ItemEyeOfEnder.h

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#pragma once
 
#include "ItemHandler.h"
#include "ItemThrowable.h"
 
 
 
 
 
class cItemEyeOfEnderHandler final:
    public cItemThrowableHandler
{
    using Super = cItemThrowableHandler;
 
public:
 
    constexpr cItemEyeOfEnderHandler(int a_ItemType):
        Super(a_ItemType, cProjectileEntity::pkSnowball, 30)
    {
    }
 
 
 
 
 
    virtual bool OnItemUse(
        cWorld * a_World, cPlayer * a_Player, cBlockPluginInterface & a_PluginInterface, const cItem & a_Item,
        const Vector3i a_ClickedBlockPos,
        eBlockFace a_ClickedBlockFace
    ) const override
    {
        // Try to fill an End Portal Frame block:
        if (a_ClickedBlockFace != BLOCK_FACE_NONE)
        {
            BLOCKTYPE FacingBlock;
            NIBBLETYPE FacingMeta;
            a_World->GetBlockTypeMeta(a_ClickedBlockPos, FacingBlock, FacingMeta);
            if (FacingBlock == E_BLOCK_END_PORTAL_FRAME)
            {
                // Fill the portal frame. E_META_END_PORTAL_EYE is the bit for holding the eye of ender.
                if ((FacingMeta & E_META_END_PORTAL_FRAME_EYE) != E_META_END_PORTAL_FRAME_EYE)
                {
                    a_World->SetBlock(a_ClickedBlockPos, E_BLOCK_END_PORTAL_FRAME, FacingMeta | E_META_END_PORTAL_FRAME_EYE);
                    if (!a_Player->IsGameModeCreative())
                    {
                        a_Player->GetInventory().RemoveOneEquippedItem();
                    }
 
                    cChunkInterface ChunkInterface(a_World->GetChunkMap());
 
                    // Try to spawn portal:
                    FindAndSetPortal(a_ClickedBlockPos, FacingMeta & 3, ChunkInterface, *a_World);
                    return true;
                }
            }
            return false;
        }
 
        // TODO: Create projectile for Eye Of Ender
        // return Super::OnItemUse(a_World, a_Player, a_PluginInterface, a_Item, a_ClickedBlockPos, a_ClickedBlockFace);
 
        return false;
    }
 
 
 
 
    static bool FindAndSetPortal(Vector3i a_FirstFrame, NIBBLETYPE a_Direction, cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface)
    {
        /*
        PORTAL FINDING ALGORITH
        =======================
        - Get clicked base block
        - Check diagonally (clockwise) for another portal block
            - if exists, and has eye, Continue. Abort if any are facing the wrong direction.
            - if doesn't exist, check horizontally (the block to the left of this block). Abort if there is no horizontal block.
        - After a corner has been met, traverse the portal clockwise, ensuring valid portal frames connect the rectangle.
        - Track the NorthWest Corner, and the dimensions.
        - If dimensions are valid, create the portal.
        */
 
        static_assert((E_META_END_PORTAL_FRAME_ZM - E_META_END_PORTAL_FRAME_XM) == 1, "Should be going clockwise");
 
        const int MIN_PORTAL_WIDTH = 3;
        const int MAX_PORTAL_WIDTH = 4;
 
        // Directions to use for the clockwise traversal.
        static const Vector3i Left[] =
        {
            { 1, 0,  0},  // 0, South, left block is East  / XP
            { 0, 0,  1},  // 1, West,  left block is South / ZP
            {-1, 0,  0},  // 2, North, left block is West  / XM
            { 0, 0, -1},  // 3, East,  left block is North / ZM
        };
        static const Vector3i LeftForward[] =
        {
            { 1, 0,  1},  // 0, South, left block is SouthEast / XP ZP
            {-1, 0,  1},  // 1, West,  left block is SouthWest / XM ZP
            {-1, 0, -1},  // 2, North, left block is NorthWest / XM ZM
            { 1, 0, -1},  // 3, East,  left block is NorthEast / XP ZM
        };
 
 
        int EdgesComplete = -1;  // We start search _before_ finding the first edge
        Vector3i NorthWestCorner;
        int EdgeWidth[4] = { 1, 1, 1, 1 };
        NIBBLETYPE CurrentDirection = a_Direction;
        Vector3i CurrentPos = a_FirstFrame;
 
        // Scan clockwise until we have seen all 4 edges
        while (EdgesComplete < 4)
        {
            // Check if we are at a corner
            Vector3i NextPos = CurrentPos + LeftForward[CurrentDirection];
            if (IsPortalFrame(a_ChunkInterface.GetBlock(NextPos)))
            {
                // We have found the corner, move clockwise to next edge
                if (CurrentDirection == E_META_END_PORTAL_FRAME_XP)
                {
                    // We are on the NW (XM, ZM) Corner
                    // Relative to the previous frame, the portal should appear to the right of this portal frame.
                    NorthWestCorner = NextPos - Left[CurrentDirection];
                }
 
                if (EdgesComplete == -1)
                {
                    // Reset current width, we will revisit it last
                    EdgeWidth[CurrentDirection] = 1;
                }
 
                // Rotate 90 degrees clockwise
                CurrentDirection = (CurrentDirection + 1) % 4;
                EdgesComplete++;
            }
            else
            {
                // We are not at a corner, keep walking the edge
                NextPos = CurrentPos + Left[CurrentDirection];
 
                EdgeWidth[CurrentDirection]++;
                if (EdgeWidth[CurrentDirection] > MAX_PORTAL_WIDTH)
                {
                    // Don't build a portal that is too long.
                    return false;
                }
            }
 
            if (!IsValidFrameAtPos(a_ChunkInterface, NextPos, CurrentDirection))
            {
                // Neither the edge nor the corner are valid portal blocks.
                return false;
            }
 
            CurrentPos = NextPos;
        }
 
        if ((EdgeWidth[0] != EdgeWidth[2]) || (EdgeWidth[1] != EdgeWidth[3]))
        {
            // Mismatched Portal Dimensions.
            return false;
        }
        if ((EdgeWidth[0] < MIN_PORTAL_WIDTH) || (EdgeWidth[1] < MIN_PORTAL_WIDTH))
        {
            // Portal too small.
            return false;
        }
 
        for (int i = 0; i < EdgeWidth[0]; i++)
        {
            for (int j = 0; j < EdgeWidth[1]; j++)
            {
                a_ChunkInterface.SetBlock(NorthWestCorner.x + i, NorthWestCorner.y, NorthWestCorner.z + j, E_BLOCK_END_PORTAL, 0);
            }
        }
        return true;
    }
 
 
 
 
 
    static bool IsValidFrameAtPos(cChunkInterface & a_ChunkInterface, Vector3i a_BlockPos, NIBBLETYPE a_ShouldFace)
    {
        BLOCKTYPE BlockType;
        NIBBLETYPE BlockMeta;
 
        return (
            a_ChunkInterface.GetBlockTypeMeta(a_BlockPos, BlockType, BlockMeta) &&
            (BlockType == E_BLOCK_END_PORTAL_FRAME) &&
            (BlockMeta == (a_ShouldFace | E_META_END_PORTAL_FRAME_EYE))
        );
    }
 
 
 
 
    static bool IsPortalFrame(BLOCKTYPE BlockType)
    {
        return (BlockType == E_BLOCK_END_PORTAL_FRAME);
    }
} ;