Number
Number
A number that can be positive, negative, or zero.
The Number data type is useful for describing values such as position, size, and color. A number can be an integer such as 20 or a decimal number such as 12.34. For example, a circle's position and size can be described by three numbers:
circle(50, 20, 20)
circle(50, 20, 12.34)
Numbers support basic arithmetic and follow the standard order of operations: Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction (PEMDAS). For example, it's common to use arithmetic operators with p5.js' system variables that are numbers:
-- Draw a circle at the center
circle(width / 2, height / 2, 20)
-- Draw a circle that moves from left to right.
circle(frameCount * 0.01, 50, 20)
Here's a quick overview of the arithmetic operators:
1 + 2 -- Add
1 - 2 -- Subtract
1 * 2 -- Multiply
1 / 2 -- Divide
1 % 2 -- Remainder
1 ^ 2 -- Exponentiate
It's common to update a number variable using arithmetic. For example, an object's location can be updated like so:
x = x + 1
The statement above adds 1 to a variable x using the + operator. Lua does not have the assignment operators such as +=, -=, *=, /=, %=.
See Boolean for more information about comparisons and conditions.
Expressions with numbers can also produce special values when something goes wrong.
sqrt(-1) -- nan
1 / 0 -- inf
The value nan stands for Not-A-Number. nan appears when calculations or conversions don't work. inf stands for infinity, a value that's larger than any number. It appears during certain calculations.
Examples
function setup()
size(100, 100)
background(200)
-- Draw a circle at the center.
circle(50, 50, 70)
-- Draw a smaller circle at the center.
circle(width / 2, height / 2, 30)
describe('Two concentric, white circles drawn on a gray background.')
end
function setup()
size(100, 100)
describe('A white circle travels from left to right on a gray background.')
end
function draw()
background(200)
circle(frameCount * 0.05, 50, 20)
end