Objective
- Draw graphics on the screen using turtle graphics
Overview
- Turtle graphics is like being able to program a little robot that can draw on the screen.
- Python must have Tk support installed to be able to use turtle graphics.
- Turtle graphics was created in the mid 1960s for the Logo programming language by Feurzig, Papert, and Solomon.
- See https://docs.python.org/3.6/library/turtle.html for documentation.
- Use "import turtle" to get access to the turtle graphics library
Common turtle commands
| Function | Purpose |
|---|---|
| degrees(n=360) | set turtle to use n degrees for a full circle |
| radians() | set turtle to use radian measurements: degrees(2*Pi) |
| position(), pos() | returns turtle coordinate |
| forward(n), fd(n) | moves turtle n units in direction it is facing |
| back(n), bk(n), backward(n) | moves turtle n units opposite to direction it is facing |
| heading() | returns direction turtle is facing in degrees or radians |
| right(n), rt(n) | turns turtle to right by n degrees or radians |
| left(n), lt(n) | turns turtle to right by n degrees or radians |
| goto(x,y), setpos(x,y), setposition(x,y) |
moves turtle to position specified |
| setx(x) | changes turtle's x coordinate, but leaves y as it is |
| sety(y) | changes turtle's y coordinate, but leaves x as it is |
| xcor() | returns the turtle's x coordinate |
| ycor() | returns the turtle's y coordinate |
| setheading(n), seth(n) | sets turtle's heading to n degrees or radians |
| heading() | returns the turtle's heading |
| home() | sets turtle's coordinates to (0, 0) and resets heading |
| pendown(), pd(), down() | makes turtle draw when moving |
| penup(), pu(), up() | makes turtle not draw when moving |
| pensize(n), width(n) | sets width of pen to n |
| pensize(), width() | returns width of pen |
| isdown() | returns True if pen is down, otherwise returns False |
| circle(radius, extent, steps) | draws all or part of a circle or regular polygon |
| speed(n) | set speed of turtle (1 = slow, 10 = fast) |
| speed() | returns speed of turtle |
| distance(x,y) | returns distance from turtle to (x,y) |
| towards(x,y) | returns angle to (x,y) depending on mode |
| color() | returns current turtle drawing color |
| color(color) | sets current turtle drawing color |
| fillcolor() | returns current turtle drawing fill color |
| fillcolor(color) | sets current turtle drawing fill color |
| begin_fill() | specifies that shape to be filled will be drawn next |
| end_fill() | specifies that shape to be filled has finished being drawn |
| hideturtle(), ht() | makes the turtle invisible |
| showturtle(), st() | makes the turtle visible |
| isvisible() | returns True if turtle is visible, otherwise returns False |
| begin_poly() | starts recording vertices of polygon with current position |
| end_poly() | stop recording polygon vertices and connect current position to first position |
| get_poly() | returns the last recorded polygon |
| bgcolor() | returns the current background color |
| bgcolor(color) | sets the current background color |
| bgpic() | returns the filename of the current background picture |
| bgpic(filename) | sets the current background picture |
| clear(), clearscreen() | clears the screen |
| textinput(title, prompt) | opens a dialog to get text input |
| numinput(title, prompt) | opens a dialog to get numeric input |
| mode() | return current turtle mode ("standard", "logo", or "world") |
| mode(s) | sets current turtle mode ("standard", "logo", or "world") |
| colormode() | returns the color mode (1.0 or 255) |
| colormode(n) | sets the color mode (1.0 or 255) |
| window_width() | returns width of turtle graphics window |
| window_height() | returns height of turtle graphics window |
| bye() | shuts turtle graphics window |
Draw flag of Japan
import turtle turtle.speed(0) turtle.hideturtle() turtle.bgcolor("yellow") # draw rectangle turtle.width(3) turtle.color("black") turtle.fillcolor("white") turtle.penup() turtle.goto(-100, 50) turtle.setheading(0) turtle.pendown() turtle.begin_fill() turtle.forward(200) turtle.right(90) turtle.forward(100) turtle.right(90) turtle.forward(200) turtle.right(90) turtle.forward(100) turtle.end_fill() # draw circle turtle.color("red") turtle.fillcolor("red") turtle.penup() turtle.goto(35, 0) turtle.setheading(90) turtle.pendown() turtle.begin_fill() turtle.circle(35) turtle.end_fill()
Draw a smiley face
import turtle turtle.color("black") turtle.bgcolor("yellow") turtle.width(4) turtle.hideturtle() turtle.speed(0) turtle.penup() turtle.goto(-75,150) turtle.pendown() turtle.begin_fill() turtle.circle(10) turtle.end_fill() turtle.goto(-75,145) turtle.pendown() turtle.begin_fill() turtle.circle(10) turtle.end_fill() turtle.penup() turtle.goto(75,150) turtle.pendown() turtle.begin_fill() turtle.circle(10) turtle.end_fill() turtle.goto(75,145) turtle.pendown() turtle.begin_fill() turtle.circle(10) turtle.end_fill() turtle.width(15) turtle.penup() turtle.goto(0,-25) turtle.pendown() turtle.circle(120,90) turtle.penup() turtle.setheading(180) turtle.goto(0,-25) turtle.pendown() turtle.circle(-120,90)
Draw a wobbly jagged spiral
import turtle import random random.seed() turtle.colormode(255) turtle.speed(0) turtle.ht() x = 10 for i in range(1, 2000): turtle.forward(x) turtle.right(36) if i % 5 == random.randint(0, 4): x = x + random.randint(0,4) if i % 5 == random.randint(0, 4): turtle.pencolor(random.randint(0,255),random.randint(0,255),random.randint(0,255)) if i % 5 == random.randint(0, 4): turtle.width(random.randint(1,3))