TombEngine/TR5Main/Objects/TR5/Object/tr5_pushableblock.cpp

#include "framework.h"
#include "tr5_pushableblock.h"
#include "lara.h"
#include "draw.h"
#include "items.h"
#include "collide.h"
#include "effect.h"
#include "box.h"
#include "level.h"
#include "input.h"
#include "sound.h"
#define GET_PUSHABLEINFO(item) ((PUSHABLE_INFO*) item->data)

OBJECT_COLLISION_BOUNDS PushableBlockBounds = {
	0x0000, 0x0000, 0xFF00, 0x0000,
	0x0000, 0x0000, 0xF8E4, 0x071C,
	0xEAAC, 0x1554, 0xF8E4, 0x071C
};

PHD_VECTOR PushableBlockPos = { 0, 0, 0 };
int DoPushPull = 0;

void ClearMovableBlockSplitters(int x, int y, int z, short roomNumber)
{
	FLOOR_INFO* floor = GetFloor(x, y, z, &roomNumber);
	g_Level.Boxes[floor->box].flags &= (~BLOCKED);
	short height = g_Level.Boxes[floor->box].height;
	short baseRoomNumber = roomNumber;
	
	floor = GetFloor(x + 1024, y, z, &roomNumber);
	if (floor->box != NO_BOX)
	{
		if (g_Level.Boxes[floor->box].height == height && (g_Level.Boxes[floor->box].flags & BLOCKABLE) && (g_Level.Boxes[floor->box].flags & BLOCKED))
			ClearMovableBlockSplitters(x + 1024, y, z, roomNumber);
	}

	roomNumber = baseRoomNumber;
	floor = GetFloor(x - 1024, y, z, &roomNumber);
	if (floor->box != NO_BOX)
	{
		if (g_Level.Boxes[floor->box].height == height && (g_Level.Boxes[floor->box].flags & BLOCKABLE) && (g_Level.Boxes[floor->box].flags & BLOCKED))
			ClearMovableBlockSplitters(x - 1024, y, z, roomNumber);
	}

	roomNumber = baseRoomNumber;
	floor = GetFloor(x, y, z + 1024, &roomNumber);
	if (floor->box != NO_BOX)
	{
		if (g_Level.Boxes[floor->box].height == height && (g_Level.Boxes[floor->box].flags & BLOCKABLE) && (g_Level.Boxes[floor->box].flags & BLOCKED))
			ClearMovableBlockSplitters(x, y, z + 1024, roomNumber);
	}

	roomNumber = baseRoomNumber;
	floor = GetFloor(x, y, z - 1024, &roomNumber);
	if (floor->box != NO_BOX)
	{
		if (g_Level.Boxes[floor->box].height == height && (g_Level.Boxes[floor->box].flags & BLOCKABLE) && (g_Level.Boxes[floor->box].flags & BLOCKED))
			ClearMovableBlockSplitters(x, y, z - 1024, roomNumber);
	}
}

void InitialisePushableBlock(short itemNum)
{
	ITEM_INFO* item = &g_Level.Items[itemNum];
	item->itemFlags[1] = NO_ITEM; // need to use itemFlags[1] to hold linked index for now

	ClearMovableBlockSplitters(item->pos.xPos, item->pos.yPos, item->pos.zPos, item->roomNumber);
	
	// allocate new pushable info
	PUSHABLE_INFO* pushable = new PUSHABLE_INFO;
	
	pushable->stackLimit = 3; // LUA
	pushable->gravity = 9; // LUA
	pushable->weight = 100; // LUA
	pushable->moveX = item->pos.xPos;
	pushable->moveZ = item->pos.zPos;

