BlockPiston.cpp

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#include "Globals.h"
#include "BlockPiston.h"
#include "../Item.h"
#include "../World.h"
#include "../Entities/Player.h"
#include "../BlockInServerPluginInterface.h"
#include "ChunkInterface.h"





#define PISTON_MAX_PUSH_DISTANCE 12




cBlockPistonHandler::cBlockPistonHandler(BLOCKTYPE a_BlockType):
    super(a_BlockType)
{
}





void cBlockPistonHandler::OnBroken(
    cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface,
    Vector3i a_BlockPos,
    BLOCKTYPE a_OldBlockType, NIBBLETYPE a_OldBlockMeta
)
{
    // If the piston is extended, destroy the extension as well
    if (IsExtended(a_OldBlockMeta))
    {
        auto extPos = a_BlockPos + MetadataToOffset(a_OldBlockMeta);
        if (a_ChunkInterface.GetBlock(extPos) == E_BLOCK_PISTON_EXTENSION)
        {
            a_ChunkInterface.DropBlockAsPickups(extPos);
        }
    }
}





bool cBlockPistonHandler::GetPlacementBlockTypeMeta(
    cChunkInterface & a_ChunkInterface, cPlayer & a_Player,
    int a_BlockX, int a_BlockY, int a_BlockZ, eBlockFace a_BlockFace,
    int a_CursorX, int a_CursorY, int a_CursorZ,
    BLOCKTYPE & a_BlockType, NIBBLETYPE & a_BlockMeta
)
{
    a_BlockType = m_BlockType;
    a_BlockMeta = RotationPitchToMetaData(a_Player.GetYaw(), a_Player.GetPitch());
    return true;
}





Vector3i cBlockPistonHandler::MetadataToOffset(NIBBLETYPE a_PistonMeta)
{
    switch (a_PistonMeta & 0x07)
    {
        case 0: return Vector3i( 0, -1,  0);
        case 1: return Vector3i( 0,  1,  0);
        case 2: return Vector3i( 0,  0, -1);
        case 3: return Vector3i( 0,  0,  1);
        case 4: return Vector3i(-1,  0,  0);
        case 5: return Vector3i( 1,  0,  0);
        default:
        {
            LOGWARNING("%s: invalid direction %d, ignoring", __FUNCTION__, a_PistonMeta & 0x07);
            ASSERT(!"Invalid direction");
            return Vector3i();
        }
    }
}





void cBlockPistonHandler::PushBlocks(
    const Vector3iSet & a_BlocksToPush,
    cWorld & a_World, const Vector3i & a_PushDir
)
{
    // Sort blocks to move the blocks first, which are farest away from the piston
    // This prevents the overwriting of existing blocks
    std::vector<Vector3i> sortedBlocks(a_BlocksToPush.begin(), a_BlocksToPush.end());
    std::sort(sortedBlocks.begin(), sortedBlocks.end(), [a_PushDir](const Vector3i & a, const Vector3i & b)
    {
        return (a.Dot(a_PushDir) > b.Dot(a_PushDir));
    });

    // Move every block
    BLOCKTYPE moveBlock;
    NIBBLETYPE moveMeta;
    for (auto & moveBlockPos : sortedBlocks)
    {
        a_World.GetBlockTypeMeta(moveBlockPos.x, moveBlockPos.y, moveBlockPos.z, moveBlock, moveMeta);

        if (cBlockInfo::IsPistonBreakable(moveBlock))
        {
            // Block is breakable, drop it:
            a_World.DropBlockAsPickups(moveBlockPos, nullptr, nullptr);
        }
        else
        {
            // Not breakable, just move it
            a_World.SetBlock(moveBlockPos.x, moveBlockPos.y, moveBlockPos.z, E_BLOCK_AIR, 0);
            moveBlockPos += a_PushDir;
            a_World.SetBlock(moveBlockPos.x, moveBlockPos.y, moveBlockPos.z, moveBlock, moveMeta);
        }
    }
}





bool cBlockPistonHandler::CanPushBlock(
    const Vector3i & a_BlockPos, cWorld & a_World, bool a_RequirePushable,
    Vector3iSet & a_BlocksPushed, const Vector3i & a_PushDir
)
{
    const static std::array<Vector3i, 6> pushingDirs =
    {
        {
            Vector3i(-1,  0,  0), Vector3i(1, 0, 0),
            Vector3i( 0, -1,  0), Vector3i(0, 1, 0),
            Vector3i( 0,  0, -1), Vector3i(0, 0, 1)
        }
    };

    BLOCKTYPE currBlock;
    NIBBLETYPE currMeta;
    a_World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, currBlock, currMeta);

    if (currBlock == E_BLOCK_AIR)
    {
        // Air can be pushed
        return true;
    }

    if (!a_RequirePushable && cBlockInfo::IsPistonBreakable(currBlock))
    {
        // Block should not be broken, when it's not in the pushing direction
        return true;
    }

    if (!CanPush(currBlock, currMeta))
    {
        // When it's not required to push this block, don't fail
        return !a_RequirePushable;
    }

    if (a_BlocksPushed.size() >= PISTON_MAX_PUSH_DISTANCE)
    {
        // Do not allow to push too much blocks
        return false;
    }

    if (!a_BlocksPushed.insert(a_BlockPos).second || cBlockInfo::IsPistonBreakable(currBlock))
    {
        return true;  // Element exist already
    }

    if (currBlock == E_BLOCK_SLIME_BLOCK)
    {
        // Try to push the other directions
        for (const auto & testDir : pushingDirs)
        {
            if (!CanPushBlock(a_BlockPos + testDir, a_World, false, a_BlocksPushed, a_PushDir))
            {
                // When it's not possible for a direction, then fail
                return false;
            }
        }
    }

