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spatial.lua
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spatial.lua
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-- Spatial - A minimal spacial hashing library for lua.
-- Version 2.0
--
-- MIT License
--
-- Copyright (c) 2022 Pawel Þorkelsson
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in all
-- copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-- SOFTWARE.
--:: SHORTHANDS ::--
local floor, insert, remove, f = math.floor, table.insert, table.remove, string.format
--:: LOCAL FUNCTUONS ::--
-- Returns true if 2 rectangles are intersecting
local function rect(x1,y1,w1,h1, x2,y2,w2,h2)
return x1 < x2+w2 and x2 < x1+w1 and y1 < y2+h2 and y2 < y1+h1
end
-- Returns true of table "tab" contains item "item"
local function contains(tab, item)
for k,v in pairs(tab) do
if v == item then
return true, k
end
end
return false
end
local spatial = {
filters = {
default = function() return true end,
rect = function(item, x, y, width, height)
return rect(item.x, item.y, item.width, item.height, x, y, width, height)
end
}
}
local mt = {__index = spatial}
setmetatable(spatial, mt)
-- Making the module callable
function mt.__call(self, ...)
return self.new(...)
end
--:: INTERNAL METHODS ::--
--- Returns cell coordinates for every cells a rectangle intersects with
function spatial:getCellCoordinates(x, y, width, height)
-- Finding the min and max cell that intersects
local minX, maxX = floor(x / self.cellSize), floor((x + width) / self.cellSize)
local minY, maxY = floor(y / self.cellSize), floor((y + height) / self.cellSize)
-- Gathering coordinates
local cells = {}
for i=minY, maxY do
for j=minX, maxX do
insert(cells, {x = j, y = i})
end
end
return cells
end
-- Returns all cells a rectangle intersects with. Skips non existing cells.
function spatial:getCells(x, y, width, height)
local cellCoordinates = self:getCellCoordinates(x, y, width, height)
local cells = {}
for i,v in ipairs(cellCoordinates) do
if self.grid[v.y] then
if self.grid[v.y][v.x] then
insert(cells, self.grid[v.y][v.x])
end
end
end
return cells
end
-- Inserts "item" into the cell at cellX x cellY
-- Also creates the cell if it does not exist and checks for duplicates
-- Returns false in case of a dubplicate.
function spatial:addToCell(item, cellX, cellY)
-- Making sure the cell exists
self.grid[cellY] = self.grid[cellY] or {}
self.grid[cellY][cellX] = self.grid[cellY][cellX] or {_CELL = {x = cellX, y = cellY}}
-- Checking for dubplicates
if contains(self.grid[cellY][cellX], item) then return false end
--Inserting
insert(self.grid[cellY][cellX], item)
insert(item._SPATIAL.cells, self.grid[cellY][cellX])
self.totalLength = self.totalLength + 1
end
-- Iterates over every item in every cell
function spatial:forEach(func)
for y, col in pairs(self.grid) do
for x, cell in pairs(col) do
for index, item in pairs(cell) do
func(item, self.grid[y][x], index)
end
end
end
end
-- Makes sure a given filter exists.
function spatial:validateFilter(filter)
filter = filter or "default"
if type(filter) == "string" then
assert(self.filters[filter], f("Invalid filter '%s'", filter))
filter = self.filters[filter]
elseif type(filter) == "function" then
filter = filter
else
error(f("Invalid filter '%s'", tostring(filter)))
end
return filter
end
--:: PUBLIC METHODS ::--
-- Creates and returns a new instance
function spatial.new(cellSize)
return setmetatable({
cellSize = cellSize or 64,
grid = {},
length = 0, -- Number of items, not counting duplicates
totalLength = 0 -- Total number of items, Including duplicates
}, mt)
end
-- Adds a custom filter to the filters table
function spatial.newFilter(name, func)
spatial.filters[name] = func
end
-- Inserts an item into the grid.
function spatial:insert(item, x, y, width, height)
-- Getting cells
local cells = self:getCellCoordinates(x, y, width or 1, height or 1)
-- A _SPATIAL table is added to the item with useful stuff
item._SPATIAL = {
cells = {}, -- The cells the item lives in
spatial = self
}
-- Inserting item into appropriate cells
for i,v in ipairs(cells) do
self:addToCell(item, v.x, v.y)
end
self.length = self.length + 1
return item
end
-- Removes an item from the grid
function spatial:remove(item)
local removed = false
if item._SPATIAL then
for _,cell in ipairs(item._SPATIAL.cells) do
local exists, key = contains(cell, item)
if exists then
remove(cell, key)
removed = true
self.totalLength = self.totalLength - 1
end
end
end
if removed then
self.length = self.length - 1
return true
end
end
-- Updates an items position on the grid.
function spatial:update(item, x, y, width, height)
self:remove(item)
self:insert(item, x, y, width, height)
end
--:: QUERY FUNCTIONS ::--
-- General query function. Returns every item that passes the filter
-- Unlike queryRect/queryPoint, This function has to iterate over every single item in the hash.
-- This can be slow if you have a large quantity of items in there.
function spatial:query(filter)
filter = self:validateFilter(filter)
local items, len = {}, 0
self:forEach(function(item, x, y, i)
if filter(item) then
if not contains(items, item) then
insert(items, item)
len = len + 1
end
end
end)
return items, len
end
--- Returns all the items in a rectangle
function spatial:queryRect(x, y, width, height, filter)
filter = self:validateFilter(filter)
local cells = self:getCells(x, y, width, height)
local items, len = {}, 0
for i,v in ipairs(cells) do
for _, item in ipairs(v) do -- Looping through items
if not contains(items, item) then -- Checking for duplicates
if filter(item, x, y, width, height) then -- Checking if filter passes
insert(items, item)
len = len + 1
end
end
end
end
return items, len
end
-- Returns all items in a point
function spatial:queryPoint(x, y, filter)
return self:queryRect(x, y, 1, 1, filter)
end
return spatial