	// read flags from OCB
	int OCB = item->triggerFlags;

	pushable->canFall = OCB & 0x20;
	pushable->hasFloorCeiling = OCB & 0x40;
	pushable->disablePull = OCB & 0x80;
	pushable->disablePush = OCB & 0x100;
	pushable->disableW = pushable->disableE = OCB & 0x200;
	pushable->disableN = pushable->disableS = OCB & 0x400;
	
	pushable->climb = 0; // maybe there will be better way to handle this than OCBs?
	/*
	pushable->climb |= (OCB & 0x800) ? CLIMB_WEST : 0;
	pushable->climb |= (OCB & 0x1000) ? CLIMB_NORTH : 0;
	pushable->climb |= (OCB & 0x2000) ? CLIMB_EAST : 0;
	pushable->climb |= (OCB & 0x4000) ? CLIMB_SOUTH : 0;
	*/

	int height;
	if (pushable->hasFloorCeiling)
	{
		height = (OCB & 0x1F) * CLICK(1);
		T5M::Floordata::AddBridge(itemNum);
	}
	else
		height = -GetBoundsAccurate(item)->Y1;

	pushable->height = height;

	pushable->loopSound = SFX_PUSHABLE_SOUND; // LUA
	pushable->stopSound = SFX_PUSH_BLOCK_END; // LUA
	pushable->fallSound = SFX_TR4_BOULDER_FALL; // LUA

	item->data = (void*) pushable;

	FindStack(itemNum); // check for stack formation on init
}

void PushableBlockControl(short itemNumber)
{
	ITEM_INFO* item = &g_Level.Items[itemNumber];
	Lara.generalPtr = (void*)itemNumber;

	PHD_VECTOR pos;
	pos.x = 0;
	pos.y = 0;
	pos.z = 0;

	short quadrant = (unsigned short)(LaraItem->pos.yRot + ANGLE(45)) / ANGLE(90);

	int x, z;
	short roomNumber;
	FLOOR_INFO* floor;
	ROOM_INFO* r;
	PUSHABLE_INFO* pushable = GET_PUSHABLEINFO(item);
	int blockHeight = GetStackHeight(item);

	// do sound effects, it works for now
	if (DoPushPull > 0)
	{
		SoundEffect(pushable->loopSound, &item->pos, 2);
	}
	else if (DoPushPull < 0)
	{
		DoPushPull = 0;
		SoundEffect(pushable->stopSound, &item->pos, 2);
	}

	// control block falling
	if (item->gravityStatus)
	{
		roomNumber = item->roomNumber;
		floor = GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &roomNumber);
		int floorHeight = GetFloorHeight(floor, item->pos.xPos, item->pos.yPos + 10, item->pos.zPos);

		if (item->pos.yPos < floorHeight - item->fallspeed)
		{
			if (item->fallspeed + pushable->gravity < 128)
				item->fallspeed += pushable->gravity;
			else
				item->fallspeed = 128;
			item->pos.yPos += item->fallspeed;

			MoveStackY(itemNumber, item->fallspeed);
		}
		else
		{
			item->gravityStatus = false;
			int relY = floorHeight - item->pos.yPos;
			item->pos.yPos = floorHeight;
			if (item->fallspeed >= 128)
				floor_shake_effect(item);
			item->fallspeed = 0;
			SoundEffect(pushable->fallSound, &item->pos, 2);

			MoveStackY(itemNumber, relY);
			AddBridgeStack(itemNumber);

			if (FindStack(itemNumber) == NO_ITEM) // if fallen on some existing pushables, don't test triggers
			{
				roomNumber = item->roomNumber;
				TestTriggersAtXYZ(item->pos.xPos, item->pos.yPos, item->pos.zPos, roomNumber, 1, item->flags & 0x3E00);
			}
			
