// </returns>
		public bool IsObjectVisible( Portal portal )
		{
			// if portal isn't open, it's not visible
			if ( !portal.IsOpen )
			{
				return false;
			}

			// if the frustum has no planes, just return true
			if ( mActiveCullingPlanes.Count == 0 )
			{
				return true;
			}
			// check if this portal is already in the list of active culling planes (avoid
			// infinite recursion case)
			foreach ( PCPlane plane in mActiveCullingPlanes )
			{
				if ( plane.Portal == portal )
				{
					return false;
				}
			}

			// if portal is of type AABB or Sphere, then use simple bound check against planes
			if ( portal.Type == PORTAL_TYPE.PORTAL_TYPE_AABB )
			{
				AxisAlignedBox aabb = new AxisAlignedBox();
				aabb.SetExtents( portal.getDerivedCorner( 0 ), portal.getDerivedCorner( 1 ) );
				return IsObjectVisible( aabb );
			}
			else if ( portal.Type == PORTAL_TYPE.PORTAL_TYPE_SPHERE )
			{
				return IsObjectVisible( portal.getDerivedSphere() );
			}

			// check if the portal norm is facing the frustum
			Vector3 frustumToPortal = portal.getDerivedCP() - mOrigin;
			Vector3 portalDirection = portal.getDerivedDirection();
			Real dotProduct = frustumToPortal.Dot( portalDirection );
			if ( dotProduct > 0 )
			{
				// portal is faced away from Frustum
				return false;
			}

			// check against frustum culling planes
			bool visible_flag;

			// Check originPlane if told to
			if ( mUseOriginPlane )
			{
				// set the visible flag to false
				visible_flag = false;
				// we have to check each corner of the portal
				for ( int corner = 0; corner < 4; corner++ )
				{
					PlaneSide side = mOriginPlane.GetSide( portal.getDerivedCorner( corner ) );
					if ( side != PlaneSide.Negative )
					{
						visible_flag = true;
					}
				}
				// if the visible_flag is still false, then the origin plane
				// culled all the portal points
				if ( visible_flag == false )
				{
					// ALL corners on negative side therefore out of view
					return false;
				}
			}

			// For each active culling plane, see if all portal points are on the negative
			// side. If so, the portal is not visible
			foreach ( PCPlane plane in mActiveCullingPlanes )
			{
				visible_flag = false;
				// we have to check each corner of the portal
				for ( int corner = 0; corner < 4; corner++ )
				{
					PlaneSide side = plane.GetSide( portal.getDerivedCorner( corner ) );
					if ( side != PlaneSide.Negative )
					{
						visible_flag = true;
					}
				}
				// if the visible_flag is still false, then this plane
				// culled all the portal points
				if ( visible_flag == false )
				{
					// ALL corners on negative side therefore out of view
					return false;
				}

			}

			// no plane culled all the portal points and the norm
			// was facing the frustum, so this portal is visible
			return true;
		}
Esempio n. 4
0
        /// <summary>
        ///     IsObjectVisible() function for portals.
        /// </summary>
        /// <remarks>
        ///     Everything needs to be updated spatially before this function is
        ///     called including portal corners, frustum planes, etc.
        /// </remarks>
        /// <param name="portal">
        ///     The <see cref="Portal"/> to check visibility against.
        /// </param>
        /// <returns>
        ///     true if the Portal is visible.
        /// </returns>
        public bool IsObjectVisible(Portal portal)
        {
            // if portal isn't open, it's not visible
            if (!portal.IsOpen)
            {
                return(false);
            }

            // if the frustum has no planes, just return true
            if (this.mActiveCullingPlanes.Count == 0)
            {
                return(true);
            }
            // check if this portal is already in the list of active culling planes (avoid
            // infinite recursion case)
            foreach (PCPlane plane in this.mActiveCullingPlanes)
            {
                if (plane.Portal == portal)
                {
                    return(false);
                }
            }

