shape

Documentation

Overview

Package shape provides types to satisfy the Shape interface, which allows for containment and outline checks on two dimensional shapes.

Index

• Variables
• func ToOutline(shape Shape) func(...int) ([]intgeom.Point, error)
• type Eq
  • func (eq Eq) Above() In
  • func (eq Eq) Below() In
• type In
  • func AndIn(is ...In) In
  • func NotIn(i In) In
  • func OrIn(is ...In) In
  • func XRange(a, b float64) In
• type JustIn
  • func (ji JustIn) In(x, y int, sizes ...int) bool
  • func (ji JustIn) Outline(sizes ...int) ([]intgeom.Point, error)
  • func (ji JustIn) Rect(sizes ...int) [][]bool
• type Rect
  • func InToRect(i In) Rect
• type Shape

Variables

var (
	// Square will return true for any [x][y]
	Square = JustIn(func(x, y int, sizes ...int) bool {
		return true
	})

	// Rectangle will return true for any [x][y] in w, h
	Rectangle = JustIn(func(x, y int, sizes ...int) bool {
		w := sizes[0]
		h := sizes[0]
		if len(sizes) > 1 {
			h = sizes[1]
		}
		if x < w && y < h && x >= 0 && y >= 0 {
			return true
		}
		return false
	})
	// Diamond has a shape like the following:
	// . . t . .
	// . t t t .
	// t t t t t
	// . t t t .
	// . . t . .
	Diamond = JustIn(func(x, y int, sizes ...int) bool {
		radius := sizes[0] / 2
		return math.Abs(float64(x-radius))+math.Abs(float64(y-radius)) < float64(radius)
	})
	// Circle has a shape like the following:
	// . . . . . . .
	// . . t t t . .
	// . t t t t t .
	// . t t t t t .
	// . t t t t t .
	// . . t t t . .
	// . . . . . . .
	Circle = JustIn(func(x, y int, sizes ...int) bool {
		radius := sizes[0] / 2
		dx := math.Abs(float64(x - radius))
		dy := math.Abs(float64(y - radius))
		radiusf64 := float64(radius)
		if dx+dy <= radiusf64 {
			return true
		}
		return math.Pow(dx, 2)+math.Pow(dy, 2) < math.Pow(radiusf64, 2)
	})
	// Checkered has a shape like the following:
	// t . t . t .
	// . t . t . t
	// t . t . t .
	// . t . t . t
	// t . t . t .
	// . t . t . t
	Checkered = JustIn(func(x, y int, sizes ...int) bool {
		return (x+y)%2 == 0
	})
)

var (
	// Heart has an shape like the following:
	// . . t . t . .
	// . t t t t t .
	// t t t t t t t
	// t t t t t t t
	// . t t t t t .
	// . . t t t . .
	// . . . . . . .
	Heart = JustIn(OrIn(
		AndIn(
			XRange(0, 0.5), hf1.Below(), hf3.Above()),
		AndIn(
			XRange(0.5, 1), hf2.Below(), hf4.Above()),
	))
)

Functions

func ToOutline

func ToOutline(shape Shape) func(...int) ([]intgeom.Point, error)

ToOutline returns the set of points along the input shape's outline, if one exists.

Types

type Eq

type Eq func(x float64) (y float64)

Eq represents a basic equation-- a mapping of x values to y values. Specifically, this equation is expected to be significant to represent some part or all of a shape from -1 to 1. This range is chosen because it's often easier to write shape equations around the center of a graph.

func (Eq) Above

func (eq Eq) Above() In

Above returns an In which reports true for all x,y coordinates above the equation curve.

func (Eq) Below

func (eq Eq) Below() In

Below returns an In which reports true for all x,y coordinates below the equation curve.

type In

type In func(x, y int, sizes ...int) bool

In functions return whether the given coordinate lies in a shape.

func AndIn

func AndIn(is ...In) In

AndIn will combine multiple In functions into one, where if any of the shapes are false the result is false.

func NotIn

func NotIn(i In) In

NotIn returns the opposite of a given In function for any query

func OrIn

func OrIn(is ...In) In

OrIn will combine multiple In functions into one, where if any of the shapes are true the result is true.

func XRange

func XRange(a, b float64) In

XRange is an example In utility which returns values within a given relative range (where 0 = 0 and 1 = size). TODO: update to respect multiple sizes

type JustIn

type JustIn In

A JustIn lets an In function serve as a shape by automatically wrapping it in assistant functions for other utilites.

func (JustIn) In

func (ji JustIn) In(x, y int, sizes ...int) bool

In acts as the underlying In function

func (JustIn) Outline

func (ji JustIn) Outline(sizes ...int) ([]intgeom.Point, error)

Outline calls ToOutline on the JustIn

func (JustIn) Rect

func (ji JustIn) Rect(sizes ...int) [][]bool

Rect calls InToRect on a JustIn's In

type Rect

type Rect func(sizes ...int) [][]bool

A Rect is a function that returns a 2d boolean array of booleans for a given size, where true represents that the bounded shape contains the point [x][y].

func InToRect

func InToRect(i In) Rect

InToRect converts an In function into a Rect function. Know that, if you are planning on looping over this only once, it's better to just use the In function. The use case for this is if the same size rect will be queried on some function multiple times, and just having the booleans to re-access is needed.

type Shape

type Shape interface {
	In(x, y int, sizes ...int) bool
	Outline(sizes ...int) ([]intgeom.Point, error)
	Rect(sizes ...int) [][]bool
}

A Shape represents a rectangle of width/height size where for each x,y coordinate, either that value lies inside the shape or outside of the shape, represented by true or false. Shapes can be fuzzed along their border to create gradients of floats, and shapes can be queried to just produce a 2d boolean array of width/height size. Todo: consider if the number of coordinate arguments should be variadic, if width/height should not be combined and/or variadic, for additional dimension support