Graphics.Chalkboard.Types

This module contains the types used by chalkboard, except Board itself.

Basic types

type UI = R

Unit Interval: value between 0 and 1, inclusive.

type R = Float

A real number.

type Point = (R, R)

A point in R2.

type Radian = Float

Angle units

Overlaying

class Over c where

For placing a value literally over another value. The 2nd value might shine through. The operation must be assocative.

Methods

over :: c -> c -> c

Instances

Over Bool

Over RGB

Over Gray

Over (Maybe a)

Over (Z c)

(Scale c, Lerp c) => Over (Alpha c)

Over c => Over (Board c)

stack :: Over c => [c] -> c

stack stacks a list of things over each other, where earlier elements are over later elements. Requires non empty lists, which can be satisfied by using an explicity transparent Board as one of the elements.

Scaling

class Scale c where

Scale something by a value. scaling value can be bigger than 1.

Methods

scale :: R -> c -> c

Instances

Scale R

Scale RGB

Scale (Board a)

Linear Interpolation

class Lerp a where

Linear interpolation between two values.

Methods

lerp :: a -> a -> UI -> a

Instances

Lerp R

Lerp RGB

Lerp a => Lerp (Maybe a)

(Lerp a, Lerp b) => Lerp (a, b)

Lerp over pairs

Averaging

class Average a where

Average a set of values. weighting can be achived using multiple entries.

Methods

average :: [a] -> a

average is not defined for empty list

Instances

Average R

Average RGB

Alpha Channel support

data Alpha c

Channels with alpha component, the channel is pre-scaled.

Constructors

Alpha c !UI

Instances

Show c => Show (Alpha c)

(Scale c, Lerp c) => Over (Alpha c)

alpha :: c -> Alpha c

alpha builds something that has an alpha channel, and is completely opaque.

transparent :: c -> Alpha c

transparent builds something that has an alpha channel, and is completely transparent.

withAlpha :: Scale c => UI -> c -> Alpha c

withAlpha builds somethings that has a specific alpha value.

unAlpha :: Scale c => Alpha c -> c

unAlpha removes the alpha component, and returns the channel inside.

Z buffer support

data Z c

A Z buffer style Z value for a point, where lower numbers are nearer the viewer. Assumes no transparency.

Constructors

Z c R

Instances

Show c => Show (Z c)

Over (Z c)

Constants

nearZero :: R

Close to zero; needed for Over (Alpha c) instance.