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165 lines
4.6 KiB
ReStructuredText
165 lines
4.6 KiB
ReStructuredText
HC.spatialhash
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==============
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::
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spatialhash = require 'HC.spatialhash'
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A spatial hash implementation that supports scenes of arbitrary size. The hash
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is sparse, which means that cells will only be created when needed.
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.. class:: Spatialhash([cellsize = 100])
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:param number cellsize: Width and height of a cell (optional).
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Create a new spatial hash with a given cell size.
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Choosing a good cell size depends on your application. To get a decent speedup,
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the average cell should not contain too many objects, nor should a single
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object occupy too many cells. A good rule of thumb is to choose the cell size
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so that the average object will occupy only one cell.
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.. note::
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The syntax depends on used class system. The shown syntax works when using
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the bundled `hump.class <http://vrld.github.com/hump/#hump.class>`_ or
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`slither <https://bitbucket.org/bartbes/slither>`_.
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**Example**::
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Spatialhash = require 'hardoncollider.spatialhash'
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hash = Spatialhash(150)
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.. function:: Spatialhash:cellCoords(x,y)
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:param numbers x, y: The position to query.
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:returns: Coordinates of the cell which would contain ``x,y``.
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Get coordinates of a given value, i.e. the cell index in which a given point
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would be placed.
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**Example**::
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local mx,my = love.mouse.getPosition()
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cx, cy = hash:cellCoords(mx, my)
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.. function:: Spatialhash:cell(i,k)
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:param numbers i, k: The cell index.
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:returns: Set of objects contained in the cell.
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Get the cell with given coordinates.
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A cell is a table which's keys and value are the objects stored in the cell,
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i.e.::
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cell = {
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[obj1] = obj1,
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[obj2] = obj2,
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...
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}
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You can iterate over the objects in a cell using ``pairs()``::
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for object in pairs(cell) do stuff(object) end
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**Example**::
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local mx,my = love.mouse.getPosition()
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cx, cy = hash:cellCoords(mx, my)
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cell = hash:cell(cx, cy)
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.. function:: Spatialhash:cellAt(x,y)
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:param numbers x, y: The position to query.
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:returns: Set of objects contained in the cell.
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Get the cell that contains point x,y.
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Same as ``hash:cell(hash:cellCoords(x,y))``
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**Example**::
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local mx,my = love.mouse.getPosition()
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cell = hash:cellAt(mx, my)
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.. function:: Spatialhash:shapes()
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:returns: Set of all shapes in the hash.
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Get *all* shapes that are recorded in the hash.
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.. function:: Spatialhash:inSameCells(x1,y1, x2,y2)
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:param numbers x1,y1: Upper left corner of the query bounding box.
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:param numbers x2,y2: Lower right corner of the query bounding box.
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:returns: Set of all shapes in the same cell as the bbox.
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Get the shapes that are in the same cell as the defined bounding box.
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.. function:: Spatialhash:register(obj, x1,y1, x2,y2)
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:param mixed obj: Object to place in the hash. It can be of any type except `nil`.
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:param numbers x1,y1: Upper left corner of the bounding box.
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:param numbers x2,y2: Lower right corner of the bounding box.
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Insert an object into the hash using a given bounding box.
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**Example**::
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hash:register(shape, shape:bbox())
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.. function:: Spatialhash:remove(obj[, x1,y1[, x2,y2]])
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:param mixed obj: The object to delete
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:param numbers x1,y1: Upper left corner of the bounding box (optional).
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:param numbers x2,y2: Lower right corner of the bounding box (optional).
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Remove an object from the hash using a bounding box.
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If no bounding box is given, search the whole hash to delete the object.
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**Example**::
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hash:remove(shape, shape:bbox())
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hash:remove(object_with_unknown_position)
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.. function:: Spatialhash:update(obj, x1,y1, x2,y2, x3,y3, x4,y4)
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:param mixed obj: The object to be updated.
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:param numbers x1,y1: Upper left corner of the bounding box before the object was moved.
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:param numbers x2,y2: Lower right corner of the bounding box before the object was moved.
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:param numbers x3,y3: Upper left corner of the bounding box after the object was moved.
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:param numbers x4,y4: Lower right corner of the bounding box after the object was moved.
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Update an objects position given the old bounding box and the new bounding box.
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**Example**::
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hash:update(shape, -100,-30, 0,60, -100,-70, 0,20)
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.. function:: Spatialhash:draw(draw_mode[, show_empty = true[, print_key = false]])
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:param string draw_mode: Either 'fill' or 'line'. See the LÖVE wiki.
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:param boolean show_empty: Wether to draw empty cells (optional).
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:param boolean print_key: Wether to print cell coordinates (optional).
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Draw hash cells on the screen, mostly for debug purposes
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**Example**::
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love.graphics.setColor(160,140,100,100)
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hash:draw('line', true, true)
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hash:draw('fill', false)
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