dcearth/nodes.lua

--Manage the pathfinding nodes used by DEFCON.
--This is important for a mapping tool because the DEFCON client will not load a map unless
--the pathfinding nodes form a connected graph.
local t = {}
local bmp = require 'bmp'
local lg = assert( love.graphics )

local isSailable

local function isConnected( startNode, endNode )
  local ix, iy, fx, fy = startNode.x, startNode.y, endNode.x, endNode.y
  if fx < -180 then fx = fx + 180 end
  if fx > 180 then fx = fx - 180 end
  
  local dx, dy = fx - ix, fy - iy
  local mag = math.sqrt( dx * dx + dy * dy )
  local n = 2 * math.floor( mag )
  dx, dy = 0.5 * dx / mag, 0.5 * dy / mag
  
  for i = 1, n do
    ix, iy = ix + dx, iy + dy
    if not( isSailable( ix, iy ) ) then return nil end
  end
  
  return true
end

function t.getClosest( nodes, x, y )
  local d = math.huge
  local closestNode
  for _, node in pairs( nodes.nodes ) do
    local nx, ny = node.x, node.y
    local nd = (nx - x) * (nx - x) + (ny - y) * (ny - y)
    if nd < d then d = nd; closestNode = node end
  end
  return closestNode
end

function t.load( filename, sailable )
  
  isSailable = sailable
  local img, imgd = bmp.load( filename )
  local nodes = { visible = true, nodes = {}, points = {}, connections = {}, img = img }
  
  print( "=== Loading Nodes: ===" )
  local n = 1
  for x = 0, 799 do
    for y = 0, 399 do
      if imgd:getPixel( x, 399 - y ) > 0 then
        local long = 360 * ( x - 800 ) / 800 - 360 / 2 + 360
        local lat = 360 * ( 600 / 800 ) * ( 600 - y ) / 600 - 180
        nodes.nodes[n] = {x = long, y = lat}
        nodes.points[ 2 * n - 1 ] = long
        nodes.points[ 2 * n ] = lat
        print( n, long, lat )
        n = n + 1
      end
    end
  end
  
  for i, srcNode in ipairs( nodes.nodes ) do
    local adjacent = {}
    
    for j, destNode in ipairs( nodes.nodes ) do
      adjacent[j] = isConnected( srcNode, destNode )
    end
    
    nodes.connections[i] = adjacent
  end
  
  print( "=== Nodes Loaded ===" )
  return setmetatable( nodes, {__index = t } )
end

--Determine if graph has more than one connected component.
function t.isConnected( nodes )
  
end

function t.draw( nodes )
  lg.setPointSize( 10 )
  lg.setColor( 1, 1, 1, 0.5 )
  lg.points( nodes.points )
  
  for i, connection in pairs( nodes.connections ) do
    for j in pairs( connection ) do
      local ix, iy, fx, fy = nodes.nodes[i].x, nodes.nodes[i].y, nodes.nodes[j].x, nodes.nodes[j].y
      lg.line( ix, iy, fx, fy )
    end
  end
end

function t.drawConnections( nodes )
  
end

function t.save( nodes, filename )
  
end

return t