Hi all.

3.2 integrates the Chipmunk physics engine with Lua bindings. This allows us create fun games with the physics.
However there is just one problem. It's pretty complex.
So here is some useful info if you want to start programming.

1. The API documentation for 3.2
Download it at http://education.ti.com/nspire/scripting-api .
It's a must have in order to find all the API function names (duh :P )

2. The online chipmunk docs
http://chipmunk-physics.net/release/Chipmunk-5.x/Chipmunk-5.3.4-Docs/
Even though it describes the C API, it shows how the concepts of the engine and how it's structured.
And most Lua functions have similar names to the C ones.
You will find yourself checking this resource often when you start programming with the engine ;)

3. A tutorial (although for the C API)
http://www.alexandre-gomes.com/articles/chipmunk/
This tutorial helps you understand the concepts and inner workings of the physics engine.

4. Example code (by me)


I spend some time making this code, so please take care of it  ;)

5. Take a look at other exisiting activities for the TI-Nspire that use the physics engine
http://education.ti.com/calculators/tisciencenspired/US/Activities/Detail?sa=5029&id=17888

And last but not least ...
Have fun !

Yeah, it's indeed a very nice addition

However, don't expect super complex and graphically advanced games to be possible
It's still a calculator, and the Lua bindings are of course a bit slower than the C one. (This is why Ndless 3.2 will be awesome ).
But a (good functioning) Angry Birds clone should be possible.

I'm not sure if I'm going to give this a try in my programs, but it is interesting.

Thanks for gathering these resources! 


space = pSpace(9.8)

got turned into

space = pSpace(9.

in your code.

Yeah, I saw that. 

So, I looked into the documentation, and could not find any sign of liquidsimulation. Is this present in the physics lib or not?
It's sad to see that noone has made a game with it yet, someone should try this out

It is so laggy that you could not make any complex nor simple game with it.
Adriweb, Jim and me tried the basic samples of Chipmunk demo. None of them can run smoothly on the handheld. It seems TI Enginners are only taking care of the PC version witch is a shame.
Sad to say but better recode it your own physic engine...

Sounds interesting, any one have a video?

Sounds interesting, any one have a video?

A video of the chipmunk engine? Well, if you have the student software a handheld, you could try the code Jim posted above (they're really nice tbh)

@Nick My eat nethams game seems to run somewhat faster on 3.2 than it did on 3.1. The lobsters definitely fall smoother when setting it to the 100% spawn rate. It's not much of an improvement, but to me it seems to be something like 5-10%. It also could be I'm just imagining it, sadly I do not own 2 CXes so I can't test :p

That's what I hoped, that it would be faster, but still pff, I guess we could never expect it to be superlightningthunderboltfast, but at least a little afster than now xs but yeah, any improvement is nice..

Thank you jim's !
It's so hard to start using physics, your example code really helped me

Hi jims



I'm back with my falldown but I have 2 problems :
- The ball don't falls in the hole --'
- It slows down so much : why ?

------------------------------------------------
----------- LUA FALLDOWN, BY ANTOX98 -----------
------------------------------------------------

platform.apilevel = "2.0"

require "physics"

----------------------
----- BALL CLASS -----
----------------------

Ball = class()
Seg = class()

function Ball:init(x, y, w, mass)   
    self.width = w
    self.body = physics.Body(mass, physics.misc.momentForCircle(mass, 0, 10, ZERO))
    self.body:setPos(physics.Vect(x, y))
    self.body:setMass(mass)
    self.shape = physics.CircleShape(self.body, w, ZERO)
    self.shape:setRestitution(0.6)
    self.shape:setFriction(0.6)
end

function Seg:init(x1, y1, x2, y2)
    local a, b = physics.Vect(x1, y1), physics.Vect(x2, y2)       
    local mass = physics.misc.INFINITY()
    self.coor = {x1,y1,x2,y2}
    self.body = physics.Body(mass, physics.misc.momentForSegment(mass, a, b))
    --self.body:setPos(physics.Vect(x1, y1))
    self.body:setMass(mass)
    self.shape = physics.SegmentShape(self.body, a, b, 18)
    self.shape:setRestitution(0.6)
    self.shape:setFriction(0.6)
end

function Ball:paint(gc)
    local p = self.body:pos()
    local x, y = p:x(), p:y()
    local r = self.width / 2
   
    gc:setColorRGB(255,0,0)
    gc:fillArc(x+r, y+r , self.width, self.width, 0, 360)
end

function Seg:paint(gc)
   
    local a = self.shape:a()
    local b = self.shape:b()
    gc:setPen("thick")
    gc:setColorRGB(0,0,0)
    gc:drawLine(a:x(), a:y(), b:x(), b:y())
end

function initGame()
    w = 318
    h = 212
   
    ZERO = physics.Vect(0,0)
    LARGE = physics.misc.INFINITY()
   
    space = physics.Space()
    space:setGravity(physics.Vect(0,9.8))
   
    count = 100
   
    walls = {Seg(0,0,0,h), Seg(0,h,w,h), Seg(w,h,w,0)}
    for i = 1, #walls do
        space:addShape(walls[i].shape)   
    end
   
    seg = {}
    --space:addBody(sol.body)

   
    ball = Ball(w/2-10, 30, 20, 1000)
   
    space:addBody(ball.body)
    space:addShape(ball.shape)
   
    timer.start(0.01)
end
initGame()

function on.timer()
    space:step(0.1)
   
    if count == 100 then
        count = 0
        generate()
    else   
        count = count + 1
    end   
    moveSeg(0.5)
    platform.window:invalidate()
end

function generate()
    r = math.random(0, w-40)
   
    seg[#seg+1] = Seg(0, h, r, h)
    seg[#seg+1] = Seg(r+40, h, w, h)
    space:addShape(seg[#seg-1].shape)
    space:addShape(seg[#seg].shape)
end

function moveSeg(n)
    for i = 1, #seg do
        seg[i].coor = {seg[i].coor[1],seg[i].coor[2]-n,seg[i].coor[3],seg[i].coor[4]-n}
        local a, b = physics.Vect(seg[i].coor[1], seg[i].coor[2]), physics.Vect(seg[i].coor[3], seg[i].coor[4])       
        local mass = physics.misc.INFINITY()       
        seg[i].body = physics.Body(mass, physics.misc.momentForSegment(mass, a, b))
        --self.body:setPos(physics.Vect(x1, y1))
        seg[i].body:setMass(mass)
        seg[i].shape = physics.SegmentShape(seg[i].body, a, b, 18)
        seg[i].shape:setRestitution(0.6)
        seg[i].shape:setFriction(0.6)
        space:addShape(seg[i].shape)
    end   
end

function on.arrowKey(key)
    if key == "right" then
        ball.body:setAngVel(5)
    elseif key == "left" then
        ball.body:setAngVel(-5)
    end
end

function on.paint(gc)
    ball:paint(gc)   
    for i = 1, #seg do
        seg[i]:paint(gc)
    end
 
   
end