Emanuele Feronato

Talking about String Avoider game, Game development and iOS.

As you know, Stringy game was built starting from this prototype: Develop a Flash game like String Avoider – AS3 version – and more!.

Christian Wisniewski made a Corona version of the prototype to be played on mobile devices as you can see here:

With this main.lua file:

-- Declaring Variables
-- Stage Width and Height
local _W,_H = display.contentWidth,display.contentHeight

local tailLength = 5
local tailNodes = 200
local head = display.newCircle(_W/2,_H/2,10)
local nodes = {}

for i=1,tailNodes,1 do
	nodes[i] = {}
	nodes[i].x = head.x
	nodes[i].y = head.y
end

-- Creating Display Groups
local tailGroup = display.newGroup()

local function startDrag(event)
	-- Store the Target (the Head) in a variable
	local t = event.target
	if event.phase == "began" then
		-- When the touch started, set the Focus on the Head
		display.getCurrentStage():setFocus( t )
		t.isFocus = true
		-- Store initial Position of the Head
		t.x0 = event.x - t.x
        	t.y0 = event.y - t.y
	elseif t.isFocus then
		if event.phase == "moved" then
			-- While moving the head
			-- remove every drawn line from the group
			for i=tailGroup.numChildren,1,-1 do
				tailGroup:remove(i)
			end
			
			-- Move the Head
			t.x = event.x - t.x0
			t.y = event.y - t.y0
			
			-- Create starting line and insert it into the group
			local line = display.newLine(head.x,head.y,nodes[1].x,nodes[1].y)
			tailGroup:insert(line)
			line.width = 20
			
			nodes[1].x = head.x
			nodes[1].y = head.y
			
			-- Loop through every tailNode and save new positions in table
			-- Note: LUA tables start with an index of 1 and not 0!
			for i=2,tailNodes,1 do
				local nodeAngle = math.atan2(nodes[i].y-nodes[i-1].y,nodes[i].x-nodes[i-1].x);
				nodes[i].x = nodes[i-1].x+tailLength*math.cos(nodeAngle)
				nodes[i].y = nodes[i-1].y+tailLength*math.sin(nodeAngle)
				
				-- You could use
				-- line:append(nodes[i].x,nodes[i].y)
				-- but this wouldn't allow you to alter each segment (fading the color, reducing linewidth etc.)
				
				-- Creating new line segments
				local nLine = display.newLine(nodes[i-1].x,nodes[i-1].y,nodes[i].x,nodes[i].y)
				-- c will store the colorvalue - starting from 255 and ending with 0 (white to black)
				local c = 255-i/tailNodes*255
				nLine:setColor(c)
				-- width will start at 20 and fade out to 0
				nLine.width = line.width-i/tailNodes*line.width
				
				-- Important: insert the new Line segments into the table!
				tailGroup:insert(nLine)
			end
		elseif event.phase == "ended" or event.phase == "cancelled" then
			-- Remove the focus
			display.getCurrentStage():setFocus( t, nil )
			t.isFocus = false
		end
	end
end

-- Create touch Eventlistener
head:addEventListener("touch",startDrag)

During next days I will improve the prototype, maybe this could be a start for a mobile version of Stringy game.