Help with Code

tyguy2 · August 11, 2013, 7:06pm

Hello, I am new (everyone says it but I am saying it anyway. Deal with it )

I am writing a code that involves objects hitting each other. I looked through different discussions, but all of them were too complex and was too specific for my taste.

My question is:
What is a simple code that could detect when 2 objects are touching?

(If you need to look at the code, just ask. Just a reminder though, the code is simple!)

dave1707 · August 11, 2013, 7:23pm


  -- all of this info can be found in the online manual
  -- see the physics tab

function setup() 
    -- creates a circle that doesn't move
    c1 = physics.body(CIRCLE,100)    -- create body for 1st circle
    c1.type=STATIC -- static means the circle doesn't move
    c1.x=WIDTH/2 -- starting x,y values
    c1.y=300
    
    -- creates a circle that is influenced by gravity
    c2 = physics.body(CIRCLE,50)    -- create body for 2nd circle
    c2.x=WIDTH/2  -- starting x,y values
    c2.y=800
    c2.restitution=1  -- how much the circle bounces when collided
end

function draw()
    background(40,40,50)
    stroke(255)
    strokeWidth(1)
    noFill()
    ellipse(c1.x,c1.y,200,200)    -- draw the 1st circle position
    ellipse(c2.x,c2.y,100,100)    -- draw the 2nd circle position   
end

function collide(c)
    if c.state==BEGAN then  -- do this when the collision begins
        print("\
collision")
        print(c.id)
        print("radius of body A ",c.bodyA.radius)
        print("radius of body B ",c.bodyB.radius)
        print("position of body A ",c.bodyA.x)
        print("position of body A ",c.bodyA.y)
        -- see physics.contact and physics.body in the reference manual
        -- for other info that's available during a collision
    end  
end

SteveNoob · August 11, 2013, 8:11pm

Dave is a coding machine!!

tyguy2 · August 11, 2013, 8:23pm

Could you please explain the upper part of the code?

dave1707 · August 11, 2013, 8:41pm

See the comments added to the above code.

tyguy2 · August 11, 2013, 9:09pm

Thank you!!!

tyguy2 · August 11, 2013, 10:07pm

After reviewing the code more in depth, I found that this code doesn’t work for the program that I am creating.

All I need to do is have an object not go through another object. Then I need it to return to a certain position. Can you do this?

dave1707 · August 12, 2013, 8:11am

@tyguy2 Can you be a little more specific. Do you want the first object to collide with another object, then return back to it’s original starting point. Does the second object move randomly on the screen. I’m sure whatever you want to happen can be done, but I want to keep it simple so you can expand on the code.

tyguy2 · August 12, 2013, 6:11pm

Here is an example of what I want to do:

An object starts at point A. It begins to move upwards and runs into an object at point B. It then returns to point A.

Here is a visual version:

      Point B-->  ____
                          ^
                          ^
                          ^
                          ^  
     Point A-->  ____   <-- Returns here

JakAttak · August 12, 2013, 6:33pm

@tyguy2, do you want it to jump back to point A, or smoothly move back there

dave1707 · August 12, 2013, 6:42pm

There are going to be many ways of doing this. The correct way will depend on what else you want to happen.


displayMode(FULLSCREEN)

function setup()
    val=1    -- value and direction to move c1
    start=vec2(500,100)    -- starting position of c1
    
    c1=physics.body(CIRCLE,50)    --create circle c1
    c1.x=start.x
    c1.y=start.y
    c1.gravityScale=0
    
    c2=physics.body(CIRCLE,50)    -- create circle c2
    c2.x=100
    c2.y=600  
    c2.gravityScale=0  
end

function draw()
    background(40, 40, 50)
    fill(255)
    ellipse(c1.x,c1.y,100)    -- draw circle c1
    ellipse(c2.x,c2.y,100)    -- draw circle c2
    c1.y=c1.y+val    -- move c1 up or down the screen
    c2.x=c2.x+1    -- move c2 across the screen
    if c1.y<=start.y then -- c1 back at starting position
        val=1        -- set value to move c1 up the screen
        c2.x=100     -- reset c2 back to it starting position
        c2.y=600
    end
end

function collide(c)
    if c.state==BEGAN then    -- check for collision
        val=-1    -- reverse direction
    end  
end

JakAttak · August 12, 2013, 6:48pm

Edit: Just realized @dave1707s way showcases both the methods I mentioned above

tyguy2 · August 12, 2013, 8:37pm

Here, this isn’t working. I’ll send the code I have currently:

--main--
function setup()
parameter.integer("Speed", 1, 100, 6)
parameter.integer("Gravity",1, 100, 5) -- Not really "gravity." Just a force you work against
Tower= Tower() -- "point b" goal
Runner= Runner()-- player
    spx = 100 
    spy = 100
    watchstuff()
end

function draw()
background(0,0,0)
sprite("Documents:background", 400, 100, 2000,2000)

spy = spy - Gravity
Tower: draw() 
Runner: draw() 
sprite("Documents:yellow", 300, 800, 2000, 5)
end
    
function touched (touch)     
 spy = spy + Speed
end

function watchstuff()
    parameter.watch("spx"). --To watch where runner is
    parameter.watch("spy")
    end

--Tower--

Tower = class()

function Tower:init(x)
    
    self.x = x
end

function Tower:draw()
    sprite("Documents:Tower", 400,900, 1024/2,768/2)
end

function Tower:touched(touch)
   
end

--Runner--

Runner = class()

function Runner:init(x)
  
    self.x = x
end

function Runner:draw()
    sprite("Documents:Runner", 400, spy, 768/8,1024/8)
end

function Runner:touched(touch)
    
end

I want the runner to move to point b and instantly move back to point A( beginning location).