            // if portal is of type AABB or Sphere, then use simple bound check against planes
            if (portal.Type == PORTAL_TYPE.PORTAL_TYPE_AABB)
            {
                var aabb = new AxisAlignedBox();
                aabb.SetExtents(portal.getDerivedCorner(0), portal.getDerivedCorner(1));
                return(IsObjectVisible(aabb));
            }
            else if (portal.Type == PORTAL_TYPE.PORTAL_TYPE_SPHERE)
            {
                return(IsObjectVisible(portal.getDerivedSphere()));
            }

            // check if the portal norm is facing the frustum
            Vector3 frustumToPortal = portal.getDerivedCP() - this.mOrigin;
            Vector3 portalDirection = portal.getDerivedDirection();
            Real    dotProduct      = frustumToPortal.Dot(portalDirection);

            if (dotProduct > 0)
            {
                // portal is faced away from Frustum
                return(false);
            }

            // check against frustum culling planes
            bool visible_flag;

            // Check originPlane if told to
            if (this.mUseOriginPlane)
            {
                // set the visible flag to false
                visible_flag = false;
                // we have to check each corner of the portal
                for (int corner = 0; corner < 4; corner++)
                {
                    PlaneSide side = this.mOriginPlane.GetSide(portal.getDerivedCorner(corner));
                    if (side != PlaneSide.Negative)
                    {
                        visible_flag = true;
                    }
                }
                // if the visible_flag is still false, then the origin plane
                // culled all the portal points
                if (visible_flag == false)
                {
                    // ALL corners on negative side therefore out of view
                    return(false);
                }
            }

            // For each active culling plane, see if all portal points are on the negative
            // side. If so, the portal is not visible
            foreach (PCPlane plane in this.mActiveCullingPlanes)
            {
                visible_flag = false;
                // we have to check each corner of the portal
                for (int corner = 0; corner < 4; corner++)
                {
                    PlaneSide side = plane.GetSide(portal.getDerivedCorner(corner));
                    if (side != PlaneSide.Negative)
                    {
                        visible_flag = true;
                    }
                }
                // if the visible_flag is still false, then this plane
                // culled all the portal points
                if (visible_flag == false)
                {
                    // ALL corners on negative side therefore out of view
                    return(false);
                }
            }

            // no plane culled all the portal points and the norm
            // was facing the frustum, so this portal is visible
            return(true);
        }
Esempio n. 5
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        /* This function check if *this* portal "crossed over" the other portal.
         */

        public bool crossedPortal(Portal otherPortal)
        {
            // Only check if portal is open
            if (otherPortal.mOpen)
            {
                // we model both portals as line swept spheres (mPrevDerivedCP to mDerivedCP).
                // intersection test is then between the capsules.
                // BUGBUG! This routine needs to check for case where one or both objects
                //         don't move - resulting in simple sphere tests
                // BUGBUG! If one (or both) portals are aabb's this is REALLY not accurate.
                Capsule portalCapsule, otherPortalCapsule;

                portalCapsule = new Capsule();
                portalCapsule.Set(getPrevDerivedCP(), getDerivedCP(), getRadius());

                otherPortalCapsule = new Capsule();
                otherPortalCapsule.Set(otherPortal.mPrevDerivedCP, otherPortal.mDerivedCP, otherPortal.mRadius);

                if (portalCapsule.Intersects(otherPortalCapsule))
                {
                    // the portal intersected the other portal at some time from last frame to this frame.
                    // Now check if this portal "crossed" the other portal
                    switch (otherPortal.Type)
                    {
                    case PORTAL_TYPE.PORTAL_TYPE_QUAD:
                        // a crossing occurs if the "side" of the final position of this portal compared
                        // to the final position of the other portal is negative AND the initial position
                        // of this portal compared to the initial position of the other portal is non-negative
                        // NOTE: This function assumes that this portal is the smaller portal potentially crossing
                        //       over the otherPortal which is larger.
                        if (otherPortal.getDerivedPlane().GetSide(this.mDerivedCP) == PlaneSide.Negative &&
                            otherPortal.getPrevDerivedPlane().GetSide(this.mPrevDerivedCP) != PlaneSide.Negative)
                        {
                            // crossing occurred!
                            return(true);
                        }
                        break;

