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opus/sys/apis/jumper/core/path.lua
kepler155c@gmail.com 1b9450017d refactor + cleanup
2017-10-27 20:24:48 -04:00

67 lines
2.0 KiB
Lua

--- The Path class.
-- The `path` class is a structure which represents a path (ordered set of nodes) from a start location to a goal.
-- An instance from this class would be a result of a request addressed to `Pathfinder:getPath`.
--
-- This module is internally used by the library on purpose.
-- It should normally not be used explicitely, yet it remains fully accessible.
--
if (...) then
local t_remove = table.remove
local Path = {}
Path.__index = Path
function Path:new()
return setmetatable({_nodes = {}}, Path)
end
--- Iterates on each single `node` along a `path`. At each step of iteration,
-- returns the `node` plus a count value. Aliased as @{Path:nodes}
-- @usage
-- for node, count in p:iter() do
-- ...
-- end
function Path:nodes()
local i = 1
return function()
if self._nodes[i] then
i = i+1
return self._nodes[i-1],i-1
end
end
end
--- `Path` compression modifier. Given a `path`, eliminates useless nodes to return a lighter `path`
-- consisting of straight moves. Does the opposite of @{Path:fill}
-- @class function
-- @treturn path self (the calling `path` itself, can be chained)
-- @see Path:fill
-- @usage p:filter()
function Path:filter()
local i = 2
local xi,yi,zi,dx,dy,dz, olddx, olddy, olddz
xi,yi,zi = self._nodes[i].x, self._nodes[i].y, self._nodes[i].z
dx, dy,dz = xi - self._nodes[i-1].x, yi-self._nodes[i-1].y, zi-self._nodes[i-1].z
while true do
olddx, olddy, olddz = dx, dy, dz
if self._nodes[i+1] then
i = i+1
xi, yi, zi = self._nodes[i].x, self._nodes[i].y, self._nodes[i].z
dx, dy, dz = xi - self._nodes[i-1].x, yi - self._nodes[i-1].y, zi - self._nodes[i-1].z
if olddx == dx and olddy == dy and olddz == dz then
t_remove(self._nodes, i-1)
i = i - 1
end
else break end
end
return self
end
return setmetatable(Path,
{__call = function(_,...)
return Path:new(...)
end
})
end