FSO.SimAntics.VMContext.GetObjPlace C# (CSharp) Method

        public VMPlacementResult GetObjPlace(VMEntity target, LotTilePos pos, Direction dir)
        {
            //ok, this might be confusing...
            short allowedHeights = target.GetValue(VMStackObjectVariable.AllowedHeightFlags);
            short weight = target.GetValue(VMStackObjectVariable.Weight);
            bool noFloor = (allowedHeights&1)==0;

            var flags = (VMEntityFlags)target.GetValue(VMStackObjectVariable.Flags);
            bool allowAvatars = ((flags & VMEntityFlags.DisallowPersonIntersection) == 0) && ((flags & VMEntityFlags.AllowPersonIntersection) > 0);

            VMObstacle footprint = target.GetObstacle(pos, dir);
            ushort room = GetRoomAt(pos);

            VMPlacementError status = (noFloor)?VMPlacementError.HeightNotAllowed:VMPlacementError.Success;
            VMEntity statusObj = null;

            if (footprint == null || pos.Level < 1)
            {
                return new VMPlacementResult { Status = status };
            }

            var objs = RoomInfo[room].Entities;
            foreach (var obj in objs)
            {
                if (obj.MultitileGroup == target.MultitileGroup || (obj is VMAvatar && allowAvatars)
                    || (target.GhostImage && target.GhostOriginal != null && target.GhostOriginal.Objects.Contains(obj))) continue;
                var oFoot = obj.Footprint;

                if (oFoot != null && oFoot.Intersects(footprint)
                    && (!(target.ExecuteEntryPoint(5, this, true, obj, new short[] { obj.ObjectID, 0, 0, 0 })
                        || obj.ExecuteEntryPoint(5, this, true, target, new short[] { target.ObjectID, 0, 0, 0 })))
                    )
                {
                    statusObj = obj;
                    status = VMPlacementError.CantIntersectOtherObjects;

                    //this object is technically solid. Check if we can place on top of it
                    if (allowedHeights>1 && obj.TotalSlots() > 0 && (obj.GetSlot(0) == null || obj.GetSlot(0) == target))
                    {
                        //first check if we have a slot 0, which is what we place onto. then check if it's empty,
                        //then check if the object can support this one's weight.
                        //we also need to make sure that the height of this specific slot is allowed.

                        if (((1 << (obj.GetSlotHeight(0) - 1)) & allowedHeights) > 0)
                        {
                            if (weight < obj.GetValue(VMStackObjectVariable.SupportStrength))
                            {
                                return new VMPlacementResult(VMPlacementError.Success, obj);
                            }
                            else
                            {
                                status = VMPlacementError.CantSupportWeight;
                            }
                        }
                        else
                        {
                            if (noFloor)
                            {
                                if ((allowedHeights & (1 << 3)) > 0) status = VMPlacementError.CounterHeight;
                                else status = (obj.GetSlotHeight(0) == 8) ? VMPlacementError.CannotPlaceComputerOnEndTable : VMPlacementError.HeightNotAllowed;
                            }
                        }
                    }
                }

            }
            return new VMPlacementResult(status, statusObj);
        }

        public VMPlacementResult PositionValid(LotTilePos pos,Direction direction,VMContext context)
        {
            if (pos == LotTilePos.OUT_OF_WORLD)
            {
                return(new VMPlacementResult());
            }
            else if (context.IsOutOfBounds(pos))
            {
                return new VMPlacementResult {
                           Status = VMPlacementError.LocationOutOfBounds
                }
            }
            ;

            //TODO: speedup with exit early checks
            //TODO: corner checks (wtf uses this)

            var arch = context.Architecture;
            var wall = arch.GetWall(pos.TileX,pos.TileY,pos.Level); //todo: preprocess to check which walls are real solid walls and not fences.

            if (this is VMGameObject)                               //needs special handling for avatar eventually
            {
                VMPlacementError wallValid = WallChangeValid(wall,direction,true);

                if (wallValid != VMPlacementError.Success)
                {
                    return new VMPlacementResult {
                               Status = wallValid
                    }
                }
                ;
            }

            var floor = arch.GetFloor(pos.TileX,pos.TileY,pos.Level);
            VMPlacementError floorValid = FloorChangeValid(floor,pos.Level);

            if (floorValid != VMPlacementError.Success)
            {
                return new VMPlacementResult {
                           Status = floorValid
                }
            }
            ;

            //we've passed the wall test, now check if we intersect any objects.
            var valid = (this is VMAvatar)? context.GetAvatarPlace(this,pos,direction) : context.GetObjPlace(this,pos,direction);

            return(valid);
        }