Corona SDK - bezier curve exemple

bezier.lua

-------------------------------------------------
-- bezier.lua
-- Version: 1.0
-- Author: Rajendra Pondel
-- Email: neostar20@gmail.com
 
-- Copyright: 2012 Rajendra Pondel <neostar20@gmail.com>
 
-- 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.
 
 
local bezier = {}
 
function bezier:curve(xv, yv)
        local reductor = {__index = function(self, ind)
                return setmetatable({tree = self, level = ind}, {__index = function(curves, ind)
                        return function(t)
                                local x1, y1 = curves.tree[curves.level-1][ind](t)
                                local x2, y2 = curves.tree[curves.level-1][ind+1](t)
                                return x1 + (x2 - x1) * t, y1 + (y2 - y1) * t
                                end
                        end})
                end
        }
        local points = {}
        for i = 1, #xv do
                        points[i] = function(t) return xv[i], yv[i] end
        end
        return setmetatable({points}, reductor)[#points][1]
end
 
return bezier

main.lua

local bg = display.newImage("bg_earth.jpg")
bg.x = 964/2
bg.y = 507
 
local ship = display.newImage("ship03.png")
ship.x = 500
ship.y = 200
ship.name = "ship"
 
-- understood proprierties of bezier curve
--local curve = bezier:curve({xInitial, xControlPoint1, xControlPoint2, xControlPoint3}, {yInitial, yControlPoint1, yControlPoint2, yControlPoint3})

local bezier = require('bezier') 
local curve =  bezier:curve({350, 1100, 350},{ 1080, 686, 500})
local x1, y1 = curve(10.51)
local line3 = display.newLine(x1, y1, x1+1, y1+1)
line3:setColor(0, 0, 255, 255 )
-- imput 0 (zero) value in line below for don´t see the line
line3.width = 3
 
for i=0.02, 1.01, 0.01 do
  local x, y = curve(i)
  line3:append(x, y)
  print(i, x, y)
end
 
-- move ship along curve
local pointInc = 0.00
 
local function follow (event )
  if pointInc < 1.01 then
        ship.x, ship.y = curve(pointInc)
        --print(pointInc,ship.x, ship.y)
        pointInc = pointInc + 0.01
     else
         Runtime:removeEventListener("enterFrame",follow)
     end
end
 
Runtime:addEventListener("enterFrame",follow);