                    case PORTAL_TYPE.PORTAL_TYPE_AABB:
                    {
                        // for aabb's we check if the center point went from being inside to being outside
                        // the aabb (or vice versa) for crossing.
                        var aabb = new AxisAlignedBox(otherPortal.getDerivedCorner(0), otherPortal.getDerivedCorner(1));
                        //bool previousInside = aabb.contains(mPrevDerivedCP);
                        bool currentInside = aabb.Contains(this.mDerivedCP);
                        if (otherPortal.getDerivedDirection() == Vector3.UnitZ)
                        {
                            // portal norm is "outward" pointing, look for going from outside to inside
                            //if (previousInside == false &&
                            if (currentInside == true)
                            {
                                return(true);
                            }
                        }
                        else
                        {
                            // portal norm is "inward" pointing, look for going from inside to outside
                            //if (previousInside == true &&
                            if (currentInside == false)
                            {
                                return(true);
                            }
                        }
                    }
                    break;

                    case PORTAL_TYPE.PORTAL_TYPE_SPHERE:
                    {
                        // for spheres we check if the center point went from being inside to being outside
                        // the sphere surface (or vice versa) for crossing.
                        //Real previousDistance2 = mPrevDerivedCP.squaredDistance(otherPortal->getPrevDerivedCP());
                        Real currentDistance2 = this.mDerivedCP.DistanceSquared(otherPortal.getDerivedCP());
                        Real mRadius2         = System.Math.Sqrt(otherPortal.getRadius());
                        if (otherPortal.getDerivedDirection() == Vector3.UnitZ)
                        {
                            // portal norm is "outward" pointing, look for going from outside to inside
                            //if (previousDistance2 >= mRadius2 &&
                            if (currentDistance2 < mRadius2)
                            {
                                return(true);
                            }
                        }
                        else
                        {
                            // portal norm is "inward" pointing, look for going from inside to outside
                            //if (previousDistance2 < mRadius2 &&
                            if (currentDistance2 >= mRadius2)
                            {
                                return(true);
                            }
                        }
                    }
                    break;
                    }
                }
            }
            // there was no crossing of the portal by this portal. It might be touching
            // the other portal (but we don't care currently)
            return(false);
        }
Esempio n. 6
0
		/* This function check if *this* portal "crossed over" the other portal.
		*/
		public bool crossedPortal( Portal otherPortal )
		{
			// Only check if portal is open
			if ( otherPortal.mOpen )
			{
				// we model both portals as line swept spheres (mPrevDerivedCP to mDerivedCP).
				// intersection test is then between the capsules.
				// BUGBUG! This routine needs to check for case where one or both objects
				//         don't move - resulting in simple sphere tests
				// BUGBUG! If one (or both) portals are aabb's this is REALLY not accurate.
				Capsule portalCapsule, otherPortalCapsule;

				portalCapsule = new Capsule();
				portalCapsule.Set( this.getPrevDerivedCP(), this.getDerivedCP(), this.getRadius() );

				otherPortalCapsule = new Capsule();
				otherPortalCapsule.Set( otherPortal.mPrevDerivedCP,
									   otherPortal.mDerivedCP,
									   otherPortal.mRadius );

