size(300,300)  # canvas
background(100)
stroke(0)
strokeWeight(1)

# specify angles as degrees, using radians() to convert. Going in a
# clockwise direction, fifth paramter is the start of the pie shape
# to draw, and the sixth parameter is the end of the pie shape.

# using 0 shows where the angles start from
fill(255,0,0) # red
arc(50,150, 50,50, radians(0), radians(90))

# a pac man shape
fill(255,255,0) # yellow
arc(100,150, 50,50, radians(45), radians(315))

# a pie wedge for pac man's mouth. starts where the above arc ends
fill(0,255,0) # green
arc(150,150, 50,50, radians(315), radians(405))

# you can also use negative numbers
fill(0,0,255) # blue
arc(200,150, 50,50, radians(-45), radians(45))

# the third and fourth parameters work just like ellipse()
# you can stretch things for example
fill(255,0,255) # purple
arc(250,150, 50,100, radians(315), radians(405))