			RemoveActiveItem(itemNumber);
			item->status = ITEM_NOT_ACTIVE;

			if (pushable->hasFloorCeiling)
			{
				//AlterFloorHeight(item, -((item->triggerFlags - 64) * 256));
				AdjustStopperFlag(item, item->itemFlags[0] + 0x8000, 0);
			}
		}

		return;
	}

	int displaceBox = GetBoundsAccurate(LaraItem)->Z2 - 80; // move pushable based on bbox->Z2 of Lara

	switch (LaraItem->animNumber)
	{
	case LA_PUSHABLE_PUSH:

		if (LaraItem->frameNumber == g_Level.Anims[LaraItem->animNumber].frameBase)
		{
			RemoveFromStack(itemNumber);
			RemoveBridgeStack(itemNumber);
		}

		switch (quadrant) 
		{
		case 0:
			z = pushable->moveZ + displaceBox;
			if (abs(item->pos.zPos - z) < 512 && item->pos.zPos < z)
				item->pos.zPos = z;
			break;

		case 1:
			x = pushable->moveX + displaceBox;
			if (abs(item->pos.xPos - x) < 512 && item->pos.xPos < x)
				item->pos.xPos = x;
			break;

		case 2:
			z = pushable->moveZ - displaceBox;
			if (abs(item->pos.zPos - z) < 512 && item->pos.zPos > z)
				item->pos.zPos = z;
			break;

		case 3:
			x = pushable->moveX - displaceBox;
			if (abs(item->pos.xPos - x) < 512 && item->pos.xPos > x)
				item->pos.xPos = x;
			break;

		default:
			break;
		}

		MoveStackXZ(itemNumber);


		if (LaraItem->frameNumber == g_Level.Anims[LaraItem->animNumber].frameEnd - 1)
		{
			if (pushable->canFall) // check if pushable is about to fall
			{
				roomNumber = item->roomNumber;
				floor = GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &roomNumber);
				if (GetFloorHeight(floor, item->pos.xPos, item->pos.yPos + 10, item->pos.zPos) > item->pos.yPos)
				{
					item->pos.xPos = item->pos.xPos & 0xFFFFFE00 | 0x200;
					item->pos.zPos = item->pos.zPos & 0xFFFFFE00 | 0x200;
					MoveStackXZ(itemNumber);
					//SoundEffect(pushable->stopSound, &item->pos, 2);
					DoPushPull = 0;
					LaraItem->goalAnimState = LS_STOP;

					item->gravityStatus = true; // do fall
					return;
				}
			}


			if (TrInput & IN_ACTION)
			{
				if (!TestBlockPush(item, blockHeight, quadrant))
				{
					LaraItem->goalAnimState = LS_STOP;
				}
				else
				{
					TestTriggersAtXYZ(item->pos.xPos, item->pos.yPos, item->pos.zPos, item->roomNumber, 1, item->flags & 0x3E00);
					pushable->moveX = item->pos.xPos;
					pushable->moveZ = item->pos.zPos;
				}
			}
			else
			{
				LaraItem->goalAnimState = LS_STOP;
			}
		}
		break;

	case LA_PUSHABLE_PULL:

		if (LaraItem->frameNumber == g_Level.Anims[LaraItem->animNumber].frameBase)
		{
			RemoveFromStack(itemNumber);
			RemoveBridgeStack(itemNumber);
		}

		switch (quadrant)
		{
		case NORTH:
			z = pushable->moveZ + displaceBox;
			if (abs(item->pos.zPos - z) < 512 && item->pos.zPos > z)
				item->pos.zPos = z;
			break;

		case EAST:
			x = pushable->moveX + displaceBox;
			if (abs(item->pos.xPos - x) < 512 && item->pos.xPos > x)
				item->pos.xPos = x;
			break;

		case SOUTH:
			z = pushable->moveZ - displaceBox;
			if (abs(item->pos.zPos - z) < 512 && item->pos.zPos < z)
				item->pos.zPos = z;
			break;

		case WEST:
			x = pushable->moveX - displaceBox;
			if (abs(item->pos.xPos - x) < 512 && item->pos.xPos < x)
				item->pos.xPos = x;
			break;

		default:
			break;
		}

		MoveStackXZ(itemNumber);

