Easily take you to the gate of turtle drawing

Turtle, Also called Turtle renderer , Use Turtle Kuhua is also called turtle drawing .Python Of turtle Kuo is Python A very popular function library of drawing image in language , Imagine a little turtle , On a horizontal axis x、 The vertical axis is y The origin of the coordinate system ,(0,0) Position start , It is controlled by a set of function instructions , Moving in this plane coordinate system , So it draws a graph on its crawling path .

1. Install and import turtle library

open PyCharm Terminal or cmd Command line window , Enter the command

pip install turtle

To complete the installation , Use in the compiler after installation import turtle Just import

2. Basic drawing commands

Imagine ourselves drawing on a picture book , In the center of the canvas, create a x-y Coordinate system , First, you need to determine the location of the drawing , The second is the direction of drawing . And in the turtle in , The default direction of drawing is right , Location is （0,0）, That is, the center of the canvas , And canvas coordinates （x,y） The range of change is
$-220\le x\le 220$,$-220\le y\le 220$.

There are many commands for manipulating turtle drawings , These commands can be divided into 3 Kind of :
A motion command for a brush ; A control command for a brush ; Another is the global control command ;

1. Brush motion command

command	explain
turtle.forward(distance)	Move to brush distance Pixel length
turtle.backward(distance)	Move in the opposite direction of the brush distance Pixel length
turtle.right(degree)	Move clockwise degree degree
turtle.left(degree)	Move counterclockwise degree degree
turtle.penup()	write , That is, when the brush moves, it does not draw graphics
turtle.pendown()	Set pen to paper , Draw the graph when you move after writing
turtle.goto(x,y)	Move the brush to the coordinate (x,y) The location of
turtle.speed(speed)	Change the speed of the brush ,speed=0 It's the biggest when I'm young
turtle.circle()	A circle , Radius is positive （ negative ）, It is on the left of the brush （ Right ） Side flower circle

2. Brush control command

command	explain
turtle.pensize(width)	Set the width of the drawing
turtle.pencolor(color)	Set the color of the brush
turtle.fillcolor(color)	Set the color of the filled figure
turtle.color(color1,color2)	Set the color of the brush and the color of the filled figure at the same time
turtle.begin_fill()	Ready to start filling in figures
turtle.end_fill()	Filling complete
turtle.hideturtle()	Hide arrows to show
turtle.showturtle()	And hideturtle（） contrary , Show arrows for

3. Global control command

command	explain
turtle.clear(()	Empty turtle window , however turtle The position and direction of the turtle will not change
turtle.reset()	Clear the window , Reset turtle The state is the starting state
turtle.undo()	Undo the last turtle action
turtle.write(s)	Put the text content s Write in the direction of the current turtle

3.turtle A simple case

1. love

import turtle as t

t.speed(0)
def curvemove():
    for i in range(200):
        t.right(1)
        t.forward(1)
t.color('red','pink')
t.begin_fill()
t.left(140)
t.forward(111.65)
curvemove()
t.left(120)
curvemove()
t.forward(111.65)
t.end_fill()
t.hideturtle()
t.done()

2. Colorful balls floating

import turtle as t
import random #  random number 
t.colormode(255)
t.speed(0)
for i in range(20):
    red = random.randint(0, 255)
    green = random.randint(0, 255)
    blue = random.randint(0, 255)

    #  Random coordinates  x y
    x = random.randint(-220, 220)
    y = random.randint(0, 220)

    #  write 
    t.penup()
    t.goto(x, y)
    t.pendown()

    t.color(red, green, blue)
    t.begin_fill()
    t.circle(30)
    t.end_fill()
    t.right(90)
    t.forward(30)
    t.left(90)

# RGB red green blue
t.hideturtle()
t.done()

3. shield

import turtle as t
t.speed(0)
t.penup()
t.goto(0,-200)
t.pendown()
t.color('red')
t.begin_fill()
t.circle(200)
t.end_fill()

t.penup()
t.goto(0,-150)
t.pendown()
t.color('white')
t.begin_fill()
t.circle(150)
t.end_fill()

t.penup()
t.goto(0,-100)
t.pendown()
t.color('red')
t.begin_fill()
t.circle(100)
t.end_fill()

t.penup()
t.goto(0,-50)
t.pendown()
t.color('blue')
t.begin_fill()
t.circle(50)
t.end_fill()

#  Draw five pointed stars 
t.penup()
t.goto(-40,10)
t.pendown()
t.color('white')
t.begin_fill()
for i in range(5):
    t.forward(80)
    t.right(144)
t.end_fill()
t.hideturtle()
t.done()

All in all , As long as you master the mathematical composition skills and principles of graphics , Any complex figure we can pass through a loop +turtle The drawing command is completed .