Python Course design Notes (iii) Turtle drawing Library (Turtle Library)

Example: Draw a Python

#Turtle: Drawing Library (Turtle Library)ImportTurtleturtle.setup (650,350,200,200) Turtle.penup () turtle.fd (-250) Turtle.pendown () turtle.pensize (25) Turtle.pencolor ("Purple") Turtle.seth (-40) forIinchRange (4): Turtle.circle (40,80) turtle.circle (-40,80) turtle.circle (40,80/2) TURTLE.FD (40) turtle.circle (16,180) TURTLE.FD (40*2/3) Turtle.done ()

Turtle Library: entry-level graphic drawing library, standard library

Python implementation of turtle drawing system

A turtle on the canvas, the canvas unit is the pixel.

The position of the drawing form relative to the screen:　

Turtle.setup (Width,height,startx,starty) #绘图窗体的大小和位置, not required

Turtle.setup (width,height) #绘图窗体默认在屏幕中间

Coordinate system:

Space Coordinate system:

　　Absolute Coordinates: The initial position is in the center of the canvas

Set Turtle crawling Destination: Turtle.goto (100,100)

　　

　　Turtle Coordinates: for the turtle's own perspective

Change the direction of turtle crawling:

Turtle.circle (R,angle)

TURTLE.BK (d) #后退d

TURTLE.FD (d) #前进d

　　

Angular coordinate system:

Changing the turtle's travel angle

　　Absolute angle: The x-axis relative to the canvas

Turtle.seth (45)

　　

　　Turtle angle: Relative to the turtle's current orientation

Turtle.left (angle)

Turtle.right (angle)

　　

Color System　

Turtle is an RGB color system (with small values by default)

Turtle.colormode (mode) #mode = 1.0 decimal value, mode=255 integer value

Turtle.colormode (1.0) Turtle.pencolor (1,1,0.4)

analysis of grammatical elements of turtle library

Import

The From library import function (*) #不用在前面加库名, but causes a function name conflict

Import library as library's nickname #重新命名为简单的库名, commonly used

Brush control functions

After the brush operation has been effective, generally paired appear turtle.penup () Turtle.pendown ()

Brush size turtle.pensize (width) = turtle,width (width)

Brush color Turtle.pencolor (color) #color为rgb或字符串, RGB tuple values:

(1,0.1,0.3) ("White") ((1,3,233))

Motion control function: Make turtle climb up-draw line

Motion path functions (lines and curves)

Turtle.forward (d) = TURTLE.FD (d) #向前行进, D is backward when negative

Turtle.circle (R,extent=none) #曲线半径, the center of the turtle to the left of R, the default to walk the entire circle

Direction control function: Absolute angle & relative angle

　　Just change the turtle to turn!!

Absolute angle: Relative to the x-axis in the absolute coordinate system

turtle.setheading (angle) = Turtle.seth (angle)

Relative angle: Relative to the turtle's current orientation

Turtle.left (angle)

Turtle.right (angle)

　　

　　

　　

　

　　

Python Course design Notes (iii) Turtle drawing Library (Turtle Library)