		if (LaraItem->frameNumber == g_Level.Anims[LaraItem->animNumber].frameEnd - 1)
		{
			if (TrInput & IN_ACTION)
			{
				if (!TestBlockPull(item, blockHeight, quadrant))
				{
					LaraItem->goalAnimState = LS_STOP;
				}
				else
				{
					TestTriggersAtXYZ(item->pos.xPos, item->pos.yPos, item->pos.zPos, item->roomNumber, 1, item->flags & 0x3E00);
					pushable->moveX = item->pos.xPos;
					pushable->moveZ = item->pos.zPos;
				}
			}
			else
			{
				LaraItem->goalAnimState = LS_STOP;
			}
		}
		break;

	case LA_PUSHABLE_PUSH_TO_STAND:
	case LA_PUSHABLE_PULL_TO_STAND:
		if (LaraItem->frameNumber == g_Level.Anims[LA_PUSHABLE_PUSH_TO_STAND].frameBase
			|| LaraItem->frameNumber == g_Level.Anims[LA_PUSHABLE_PULL_TO_STAND].frameBase)
		{
			item->pos.xPos = item->pos.xPos & 0xFFFFFE00 | 0x200;
			item->pos.zPos = item->pos.zPos & 0xFFFFFE00 | 0x200;

			MoveStackXZ(itemNumber);
			FindStack(itemNumber);
			AddBridgeStack(itemNumber);

			roomNumber = item->roomNumber;
			TestTriggersAtXYZ(item->pos.xPos, item->pos.yPos, item->pos.zPos, roomNumber, 1, item->flags & 0x3E00);
		}

		if (LaraItem->frameNumber == g_Level.Anims[LaraItem->animNumber].frameEnd)
		{
			RemoveActiveItem(itemNumber);
			item->status = ITEM_NOT_ACTIVE;

			if (pushable->hasFloorCeiling)
			{
				//AlterFloorHeight(item, -((item->triggerFlags - 64) * 256));
				AdjustStopperFlag(item, item->itemFlags[0] + 0x8000, 0);
			}
		}

		break;
	}
}

void PushableBlockCollision(short itemNum, ITEM_INFO* l, COLL_INFO* coll)
{
	ITEM_INFO* item = &g_Level.Items[itemNum];

	short roomNumber = item->roomNumber;
	FLOOR_INFO* floor = GetFloor(item->pos.xPos, item->pos.yPos - 256, item->pos.zPos, &roomNumber);
	PUSHABLE_INFO* pushable = GET_PUSHABLEINFO(item);

	int blockHeight = GetStackHeight(item);
	
	if ((!(TrInput & IN_ACTION)
		|| l->currentAnimState != LS_STOP
		|| l->animNumber != LA_STAND_IDLE
		|| l->gravityStatus
		|| Lara.gunStatus
		|| item->status == ITEM_INVISIBLE
		|| item->triggerFlags < 0)
		&& (!Lara.isMoving || Lara.generalPtr != item))
	{
		if ((l->currentAnimState != LS_PUSHABLE_GRAB
			|| (l->frameNumber != g_Level.Anims[LA_PUSHABLE_GRAB].frameBase + 19)
			|| Lara.cornerX != (int)item))
		{
			if (!pushable->hasFloorCeiling)
				ObjectCollision(itemNum, l, coll);
			return;
		}

		short quadrant = (unsigned short)(LaraItem->pos.yRot + ANGLE(45)) / ANGLE(90);

		bool quadrantDisabled = false;
		switch (quadrant)
		{
		case NORTH:
			quadrantDisabled = pushable->disableN;
			break;
		case EAST:
			quadrantDisabled = pushable->disableE;
			break;
		case SOUTH:
			quadrantDisabled = pushable->disableS;
			break;
		case WEST:
			quadrantDisabled = pushable->disableW;
			break;
		}

		if (quadrantDisabled)
			return;

		if (!CheckStackLimit(item))
			return;