				if ( portalCapsule.Intersects( otherPortalCapsule ) )
				{
					// the portal intersected the other portal at some time from last frame to this frame.
					// Now check if this portal "crossed" the other portal
					switch ( otherPortal.Type )
					{
						case PORTAL_TYPE.PORTAL_TYPE_QUAD:
							// a crossing occurs if the "side" of the final position of this portal compared
							// to the final position of the other portal is negative AND the initial position
							// of this portal compared to the initial position of the other portal is non-negative
							// NOTE: This function assumes that this portal is the smaller portal potentially crossing
							//       over the otherPortal which is larger.
							if ( otherPortal.getDerivedPlane().GetSide( mDerivedCP ) == PlaneSide.Negative &&
								otherPortal.getPrevDerivedPlane().GetSide( mPrevDerivedCP ) != PlaneSide.Negative )
							{
								// crossing occurred!
								return true;
							}
							break;
						case PORTAL_TYPE.PORTAL_TYPE_AABB:
							{
								// for aabb's we check if the center point went from being inside to being outside
								// the aabb (or vice versa) for crossing.
								AxisAlignedBox aabb = new AxisAlignedBox( otherPortal.getDerivedCorner( 0 ), otherPortal.getDerivedCorner( 1 ) );
								//bool previousInside = aabb.contains(mPrevDerivedCP);
								bool currentInside = aabb.Contains( mDerivedCP );
								if ( otherPortal.getDerivedDirection() == Vector3.UnitZ )
								{
									// portal norm is "outward" pointing, look for going from outside to inside
									//if (previousInside == false &&
									if ( currentInside == true )
									{
										return true;
									}
								}
								else
								{
									// portal norm is "inward" pointing, look for going from inside to outside
									//if (previousInside == true &&
									if ( currentInside == false )
									{
										return true;
									}
								}
							}
							break;
						case PORTAL_TYPE.PORTAL_TYPE_SPHERE:
							{
								// for spheres we check if the center point went from being inside to being outside
								// the sphere surface (or vice versa) for crossing.
								//Real previousDistance2 = mPrevDerivedCP.squaredDistance(otherPortal->getPrevDerivedCP());
								Real currentDistance2 = mDerivedCP.DistanceSquared( otherPortal.getDerivedCP() );
								Real mRadius2 = System.Math.Sqrt( otherPortal.getRadius() );
								if ( otherPortal.getDerivedDirection() == Vector3.UnitZ )
								{
									// portal norm is "outward" pointing, look for going from outside to inside
									//if (previousDistance2 >= mRadius2 &&
									if ( currentDistance2 < mRadius2 )
									{
										return true;
									}
								}
								else
								{
									// portal norm is "inward" pointing, look for going from inside to outside
									//if (previousDistance2 < mRadius2 &&
									if ( currentDistance2 >= mRadius2 )
									{
										return true;
									}
								}
							}
							break;
					}
				}
			}
			// there was no crossing of the portal by this portal. It might be touching
			// the other portal (but we don't care currently)
			return false;
		}
Esempio n. 7
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		// check if portal is close to another portal.
		// Note, both portals are assumed to be stationary
		// and DerivedCP is the current position.
		// this function is INTENTIONALLY NOT EXACT because
		// it is used by PCZSM::connectPortalsToTargetZonesByLocation
		// which is a utility function to link up nearby portals
		//
		public bool closeTo( Portal otherPortal )
		{
			// only portals of the same type can be "close to" each other.
			if ( mType != otherPortal.Type )
			{
				return false;
			}
			bool close = false;
			switch ( mType )
			{
				default:
				case PORTAL_TYPE.PORTAL_TYPE_QUAD:
					{
						// quad portals must be within 1/4 sphere of each other
						Sphere quarterSphere1 = mDerivedSphere;
						quarterSphere1.Radius = quarterSphere1.Radius * 0.25f;
						Sphere quarterSphere2 = otherPortal.getDerivedSphere();
						quarterSphere2.Radius = quarterSphere2.Radius * 0.25f;
						close = quarterSphere1.Intersects( quarterSphere2 );
					}
					break;
				case PORTAL_TYPE.PORTAL_TYPE_AABB:
					// NOTE: AABB's must match perfectly
					if ( mDerivedCP == otherPortal.getDerivedCP() &&
						mCorners[ 0 ] == otherPortal.getCorner( 0 ) &&
						mCorners[ 1 ] == otherPortal.getCorner( 1 ) )
					{
						close = true;
					}
					break;
				case PORTAL_TYPE.PORTAL_TYPE_SPHERE:
					// NOTE: Spheres must match perfectly
					if ( mDerivedCP == otherPortal.getDerivedCP() &&
						mRadius == otherPortal.getRadius() )
					{
						close = true;
					}
					break;
			}
			return close;
		}
Esempio n. 8
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        /// <summary>
        ///     IsObjectVisible() function for portals.
        /// </summary>
        /// <remarks>
        ///     Everything needs to be updated spatially before this function is
        ///     called including portal corners, frustum planes, etc.
        /// </remarks>
        /// <param name="portal">
        ///     The <see cref="Portal"/> to check visibility against.
        /// </param>
        /// <param name="culledBy">
        ///     The <see cref="FrustumPlane"/> that the Portal is in.
        /// </param>
        /// <returns>
        ///     true if the Portal is visible.
        /// </returns>
        public bool IsObjectVisible(Portal portal, out FrustumPlane culledBy)
        {
            culledBy = FrustumPlane.None;

