How to create trajectory (Same as in angry bird) for archery game?

Sarthak · August 2014

Hi,

I have created basic archery game, but now i want to display trajectory based on drag distance (which same as angry bird), so please help me or suggest me how can i get it ?
Give me some guidance , how do i achieve this?

I have seen below post ,
http://giderosmobile.com/forum/discussion/2130/drawing-a-direction-path/p1
but i am not able to get it. So please help me.

Thank you.

hgvyas123 · August 2014

Try this code

--[[
 
This code is MIT licensed, see <a href="http://www.opensource.org/licenses/mit-license.php" rel="nofollow">http://www.opensource.org/licenses/mit-license.php</a>
(C) 2010 - 2011 Gideros Mobile 
 
]]
 
require "box2d"
 
b2.setScale(30)
 
-- this table holds the dynamic bodies and their sprites
local actors = {}
 
-- create world
local world = b2.World.new(0, 9.8)
 
local DummyWorld = b2.World.new(0, 9.8)
 
-- create ground bitmap and add to stage
local groundBitmap = Bitmap.new(Texture.new("ground.png"))
groundBitmap:setAnchorPoint(0, 1)
groundBitmap:setY(320)
stage:addChild(groundBitmap)
 
-- create ground body
local ground = world:createBody({})
 
-- ground body is consists of 24 tiny edges
local shape = b2.EdgeShape.new()
local groundFilter = {categoryBits = 1, maskBits = 6}
for x=0,460,20 do
	local x1 = x
	local x2 = x + 20
	local y1 = math.cos((x1 - 240) * 0.01) * 80 + 240
	local y2 = math.cos((x2 - 240) * 0.01) * 80 + 240
 
	shape:set(x1, y1, x2, y2)
	ground:createFixture({shape = shape, density = 0, filter})
end
 
-- create a circle body with given texture and collision filter and add it to stage
 
local function onTouchDown(self,event)
 
		self.isFocus = true
		self.startX = event.x
		self.startY = event.y
 
end
 
local xPosArr = {}
local yPosArr = {}
local myCircles = {}
 
function drawArc(xc,yc,xradius,yradius,startAngle,endAngle,isFill)
	if yradius == nil then
		yradius = xradius
	end
	if startAngle == nil then
		startAngle = 0
	end
	if endAngle == nil then
		endAngle = 360
	end
	if isFill == nil then
		isFill = true
	end
	local shape = Shape.new()
	if isFill then
		shape:setFillStyle(Shape.SOLID, 0x000000, 0.5)
	else
		shape:setLineStyle(3, 0x000000)
	end
	shape:beginPath()
	for i=startAngle,endAngle do
		if i==1 then
			shape:moveTo(math.sin(math.rad(i)) * xradius, math.cos(math.rad(i)) * yradius)
		else
			shape:lineTo(math.sin(math.rad(i)) * xradius, math.cos(math.rad(i)) * yradius)
		end
	end
	if isFill then
		shape:closePath()
	end
	shape:endPath()
	shape:setPosition(xc,yc)
	return shape
end
 
for i=1,40 do
	myCircles[i] = drawArc(-100,100,2,2)
	stage:addChild(myCircles[i])
end
local function onTouchMove(self,event)
	if self.isFocus then
		print("called")
		local body = DummyWorld:createBody{type = b2.DYNAMIC_BODY, position = {x = stage.sprite:getX(), y = stage.sprite:getY()}}
 
		local shape = b2.CircleShape.new(0, 0, 12)
		body:createFixture{shape = shape, density = 1, restitution = 0.2, friction = 0.1}
 
		local xVect = (self.startX-event.x)*0.07
        local yVect = (self.startY-event.y)*0.07
        --applye impulse to target
        body:applyLinearImpulse(xVect, yVect, body:getPosition())
 
		for i=1,40 do
			DummyWorld:step(1/60, 8, 3)
			local x,y = body:getPosition()
 
 
			myCircles[i]:setPosition(x,y)
		end
 
		DummyWorld:destroyBody(body)
	end
end
 
local function onTouchUp(self,event)
	if self.isFocus then
		self.isFocus = false
		for i=1,40 do
			myCircles[i]:setPosition(-100,100)
		end
		local body = world:createBody{type = b2.DYNAMIC_BODY, position = {x = stage.sprite:getX(), y = stage.sprite:getY()}}
 
		local shape = b2.CircleShape.new(0, 0, 12)
		body:createFixture{shape = shape, density = 1, restitution = 0.2, friction = 0.1}
		stage.sprite.body = body
		actors[body] = stage.sprite
		 local xVect = (self.startX-event.x)*0.07
        local yVect = (self.startY-event.y)*0.07
        --applye impulse to target
        body:applyLinearImpulse(xVect, yVect, body:getPosition())
	end
end
 
local function createCircle(texture, x, y, filter)
	--local body = world:createBody{type = b2.KINEMATIK_BODY, position = {x = x, y = y}}
 
	--local shape = b2.CircleShape.new(0, 0, 12)
	--body:createFixture{shape = shape, density = 1, restitution = 0.2, friction = 0.1}
 
	local sprite = Bitmap.new(Texture.new(texture, true))
	sprite:setPosition(240,210)
	sprite:setScale(0.5,0.5)
	sprite:setAnchorPoint(0.5, 0.5)
	stage:addChild(sprite)
 
 
	stage.sprite = sprite
	--actors[body] = sprite
end
 
-- create circles
 
 
createCircle("blue-circle.png", 240, 160, blueFilter)
 
local body = world:createBody{type = b2.DYNAMIC_BODY, position = {x = 100, y = 90}}
 
local shape = b2.CircleShape.new(0, 0, 12)
body:createFixture{shape = shape, density = 1, restitution = 0.2, friction = 0.1}
 
local sprite = Bitmap.new(Texture.new("blue-circle.png", true))
sprite:setPosition(240,210)
sprite:setScale(0.5,0.5)
sprite:setAnchorPoint(0.5, 0.5)
stage:addChild(sprite)
 
actors[body] = sprite
 
-- step the world and then update the position and rotation of sprites
local function onEnterFrame()
	world:step(1/60, 8, 3)
 
	for body,sprite in pairs(actors) do
		sprite:setPosition(body:getPosition())
		sprite:setRotation(body:getAngle() * 180 / math.pi)
	end
end
 
stage:addEventListener(Event.ENTER_FRAME, onEnterFrame)
 
stage:addEventListener(Event.MOUSE_DOWN,onTouchDown,stage)
	stage:addEventListener(Event.MOUSE_MOVE,onTouchMove,stage)
	stage:addEventListener(Event.MOUSE_UP,onTouchUp,stage)
 
local debugDraw = b2.DebugDraw.new()
world:setDebugDraw(debugDraw)
stage:addChild(debugDraw)

ar2rsawseen · August 2014

Yep, its that simple

Sarthak · August 2014

Thank you.

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