		if (TrInput & IN_FORWARD)
		{
			if (!TestBlockPush(item, blockHeight, quadrant) || pushable->disablePush)
				return;
			l->goalAnimState = LS_PUSHABLE_PUSH;
		}
		else if (TrInput & IN_BACK)
		{
			if (!TestBlockPull(item, blockHeight, quadrant) || pushable->disablePull)
				return;
			l->goalAnimState = LS_PUSHABLE_PULL;
		}
		else
		{
			return;
		}

		item->status = ITEM_ACTIVE;
		AddActiveItem(itemNum);
		Lara.headYrot = 0;
		Lara.headXrot = 0;
		Lara.torsoYrot = 0;
		Lara.torsoXrot = 0;
		
		pushable->moveX = item->pos.xPos;
		pushable->moveZ = item->pos.zPos;

		if (pushable->hasFloorCeiling)
		{
			//AlterFloorHeight(item, ((item->triggerFlags - 64) * 256));
			AdjustStopperFlag(item, item->itemFlags[0], 0);
		}
	}
	else
	{
		BOUNDING_BOX* bounds = GetBoundsAccurate(item);

		PushableBlockBounds.boundingBox.X1 = (bounds->X1 / 2) - 100;
		PushableBlockBounds.boundingBox.X2 = (bounds->X2 / 2) + 100;
		PushableBlockBounds.boundingBox.Z1 = bounds->Z1 - 200;
		PushableBlockBounds.boundingBox.Z2 = 0;

		short rot = item->pos.yRot;
		item->pos.yRot = (l->pos.yRot + ANGLE(45)) & 0xC000;

		if (TestLaraPosition(&PushableBlockBounds, item, l))
		{
			unsigned short quadrant = (unsigned short)((item->pos.yRot / 0x4000) + ((rot + 0x2000) / 0x4000));
			if (quadrant & 1)
				PushableBlockPos.z = bounds->X1 - 35;
			else
				PushableBlockPos.z = bounds->Z1 - 35;

			if (pushable->hasFloorCeiling)
			{					
				// For now don't use auto-align function because it can collide with climb up moves of Lara

				LaraItem->pos.xRot = item->pos.xRot;
				LaraItem->pos.yRot = item->pos.yRot;
				LaraItem->pos.zRot = item->pos.zRot;

				l->animNumber = LA_PUSHABLE_GRAB;
				l->frameNumber = g_Level.Anims[l->animNumber].frameBase;
				l->currentAnimState = LS_PUSHABLE_GRAB;
				l->goalAnimState = LS_PUSHABLE_GRAB;
				Lara.isMoving = false;
				Lara.gunStatus = LG_HANDS_BUSY;
				Lara.cornerX = (int)item;
				item->pos.yRot = rot;
			}
			else
			{
				if (MoveLaraPosition(&PushableBlockPos, item, l))
				{
					l->animNumber = LA_PUSHABLE_GRAB;
					l->frameNumber = g_Level.Anims[l->animNumber].frameBase;
					l->currentAnimState = LS_PUSHABLE_GRAB;
					l->goalAnimState = LS_PUSHABLE_GRAB;
					Lara.isMoving = false;
					Lara.gunStatus = LG_HANDS_BUSY;
					Lara.cornerX = (int)item;
					item->pos.yRot = rot;
				}
				else
				{
					Lara.generalPtr = item;
					item->pos.yRot = rot;
				}
			}
		}
		else
		{
			if (Lara.isMoving && Lara.generalPtr == item)
			{
				Lara.isMoving = false;
				Lara.gunStatus = LG_NO_ARMS;
			}
			item->pos.yRot = rot;
		}
	}
}

void pushLoop(ITEM_INFO* item) // Do Flipeffect 18 in anims
{
	DoPushPull = 1;
}

void pushEnd(ITEM_INFO* item) // Do Flipeffect 19 in anims
{
	if (DoPushPull == 1)
	{
		DoPushPull = -1;
	}
}

