primitives

Primitive (line, rectangle and circle) patterns. This module provides convenience functions for the generation of basic pattern shapes. So far including lines, squares/rectangles and circle rasters.

-- Draw some squares
local square_pattern = primitives.square(5)      -- 5x5
local rectangle_pattern = primitives.square(3,5) -- 3x5

-- Draw a line
local line = primitives.line(cell.new(0,0), cell.new(10,10))

-- Draw a circle about (0,0) with radius 5
local circle = primitives.circle(5)

primitives.square

Generate a square pattern.

local sq = primitives.square(5)
local rect = primitives.square(3, 5)

Parameters:

Name	Type	Description
x	number	size in x
y	number?	size in y (default y = x)

Returns:

• forma.pattern — square pattern of size {x, y}

primitives.line

Generate a line pattern. According to Bresenham's line algorithm.

local line = primitives.line(cell.new(0, 0), cell.new(10, 10))

Parameters:

Name	Type	Description
start	forma.cell	a cell denoting the start of the line
finish	forma.cell	a cell denoting the end of the line

Returns:

• forma.pattern — a pattern consisting of a line between start and finish

primitives.quad_bezier

Draw a quadratic bezier curve. Uses an algorithm from rosettacode.org. This function returns both a pattern consisting of the drawn bezier curve, and a list of points along the curve. This may be important in case the curve back-tracks over existing cells, which cannot be represented in a forma pattern. The full pattern consists of N of these points, joined by bresenham line segments.

local curve, points = primitives.quad_bezier(
    cell.new(0, 0), cell.new(5, 10), cell.new(10, 0))

Parameters:

Name	Type	Description
start	forma.cell	a cell denoting the start of the curve
control	forma.cell	a cell denoting the control point of the curve
finish	forma.cell	a cell denoting the end of the curve
N	integer?	number of line-segments to construct the curve with (default: 20)

Returns:

• forma.pattern — a pattern consisting of the bezier curve
• forma.cell[] — an ordered list of cells consisting of points along the curve

primitives.circle

Generate a circle pattern. Bresenham algorithm.

local circle = primitives.circle(5)

Parameters:

Name	Type	Description
r	number	the radius of the circle to be drawn

Returns:

• forma.pattern — circular pattern of radius r and origin (0,0)