            // if portal isn't open, it's not visible
            if (!portal.IsOpen)
            {
                return(false);
            }

            // check the extra frustum first
            if (!this.extraCullingFrustum.IsObjectVisible(portal))
            {
                return(false);
            }

            // if portal is of type AABB or Sphere, then use simple bound check against planes
            if (portal.Type == PORTAL_TYPE.PORTAL_TYPE_AABB)
            {
                var aabb = new AxisAlignedBox(portal.getDerivedCorner(0), portal.getDerivedCorner(1));
                return(base.IsObjectVisible(aabb, out culledBy));
            }
            else if (portal.Type == PORTAL_TYPE.PORTAL_TYPE_SPHERE)
            {
                return(base.IsObjectVisible(portal.getDerivedSphere(), out culledBy));
            }

            // check if the portal norm is facing the camera
            Vector3 cameraToPortal  = portal.getDerivedCP() - DerivedPosition;
            Vector3 portalDirection = portal.getDerivedDirection();
            Real    dotProduct      = cameraToPortal.Dot(portalDirection);

            if (dotProduct > 0)
            {
                // portal is faced away from camera
                return(false);
            }
            // check against regular frustum planes
            bool visible_flag;

            if (null != CullFrustum)
            {
                // For each frustum plane, see if all points are on the negative side
                // If so, object is not visible
                // NOTE: We skip the NEAR plane (plane #0) because Portals need to
                // be visible no matter how close you get to them.

                for (int plane = 1; plane < 6; ++plane)
                {
                    // set the visible flag to false
                    visible_flag = false;
                    // Skip far plane if infinite view frustum
                    if ((FrustumPlane)plane == FrustumPlane.Far && _farDistance == 0)
                    {
                        continue;
                    }

                    // we have to check each corner of the portal
                    for (int corner = 0; corner < 4; corner++)
                    {
                        PlaneSide side = CullFrustum.FrustumPlanes[plane].GetSide(portal.getDerivedCorner(corner));
                        if (side != PlaneSide.Negative)
                        {
                            visible_flag = true;
                        }
                    }
                    // if the visible_flag is still false, then this plane
                    // culled all the portal points
                    if (visible_flag == false)
                    {
                        // ALL corners on negative side therefore out of view
                        if (culledBy != FrustumPlane.None)
                        {
                            culledBy = (FrustumPlane)plane;
                        }
                        return(false);
                    }
                }
            }
            else
            {
                // Make any pending updates to the calculated frustum planes
                UpdateFrustumPlanes();

                // For each frustum plane, see if all points are on the negative side
                // If so, object is not visible
                // NOTE: We skip the NEAR plane (plane #0) because Portals need to
                // be visible no matter how close you get to them.
                // BUGBUG: This can cause a false positive situation when a portal is
                // behind the camera but close.  This could be fixed by having another
                // culling plane at the camera location with normal same as camera direction.
                for (int plane = 1; plane < 6; ++plane)
                {
                    // set the visible flag to false
                    visible_flag = false;
                    // Skip far plane if infinite view frustum
                    if ((FrustumPlane)plane == FrustumPlane.Far && _farDistance == 0)
                    {
                        continue;
                    }

                    // we have to check each corner of the portal
                    for (int corner = 0; corner < 4; corner++)
                    {
                        PlaneSide side = _planes[plane].GetSide(portal.getDerivedCorner(corner));
                        if (side != PlaneSide.Negative)
                        {
                            visible_flag = true;
                        }
                    }
                    // if the visible_flag is still false, then this plane
                    // culled all the portal points
                    if (visible_flag == false)
                    {
                        // ALL corners on negative side therefore out of view
                        if (culledBy != FrustumPlane.None)
                        {
                            culledBy = (FrustumPlane)plane;
                        }
                        return(false);
                    }
                }
            }
            // no plane culled all the portal points and the norm
            // was facing the camera, so this portal is visible
            return(true);
        }