int TestBlockMovable(ITEM_INFO* item, int blokhite)
{
	short roomNumber = item->roomNumber;
	FLOOR_INFO* floor = GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &roomNumber);
	if (floor->floor == NO_HEIGHT / 256)
		return 1;

	if (floor->floor * 256 != item->pos.yPos - blokhite)
		return 0;

	return 1;
}

int TestBlockPush(ITEM_INFO* item, int blockhite, unsigned short quadrant)
{
	int x = item->pos.xPos;
	int y = item->pos.yPos;
	int z = item->pos.zPos;

	short roomNum = item->roomNumber;
	switch (quadrant)
	{
	case NORTH:
		z += 1024;
		break;

	case EAST:
		x += 1024;
		break;

	case SOUTH:
		z -= 1024;
		break;

	case WEST:
		x -= 1024;
		break;
	}

	FLOOR_INFO* floor = GetFloor(x, y - blockhite, z, &roomNum);
	ROOM_INFO* r = &g_Level.Rooms[roomNum];
	if (XZ_GET_SECTOR(r, x - r->x, z - r->z).stopper)
		return 0;

	int floorHeight = GetFloorHeight(floor, x, y - blockhite, z);
	if (HeightType)
		return 0;

	if (GET_PUSHABLEINFO(item)->canFall)
	{
		if (floorHeight < y)
			return 0;
	}
	else
	{
		if (floorHeight != y)
			return 0;
	}
	

	int ceiling = y - blockhite + 100;
	floor = GetFloor(x, ceiling, z, &roomNum);
	if (GetCeiling(floor, x, ceiling, z) > ceiling)
		return 0;

	int oldX = item->pos.xPos;
	int oldZ = item->pos.zPos;
	item->pos.xPos = x;
	item->pos.zPos = z;
	GetCollidedObjects(item, 256, 1, &CollidedItems[0], 0, 1);
	item->pos.xPos = oldX;
	item->pos.zPos = oldZ;

	int i = 0;
	while (CollidedItems[i] != NULL)
	{
		if (Objects[CollidedItems[i]->objectNumber].floor == NULL)
			return 0;
		i++;
	}
	return 1;
}

int TestBlockPull(ITEM_INFO* item, int blockhite, short quadrant)
{
	int xadd = 0;
	int zadd = 0;

	switch (quadrant)
	{
	case NORTH:
		zadd = -1024;
		break;

	case EAST:
		xadd = -1024;
		break;

	case SOUTH:
		zadd = 1024;
		break;

	case WEST:
		xadd = 1024;
		break;
	}

	int x = item->pos.xPos + xadd;
	int y = item->pos.yPos;
	int z = item->pos.zPos + zadd;
	short roomNum = item->roomNumber;
	FLOOR_INFO* floor = GetFloor(x, y - blockhite, z, &roomNum);

	ROOM_INFO* r = &g_Level.Rooms[roomNum];
	if (XZ_GET_SECTOR(r, x - r->x, z - r->z).stopper)
		return 0;

	if (GetFloorHeight(floor, x, y - blockhite, z) != y)
		return 0;

	if (floor->ceiling * 256 > y - blockhite)
		return 0;

	int oldX = item->pos.xPos;
	int oldZ = item->pos.zPos;
	item->pos.xPos = x;
	item->pos.zPos = z;
	GetCollidedObjects(item, 256, 1, &CollidedItems[0], 0, 1);
	item->pos.xPos = oldX;
	item->pos.zPos = oldZ;

	int i = 0;
	while (CollidedItems[i] != NULL)
	{
		if (Objects[CollidedItems[i]->objectNumber].floor == NULL)
			return 0;
		i++;
	}

	x += xadd;
	z += zadd;
	roomNum = item->roomNumber;
	floor = GetFloor(x, y - blockhite, z, &roomNum);

