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https://github.com/stetre/moonchipmunk

Lua bindings for Chipmunk2D
https://github.com/stetre/moonchipmunk

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Lua bindings for Chipmunk2D

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## MoonChipmunk: Lua bindings for Chipmunk2D



MoonChipmunk is a Lua binding library for Scott Lembcke's [Chipmunk2D](http://chipmunk-physics.net/) physics engine.



It runs on GNU/Linux and on Windows (MSYS2/MinGW) and requires

[Lua](http://www.lua.org/) (>=5.3) and [Chipmunk2D](http://chipmunk-physics.net/downloads.php) (>= 7.0.3).



_Author:_ _[Stefano Trettel](https://www.linkedin.com/in/stetre)_



[![Lua logo](./doc/powered-by-lua.gif)](http://www.lua.org/)



#### License



MIT/X11 license (same as Lua). See [LICENSE](./LICENSE).



#### Documentation



See the [Reference Manual](https://stetre.github.io/moonchipmunk/doc/index.html).



#### Getting and installing



Setup the build environment as described [here](https://github.com/stetre/moonlibs), then:



```sh

$ git clone https://github.com/stetre/moonchipmunk/

$ cd moonchipmunk

moonchipmunk$ make

moonchipmunk$ sudo make install

```



#### Example



The example below is a port of the ["Hello Chipmunk (World)" example](http://chipmunk-physics.net/release/ChipmunkLatest-Docs/#Intro-HelloChipmunk) from the Chipmunk2D manual.



Other examples, including a Lua port of the Chipmunk2D demos, can be found in the **examples/** directory.



```lua

-- MoonChipmunk example: hello.lua

local cp = require("moonchipmunk")



-- Create an empty space and set the gravity for it.

local space = cp.space_new()

space:set_gravity({0, -100})

  

-- Add a static line segment shape for the ground.

-- We'll make it slightly tilted so the ball will roll off.

-- We attach it to a static body to tell Chipmunk it shouldn't be movable.

local ground = cp.segment_shape_new(space:get_static_body(), {-20, 5}, {20, -5}, 0)

ground:set_friction(1)

space:add_shape(ground)



-- Now let's make a ball that falls onto the line and rolls off.

-- First we need to make a body to hold the physical properties of the object.

-- These include the mass, position, velocity, angle, etc. of the object.

-- Then we attach collision shapes to the body to give it a size and shape.

local radius = 5

local mass = 1

-- The moment of inertia is like mass for rotation

-- Use the cp.moment_for*() functions to help you approximate it.

local moment = cp.moment_for_circle(mass, 0, radius, {0, 0})

  

 -- The space:add*() methods return the thing that you are adding.

-- It's convenient to create and add an object in one line.

local ballBody = space:add_body(cp.body_new(mass, moment))

ballBody:set_position({0, 15})

  

-- Now we create the collision shape for the ball.

-- You can create multiple collision shapes that point to the same body.

-- They will all be attached to the body and move around to follow it.

local ballShape = space:add_shape(cp.circle_shape_new(ballBody, radius, {0, 0}))

ballShape:set_friction(0.7)

  

-- Now that it's all set up, we simulate all the objects in the space by

-- stepping forward through time in small increments called steps.

-- It is *highly* recommended to use a fixed size time step.

local timeStep = 1.0/60.0

for time = 0, 2, timeStep do

    local pos = ballBody:get_position()

    local vel = ballBody:get_velocity()

   print(string.format(

        "Time is %5.2f. ballBody is at (%5.2f, %5.2f). It's velocity is (%5.2f, %5.2f)",

        time, pos[1], pos[2], vel[1], vel[2]))

   space:step(timeStep)

end

 

-- No need to delete objects here (they are are automatically deleted ad exit).

```



The script can be executed at the shell prompt with the standard Lua interpreter:



```shell

$ lua hello.lua

```



#### See also



* [MoonLibs - Graphics and Audio Lua Libraries](https://github.com/stetre/moonlibs).