    // Try to push the block in front of this block
    return CanPushBlock(a_BlockPos + a_PushDir, a_World, true, a_BlocksPushed, a_PushDir);
}





void cBlockPistonHandler::ExtendPiston(Vector3i a_BlockPos, cWorld & a_World)
{
    {
        // Broadcast block action first. Will do nothing if piston cannot in fact push

        BLOCKTYPE pistonBlock;
        NIBBLETYPE pistonMeta;
        a_World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
        a_World.BroadcastBlockAction(a_BlockPos, PistonExtendAction, pistonMeta, pistonBlock);
    }

    // Client expects the server to "play" the animation before setting the final blocks
    // However, we don't confuse animation with the underlying state of the world, so emulate by delaying 1 tick
    // (Probably why vanilla has so many dupe glitches with sand and pistons lolol)

    a_World.ScheduleTask(1, [a_BlockPos](cWorld & World)
        {
            BLOCKTYPE pistonBlock;
            NIBBLETYPE pistonMeta;
            World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);

            if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
            {
                // Ensure we operate on a piston to avoid spurious behaviour
                // Note that the scheduled task may result in the block type of a_BlockPos changing
                return;
            }

            if (IsExtended(pistonMeta))
            {
                // Already extended, bail out
                return;
            }

            Vector3i pushDir = MetadataToOffset(pistonMeta);
            Vector3iSet blocksPushed;
            if (!CanPushBlock(a_BlockPos + pushDir, World, true, blocksPushed, pushDir))
            {
                // Can't push anything, bail out
                return;
            }
            PushBlocks(blocksPushed, World, pushDir);

            // Set the extension and the piston base correctly
            Vector3i extensionPos = a_BlockPos + pushDir;
            World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta | 0x8);
            World.SetBlock(
                extensionPos.x, extensionPos.y, extensionPos.z,
                E_BLOCK_PISTON_EXTENSION, pistonMeta | (IsSticky(pistonBlock) ? 8 : 0)
            );

            // Play sound effect only if extended successfully
            World.BroadcastSoundEffect("block.piston.extend", a_BlockPos, 0.5f, 0.7f);
        }
    );
}





void cBlockPistonHandler::RetractPiston(Vector3i a_BlockPos, cWorld & a_World)
{
    {
        BLOCKTYPE pistonBlock;
        NIBBLETYPE pistonMeta;
        a_World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);
        a_World.BroadcastBlockAction(a_BlockPos, PistonRetractAction, pistonMeta, pistonBlock);
    }

    a_World.ScheduleTask(1, [a_BlockPos](cWorld & World)
        {
            BLOCKTYPE pistonBlock;
            NIBBLETYPE pistonMeta;
            World.GetBlockTypeMeta(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta);

            if ((pistonBlock != E_BLOCK_PISTON) && !IsSticky(pistonBlock))
            {
                // Ensure we operate on a piston to avoid spurious behaviour
                // Note that the scheduled task may result in the block type of a_BlockPos changing
                return;
            }

            if (!IsExtended(pistonMeta))
            {
                // Already retracted, bail out
                return;
            }

            Vector3i pushDir = MetadataToOffset(pistonMeta);

            // Check the extension:
            Vector3i extensionPos = a_BlockPos + pushDir;
            if (World.GetBlock(extensionPos) != E_BLOCK_PISTON_EXTENSION)
            {
                LOGD("%s: Piston without an extension - still extending, or just in an invalid state?", __FUNCTION__);
                return;
            }

            // Remove extension, update base state
            World.SetBlock(extensionPos.x, extensionPos.y, extensionPos.z, E_BLOCK_AIR, 0);
            World.SetBlock(a_BlockPos.x, a_BlockPos.y, a_BlockPos.z, pistonBlock, pistonMeta & ~(8));

            // (Retraction is always successful, but play in the task for consistency)
            World.BroadcastSoundEffect("block.piston.contract", a_BlockPos, 0.5f, 0.7f);

            if (!IsSticky(pistonBlock))
            {
                // No need for block pulling, bail out
                return;
            }

            // Get the block to pull
            Vector3i AdjustedPosition = a_BlockPos + pushDir * 2;
            // Try to "push" the pulling block in the opposite direction
            pushDir *= -1;

            Vector3iSet pushedBlocks;
            if (!CanPushBlock(AdjustedPosition, World, false, pushedBlocks, pushDir))
            {
                // Not pushable, bail out
                return;
            }

            PushBlocks(pushedBlocks, World, pushDir);
        }
    );
}





// cBlockPistonHeadHandler:

cBlockPistonHeadHandler::cBlockPistonHeadHandler(void) :
    super(E_BLOCK_PISTON_EXTENSION)
{
}





void cBlockPistonHeadHandler::OnBroken(
    cChunkInterface & a_ChunkInterface, cWorldInterface & a_WorldInterface,
    Vector3i a_BlockPos,
    BLOCKTYPE a_OldBlockType, NIBBLETYPE a_OldBlockMeta
)
{
    // Drop the base of the piston:
    auto basePos = a_BlockPos - cBlockPistonHandler::MetadataToOffset(a_OldBlockMeta);
    if (cChunkDef::IsValidHeight(basePos.y))
    {
        a_ChunkInterface.DropBlockAsPickups(basePos);
    }
}