Box2d 1 dimensional wall

Zizanyman

I am using box2d for physics in my game and I came across a problem. In the game , I want to generate a wall in a random position on the screen. Then, you will have to draw a line as close to that wall as possible. The problem is, if I randomly generated coordinates for the wall, it wouldn't be flat. I want to generate a flat wall in a random position on the screen. Is there any way to do this?

HubertRonald

Hi @Zizanyman

@H4ch1 gave us a "doodle jump clone" and although there are not a random walls if there are random floors.

You can take some ideas of this script
http://giderosmobile.com/forum/discussion/473/let039s-jump-d#Item_10

I hope this script can help you

ar2rsawseen

@Zizanyman for the wall, you don't need to randomly generate coordinates.
You only need to randomly generate 1 center coordinate, and then dimensions (width and height) and rotation, so that way you can always have a flat random wall

Zizanyman

Thanks @ar2rsawseen! That worked to make it flat, but it generates the same coordinates every time. On the init function, this is my code to put it in a random spot.

self:wall(realx,realy) -- realx and realy are the random coordinates

And my code when I am creating the wall object:

wall:beginPath()
wall:moveTo(-screenW/2,-screenH/2)
wall:lineTo(screenW/2, -screenH/2)
wall:closePath()
wall:endPath()
wall:setPosition(x,y)

ar2rsawseen

@Zizanyman do you mean it gets same coordinates all the time, or only on app start?

Zizanyman

The wall is in the same place every time.

ar2rsawseen

@Zizanyman can you post the full self:wall function

Zizanyman

@ar2rsawseen This is the self:wall function (I am basing my code after the box2d accelerometer post on app coding easy if this looks familiar):

function scene:wall(x, y, width, height)
local wall = Shape.new()
wall:beginPath()

wall:moveTo(-screenW/2,-screenH/2)
wall:lineTo(screenW/2, -screenH/2)
wall:closePath()
wall:endPath()
wall:setPosition(x,y)

local body = self.world:createBody{type = b2.STATIC_BODY}
body:setPosition(wall:getX(), wall:getY())
body:setAngle(wall:getRotation() * math.pi/180)
local poly = b2.PolygonShape.new()
poly:setAsBox(wall:getWidth()/2, wall:getHeight()/2)
local fixture = body:createFixture{shape = poly, density = 1.0,
friction = 10, restitution = 0.2}
wall.body = body
wall.body.type = "wall"
self.isVisible = false

self:addChild(wall)

return wall
end

And then as I said earlier I used self:wall(realx, realy) in the init function to set the random coordinates (realx and realy are random values).

My complete code so far is attached if you want to take a look( I know your really busy, though)

ar2rsawseen

From your project I see that you generate realx and realy only once, you should rengenerate them, before creating new wall, so it would be in different position.
Placing them inside function scene:init() will help achieving new position on each scene change

Zizanyman

@ar2sawseen I tried doing this, and it still made the same coordinates the same time. I know it is just the random values (realx and realy) that are causing my troubles because I put print(realx) and print(realy) into my code, and it prints out the same numbers every time, 92 and 647. I am going to start a new discussion (question called random values not working) instead of continuing on this one, because now I know what the problem is, and a new discussion will point out this problem.