JakAttak · August 12, 2013, 9:17pm

@tyguy2 I believe this does what you want,
I pointed out changes with comments

Most notably I changed the positions and sizes of tower and runner to be self.variables, and changed spx and spy to be runner.x and runner.y

Also, I changed the sprites so that I could see what was happening, you’ll need to change them back

--# Main
function setup()
    parameter.integer("Speed", 1, 100, 6)
    parameter.integer("force",1, 100, 5) -- Just a force you work against
    tower = Tower(400,900) -- "point b" goal
    runner = Runner(400, 100)-- player
    parameter.watch("runner.x") -- change
    parameter.watch("runner.y") -- change
end

function draw()
    background(0,0,0)
    sprite("SpaceCute:Background", 400, 100, 2000,2000)

    runner.y = runner.y - force -- change
    tower:draw() 
    runner:draw() 
    sprite("Planet Cute:Grass Block", 300, 800, 2000, 5)
end

function touched(touch)
    runner.y = runner.y + Speed -- change
end

--Tower--

Tower = class()

function Tower:init(x, y)
    self.x = x -- set position
    self.y = y
    self.width = WIDTH/2 -- set size
    self.height = HEIGHT/2
end

function Tower:draw()
    sprite("Small World:Church", self.x,self.y, self.width,self.height)
end

function Tower:touched(touch)

end

--Runner--

Runner = class()

function Runner:init(x, y)
    self.x = x -- set position
    self.y = y
    self.initialY = y -- set starting position as variable
end

function Runner:draw()
    if self.y >= tower.y - tower.height/2 then -- if reached tower
        self.y = self.initialY -- set position back to starting position
    end
    sprite("Planet Cute:Character Boy", self.x, self.y, HEIGHT/8,WIDTH/8) -- change
end

function Runner:touched(touch)

end

tyguy2 · August 13, 2013, 9:41am

Thank you. I will test this later tonight.

tyguy2 · August 13, 2013, 6:21pm

2 things and this code works flawlessly.

1.) Everything is smushed. I am trying to fix it as we speak. If you can help, the runner’s dimensions are as follows:

768 * 1024

The tower’s are:

1024 * 768

2.) When the runner returns to point A, is it possible to put something down for him to “stand” on. I continually have to problem of him falling of screen.

Thank you so much for the help!

JakAttak · August 13, 2013, 7:31pm

You can change the dimensions to fit your needs, they are in the individual classes

If you still can’t figure it out let me know and I’ll show you exactly where

The runner falls of the screen because of the force.

If you want him to not fall off the screen, do something like this

runner.y = math.max(runner.y, 0)

JakAttak · August 13, 2013, 7:32pm

Here is some code that incorporates this:

function setup()
    parameter.integer("Speed", 1, 100, 6)
    parameter.integer("force",1, 100, 5) -- Just a force you work against
    tower = Tower(400,900) -- "point b" goal
    runner = Runner(400, 100)-- player
    parameter.watch("runner.x") -- change
    parameter.watch("runner.y") -- change
end

function draw()
    background(0,0,0)
    sprite("SpaceCute:Background", 400, 100, 2000,2000)

    runner.y = runner.y - force -- change
    runner.y = math.max(runner.y, runner.height/2)
    tower:draw() 
    runner:draw() 
    sprite("Planet Cute:Grass Block", 300, 800, 2000, 5)
end

function touched(touch)
    runner.y = runner.y + Speed -- change
end

--Tower--

Tower = class()

function Tower:init(x, y)
    self.x = x -- set position
    self.y = y
    self.width = WIDTH/2 -- set size
    self.height = HEIGHT/2
end

function Tower:draw()
    sprite("Small World:Church", self.x,self.y, self.width,self.height)
end

function Tower:touched(touch)

end

--Runner--

Runner = class()

function Runner:init(x, y)
    self.x = x -- set position
    self.y = y
    self.initialY = y -- set starting position as variable
    self.width = HEIGHT/8 -- set runner size
    self.height = HEIGHT/8
end

function Runner:draw()
    if self.y >= tower.y - tower.height/2 then -- if reached tower
        self.y = self.initialY -- set position back to starting position
    end
    sprite("Planet Cute:Character Boy", self.x, self.y, self.width,self.height) -- change
end

function Runner:touched(touch)

end

To size the tower and runner correctly, simply change the width and height in each of their init functions

tyguy2 · August 13, 2013, 8:21pm

Thank you! This works perfectly!