Hobby
Predefined Shapes

Predefined Shapes

Hobby provides predefined shapes that are already solved and ready to use. They can be transformed and styled without calling build().

Available Shapes

fullcircle()

A unit circle with diameter 1, centered at the origin.

local circle = h.fullcircle()

halfcircle()

The upper half of the unit circle.

local half = h.halfcircle()

quartercircle()

A quarter circle (first quadrant arc).

local quarter = h.quartercircle()

unitsquare()

A unit square from (0,0) to (1,1).

local square = h.unitsquare()

Using Shapes

Predefined shapes are typically scaled and positioned:

local h = require("hobby")

-- A circle with diameter 50, centered at (100, 100)
local circle = h.fullcircle()
    :scaled(50)
    :shifted(100, 100)
    :stroke("blue")

-- A square with side 30, positioned at (50, 50)
local square = h.unitsquare()
    :scaled(30)
    :shifted(50, 50)
    :stroke("red")

h.svg()
    :padding(10)
    :add(circle)
    :add(square)
    :write("shapes.svg")

Shapes example

Shape Properties

length

Returns the number of segments in the path.

local circle = h.fullcircle():scaled(50)
print(circle.length)  -- 8

local square = h.unitsquare():scaled(30)
print(square.length)  -- 4

Points

point(x, y)

Creates a point that can be used with paths and transformations.

local p = h.point(100, 50)

Points support arithmetic operations:

local a = h.point(10, 20)
local b = h.point(30, 40)

local sum = a + b           -- (40, 60)
local diff = a - b          -- (-20, -20)
local scaled = a * 2        -- (20, 40)
local neg = -a              -- (-10, -20)

dir(angle)

Creates a unit vector at the given angle (in degrees).

local right = h.dir(0)      -- (1, 0)
local up = h.dir(90)        -- (0, 1)
local diag = h.dir(45)      -- (0.707, 0.707)

Geometry Helpers

midpoint(a, b)

Returns the midpoint between two points.

local mid = h.midpoint(h.point(0, 0), h.point(100, 100))
-- Result: (50, 50)

distance(a, b)

Returns the Euclidean distance between two points.

local d = h.distance(h.point(0, 0), h.point(3, 4))
-- Result: 5

between(a, b, t)

Returns the point at parameter t along the line from a to b.

local p = h.between(h.point(0, 0), h.point(100, 0), 0.25)
-- Result: (25, 0)
PathsTransformations