Portability | portable (needs FFI) |
---|---|

Stability | provisional |

Maintainer | felipe.lessa@gmail.com |

Functionality used by various modules and routines for initialization and change of global variables.

- initChipmunk :: IO ()
- type CpFloat = Double
- infinity :: CpFloat
- type Time = CpFloat
- type Angle = CpFloat
- type Distance = CpFloat
- type Damping = CpFloat
- resetShapeCounter :: IO ()
- contactPersistence :: StateVar CInt
- collisionSlop :: StateVar CpFloat
- type BiasCoef = CpFloat
- biasCoef :: StateVar BiasCoef
- constraintBiasCoef :: StateVar BiasCoef
- data Vector = Vector !CpFloat !CpFloat
- type Position = Vector
- fromAngle :: Angle -> Vector
- len :: Vector -> CpFloat
- normalize :: Vector -> Vector
- scale :: Vector -> CpFloat -> Vector
- toAngle :: Vector -> Angle
- dot :: Vector -> Vector -> CpFloat
- cross :: Vector -> Vector -> CpFloat
- perp :: Vector -> Vector
- project :: Vector -> Vector -> Vector
- rotate :: Vector -> Vector -> Vector
- unrotate :: Vector -> Vector -> Vector

# Initialization

Initilizes the Chipmunk library. This should be called once before using any functions of this library.

# Basic data types

Type synonym used to hint that the argument or result represents an angle in radians.

Type synonym used to hint that the argument or result represents a distance.

Type synonym used to hint that the argument or result represents a damping constant.

# Global variables

Chipmunk tries to maintain a very few number of global
variables to allow multiple `Space`

s to be used
simultaneously, however there are some.

## Shape counter

The shape counter is a global counter used for creating unique hash identifiers to the shapes.

resetShapeCounter :: IO ()Source

`resetShapeCounter`

reset the shape counter to its default
value. This is used to add determinism to a simulation. As
the ids created with this counter may affect the order in
which the collisions happen, there may be very slight
differences in different simulations. It may be very useful
to call `resetShapeCounter`

everytime you start a new
simulation.

However, be careful as you should not use shapes created
before a call to `resetCounter`

with shapes created after it
as they may have the same id. This means that you can't add
shapes created after the call to a space created before it.

## Contact persistence

This variable determines how long contacts should persist. It should be small as the cached contacts will only be close for a short time. (default is 3)

## Collision slop

The collision slop is the amount that shapes are allowed to penetrate. Setting this to zero will work just fine, but using a small positive amount will help prevent oscillating contacts. (default is 0.1)

## Bias coefficient

The amount of penetration to reduce in each step. Values should range from 0 to 1. Using large values will eliminate penetration in fewer steps, but can cause vibration. (default is 0.1)

## Constraint bias coefficient

Similar to the bias coefficient, but sets the default bias for all constraints. (default is 0.1)

# Vectors

Type synonym used to hint that the argument or result represents a position.

fromAngle :: Angle -> VectorSource

Constructs an unitary vector pointing to the given angle (in radians).

toAngle :: Vector -> AngleSource

`toAngle v`

is the angle that `v`

has
with the vector `Vector 1 0`

(modulo `2*pi`

).

perp :: Vector -> VectorSource

`perp v`

is a vector of same length as `v`

but perpendicular
to `v`

(i.e. `toAngle (perp v) - toAngle v`

equals `pi/2`

modulo `2*pi`

).