	if (GetFloorHeight(floor, x, y - blockhite, z) != y)
		return 0;

	if (floor->ceiling * 256 > y - LARA_HITE)
		return 0;

	x = LaraItem->pos.xPos + xadd;
	z = LaraItem->pos.zPos + zadd;

	roomNum = LaraItem->roomNumber;
	GetFloor(x, y, z, &roomNum);

	r = &g_Level.Rooms[roomNum];
	if (XZ_GET_SECTOR(r, x - r->x, z - r->z).stopper)
		return 0;

	oldX = LaraItem->pos.xPos;
	oldZ = LaraItem->pos.zPos;
	LaraItem->pos.xPos = x;
	LaraItem->pos.zPos = z;
	GetCollidedObjects(LaraItem, 256, 1, &CollidedItems[0], 0, 1);
	LaraItem->pos.xPos = oldX;
	LaraItem->pos.zPos = oldZ;

	i = 0;
	while (CollidedItems[i] != NULL)
	{
		if (Objects[CollidedItems[i]->objectNumber].floor == NULL)
			return 0;
		i++;
	}
	return 1;
}

void MoveStackXZ(short itemNum)
{
	auto item = &g_Level.Items[itemNum];

	short newRoomNumber = item->roomNumber;
	GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &newRoomNumber);
	if (newRoomNumber != item->roomNumber)
		ItemNewRoom(itemNum, newRoomNumber);

	auto stackItem = item;
	while (stackItem->itemFlags[1] != NO_ITEM) // move pushblock stack together with bottom pushblock
	{
		int stackIndex = stackItem->itemFlags[1];
		stackItem = &g_Level.Items[stackIndex];

		stackItem->pos.xPos = item->pos.xPos;
		stackItem->pos.zPos = item->pos.zPos;

		newRoomNumber = stackItem->roomNumber;
		GetFloor(stackItem->pos.xPos, stackItem->pos.yPos, stackItem->pos.zPos, &newRoomNumber);
		if (newRoomNumber != stackItem->roomNumber)
			ItemNewRoom(stackIndex, newRoomNumber);
	}
}

void MoveStackY(short itemNum, int y)
{
	auto item = &g_Level.Items[itemNum];

	short newRoomNumber = item->roomNumber;
	GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &newRoomNumber);
	if (newRoomNumber != item->roomNumber)
		ItemNewRoom(itemNum, newRoomNumber);

	while (item->itemFlags[1] != NO_ITEM) // move pushblock stack together with bottom pushblock
	{
		int stackIndex = item->itemFlags[1];
		item = &g_Level.Items[stackIndex];

		item->pos.yPos += y;

		short newRoomNumber = item->roomNumber;
		GetFloor(item->pos.xPos, item->pos.yPos, item->pos.zPos, &newRoomNumber);
		if (newRoomNumber != item->roomNumber)
			ItemNewRoom(stackIndex, newRoomNumber);
	}
}

void AddBridgeStack(short itemNum)
{
	auto item = &g_Level.Items[itemNum];

	if (GET_PUSHABLEINFO(item)->hasFloorCeiling)
		T5M::Floordata::AddBridge(itemNum);

	int stackIndex = g_Level.Items[itemNum].itemFlags[1];
	while (stackIndex != NO_ITEM)
	{
		auto stackItem = &g_Level.Items[stackIndex];

		if (GET_PUSHABLEINFO(stackItem)->hasFloorCeiling)
			T5M::Floordata::AddBridge(stackIndex);

		stackIndex = g_Level.Items[stackIndex].itemFlags[1];
	}
}

void RemoveBridgeStack(short itemNum)
{
	auto item = &g_Level.Items[itemNum];

	if (GET_PUSHABLEINFO(item)->hasFloorCeiling)
		T5M::Floordata::RemoveBridge(itemNum);

	int stackIndex = g_Level.Items[itemNum].itemFlags[1];
	while (stackIndex != NO_ITEM)
	{
		auto stackItem = &g_Level.Items[stackIndex];

