removeWater

local Terrain = workspace.Terrain
local processBlockSize = 640
local WATER = Enum.Material.Water
local AIR = Enum.Material.Air
local floor = math.floor

function isInRegion3(region, point)
    local relative = (point - region.CFrame.p) / region.Size
    return -0.5 <= relative.X and relative.X <= 0.5
       and -0.5 <= relative.Y and relative.Y <= 0.5
       and -0.5 <= relative.Z and relative.Z <= 0.5
end

local function round(num)
    return math.floor(num + .5)
end

local function getAlignedPosition(pos)
    local x = round(pos.X)
    x = x - x%4 + 2
    local y = round(pos.Y)
    y = y - y%4 + 2
    local z = round(pos.Z)
    z = z - z%4 + 2

    return Vector3.new(x,y,z)
end

local function comma_value(n)
    local left,num,right = string.match(n,'^([^%d]*%d)(%d*)(.-)$')
    return left..(num:reverse():gsub('(%d%d%d)','%1,'):reverse())..right
end

local function removeWater(voxelPos, worldSize)
    local functionStart = tick()
    voxelPos = getAlignedPosition(voxelPos)
    local material = nil
    local occupancy = nil

    local boundaryRegion = Region3.new(voxelPos-worldSize/2, voxelPos+worldSize/2)
    boundaryRegion:ExpandToGrid(4)
    local minPoint = boundaryRegion.CFrame.p-boundaryRegion.Size/2
    print("Starting")
    local partsProcessed = 0

    local regions = {}

    local start = getAlignedPosition(minPoint)
    local xOffset = 0
    local yOffset = 0
    local zOffset = 0
    local done = false
    repeat
        local startPos = start+Vector3.new(xOffset,yOffset,zOffset)
        local size = boundaryRegion.CFrame.p+boundaryRegion.Size/2-startPos
        local x,y,z = size.X, size.Y, size.Z
        if x > processBlockSize then
            x = processBlockSize
        end
        if y > processBlockSize then
            y = processBlockSize
        end
        if z > processBlockSize then
            z = processBlockSize
        end
        size = Vector3.new(x,y,z)
        local region = Region3.new(startPos, startPos+size)
        region = region:ExpandToGrid(4)
        table.insert(regions, region)
        zOffset = zOffset + processBlockSize
        if zOffset >= boundaryRegion.Size.Z then
            zOffset = 0
            yOffset = yOffset + processBlockSize
        end
        if yOffset >= boundaryRegion.Size.Y then
            yOffset = 0
            xOffset = xOffset + processBlockSize
        end
        if xOffset >= boundaryRegion.Size.X then
            done = true
        end
    until done

    print("Writing to ", #regions, " regions!")
    print("Removing water...")
    local totalRemoved = 0
    local totalProcessed = 0
    local totalVolume = worldSize.X*worldSize.Y*worldSize.Z
    local changed,materials,occupancy,size,matsX,occX,matsY,occY,p
    for index, region in pairs(regions) do
        changed = 0
        materials, occupancy = Terrain:ReadVoxels(region, 4)
        size = materials.Size
        for x = 1, size.X do
            matsX = materials[x]
            occX = occupancy[x]
            for y = 1, size.Y do
                matsY = matsX[y]
                occY = occX[y]
                for z = 1, size.Z do
                    totalProcessed = totalProcessed + 1
                    if matsY[z] == WATER then
                        matsY[z] = AIR
                        occY[z] = 0
                        changed = changed + 1
                    end
                end
            end
        end

        if changed > 0 then
            Terrain:WriteVoxels(region, 4, materials, occupancy)
        end
        if index%4 == 0 then
            print((floor(index/#regions*1000+0.5)/10).."% complete!")
            wait(0)
        end
        totalRemoved = totalRemoved + changed
    end

end

removeWater(Vector3.new(0,0,0), Vector3.new(3000,2000,3000))