rotate()

Rotates the coordinate system.

By default, the positive x-axis points to the right and the positive y-axis points downward. The rotate() function changes this orientation by rotating the coordinate system about the origin. Everything drawn after rotate() is called will appear to be rotated.

The first parameter, angle, is the amount to rotate. For example, calling rotate(1) rotates the coordinate system clockwise 1 radian which is nearly 57˚. rotate() interprets angle values using the current angleMode().

By default, transformations accumulate. For example, calling rotate(1) twice has the same effect as calling rotate(2) once. The push() and pop() functions can be used to isolate transformations within distinct drawing groups.

Note: Transformations are reset at the beginning of the draw loop. Calling rotate(1) inside the draw() function won't cause shapes to spin.

Examples

rotate example 1

function setup()
  size(100, 100)
  windowTitle("rotate example")
  describe(
    "A white rectangle on a gray background. The rectangle's long axis runs from top-left to bottom-right."
  )
end

function draw()
  background(200)

  -- Rotate the coordinate system 1/8 turn.
  rotate(QUARTER_PI)

  -- Draw a rectangle at coordinates (50, 0).
  rect(50, 0, 40, 20)
end

rotate example 2

function setup() 
  size(100, 100)
  windowTitle('rotate() example')
  describe(
    "A white rectangle on a gray background. The rectangle's long axis runs from top-left to bottom-right."
  )
end

function draw() 
  background(200)

  -- Rotate the coordinate system 1/16 turn.
  rotate(QUARTER_PI / 2)

  -- Rotate the coordinate system another 1/16 turn.
  rotate(QUARTER_PI / 2)

  -- Draw a rectangle at coordinates (50, 0).
  rect(50, 0, 40, 20)
end

rotate example 3

function setup() 
  size(100, 100)
  windowTitle('rotate() example')
  -- Use degrees.
  angleMode(DEGREES)

  describe(
    "A white rectangle on a gray background. The rectangle's long axis runs from top-left to bottom-right."
  )
end

function draw() 
  background(200)

  -- Rotate the coordinate system 1/8 turn.
  rotate(45)

  -- Draw a rectangle at coordinates (50, 0).
  rect(50, 0, 40, 20)
end

rotate example 4

function setup() 
  size(100, 100)
  windowTitle('rotate() example')
  describe(
    'A white rectangle on a gray background. The rectangle rotates slowly about the top-left corner. It disappears and reappears periodically.'
  )
end

function draw() 
  background(200)

  -- Rotate the coordinate system a little more each frame.
  local angle = frameCount * 0.01
  rotate(angle)

  -- Draw a rectangle at coordinates (50, 0).
  rect(50, 0, 40, 20)
end

rotate()

Examples

Related