		if (GET_PUSHABLEINFO(stackItem)->hasFloorCeiling)
			T5M::Floordata::RemoveBridge(stackIndex);

		stackIndex = g_Level.Items[stackIndex].itemFlags[1];
	}
}

void RemoveFromStack(short itemNum) // unlink pushable from stack if linked
{
	for (int i = 0; i < g_Level.NumItems; i++)
	{
		if (i == itemNum)
			continue;

		auto belowItem = &g_Level.Items[i];

		int objectNum = belowItem->objectNumber;
		if (objectNum >= ID_PUSHABLE_OBJECT1 && objectNum <= ID_PUSHABLE_OBJECT10)
		{
			if (belowItem->itemFlags[1] == itemNum)
				belowItem->itemFlags[1] = NO_ITEM;
		}
	}
}

int FindStack(short itemNum)
{
	int stackTop = NO_ITEM; // index of heighest (yPos) pushable in stack
	int stackYmin = CLICK(256); // set starting height

	//Check for pushable directly below current one in same sector
	for (int i = 0; i < g_Level.NumItems; i++)
	{
		if (i == itemNum)
			continue;

		auto belowItem = &g_Level.Items[i];

		int objectNum = belowItem->objectNumber;
		if (objectNum >= ID_PUSHABLE_OBJECT1 && objectNum <= ID_PUSHABLE_OBJECT10)
		{
			auto item = &g_Level.Items[itemNum];
			int x = item->pos.xPos;
			int y = item->pos.yPos;
			int z = item->pos.zPos;

			if (belowItem->pos.xPos == x && belowItem->pos.zPos == z)
			{
				int belowY = belowItem->pos.yPos;
				if (belowY > y && belowY < stackYmin)
				{
					// set heighest pushable so far as top of stack
					stackTop = i;
					stackYmin = belowItem->pos.yPos;
				}
			}
		}
	}

	if (stackTop != NO_ITEM)
		g_Level.Items[stackTop].itemFlags[1] = itemNum;

	return stackTop;
}

int GetStackHeight(ITEM_INFO* item)
{
	int height = GET_PUSHABLEINFO(item)->height;

	auto stackItem = item;
	while (stackItem->itemFlags[1] != NO_ITEM)
	{
		stackItem = &g_Level.Items[stackItem->itemFlags[1]];
		height += GET_PUSHABLEINFO(stackItem)->height;
	}

	return height;
}

bool CheckStackLimit(ITEM_INFO* item)
{
	int limit = GET_PUSHABLEINFO(item)->stackLimit;
	
	int count = 1;
	auto stackItem = item;
	while (stackItem->itemFlags[1] != NO_ITEM)
	{
		stackItem = &g_Level.Items[stackItem->itemFlags[1]];
		count++;

		if (count > limit)
			return false;
	}

	return true;
}

std::optional<int> PushableBlockFloor(short itemNumber, int x, int y, int z)
{
	const auto& item = g_Level.Items[itemNumber];
	if (item.status != ITEM_INVISIBLE)
	{
		const auto height = item.pos.yPos - (item.triggerFlags & 0x1F) * CLICK(1);
		return std::optional{height};
	}
	return std::nullopt;
}

std::optional<int> PushableBlockCeiling(short itemNumber, int x, int y, int z)
{
	const auto& item = g_Level.Items[itemNumber];
	if (item.status != ITEM_INVISIBLE)
		return std::optional{item.pos.yPos};
	return std::nullopt;
}

int PushableBlockFloorBorder(short itemNumber)
{
	const auto& item = g_Level.Items[itemNumber];
	const auto height = item.pos.yPos - (item.triggerFlags & 0x1F) * CLICK(1);
	return height;
}

int PushableBlockCeilingBorder(short itemNumber)
{
	const auto& item = g_Level.Items[itemNumber];
	return item.pos.yPos;
}