Creating a turtle

14 Jan 2018 0 Comments

Let’s have some fun and create the real turtle drawing using Turtle. Inspired by child’s drawing of turtle we are going to draw and paint figures which consists of arcs and straight lines.

Turtle

Preparation

Creating a new project

cargo new --bin creating_a_turtle

Adding Turtle as a Dependency

[dependencies]
turtle = "^1.0.0-alpha.8"

Changing the src/main.rs

extern crate turtle;

use turtle::{Turtle, Color, color};

const SIZE: f64 = 1.0;
const SHELL_COLOR: Color = Color {red: 62.0, green: 114.0, blue: 29.0, alpha: 1.0};
const BODY_COLOR: Color = Color {red: 119.0, green: 178.0, blue: 85.0, alpha: 1.0};
const EYE_COLOR: Color = color::BLACK;

fn main() {
    let mut turtle = Turtle::new();
    turtle.set_speed(8);

    // ...
}

Basic steps

Lets divide the turtle on the different parts and draw it separatly. Our turtle consists of the next parts:

Shell Tail Two legs Neck Head Eye Highlights on the shell

To draw arcs we need to use the loops which are determine tilt angle and the length. The more sophisticated the figure is the more loops it requires to make.

Shell

Adding code to the main function

turtle.pen_up();
turtle.set_x(-280.0);
turtle.set_y(-90.0);

draw_shell(&mut turtle);

Creating draw_shell function

fn draw_shell(turtle: &mut Turtle) {
    turtle.set_fill_color(SHELL_COLOR);
    turtle.begin_fill();

    for _ in 0..180 {
        turtle.forward(SIZE);
        turtle.right(1.0);
    }

    for _ in 0..90 {
        turtle.forward(SIZE / 3.0);
        turtle.right(1.0);
    }

    turtle.set_speed(5);
    let d = SIZE * 360.0 / std::f64::consts::PI;
    turtle.forward(d - d / 3.0);
    turtle.set_speed(10);

    for _ in 0..90 {
        turtle.forward(SIZE / 3.0);
        turtle.right(1.0);
    }

    turtle.end_fill();
}

Shell

Tail

Adding code to the main function

draw_tail(&mut turtle);

Creating draw_tail function

fn draw_tail(turtle: &mut Turtle) {
    turtle.set_fill_color(BODY_COLOR);
    turtle.begin_fill();

    turtle.left(90.0);
    turtle.forward(SIZE);

    for _ in 0..45 {
        turtle.forward(SIZE / 3.0);
        turtle.left(1.0);
    }

    turtle.forward(SIZE * 3.0);

    for _ in 0..25 {
        turtle.forward(SIZE / 3.0);
        turtle.left(6.0);
    }

    turtle.forward(SIZE * 9.0);
    turtle.right(6.0);
    turtle.forward(SIZE * 8.0);

    turtle.end_fill();
}

Tail

Legs

Adding code to the main function

turtle.pen_up();
turtle.right(55.0);
turtle.forward(SIZE * 10.0);
turtle.right(55.0);

// Back leg
draw_leg(&mut turtle);

turtle.right(86.5);
turtle.forward(SIZE * 55.0);
turtle.right(86.0);

// Front leg
draw_leg(&mut turtle);

Creating draw_leg function

fn draw_leg(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..15 {
        turtle.forward(SIZE);
        turtle.left(0.5);
    }

    for _ in 0..90 {
        turtle.forward(SIZE / 6.0);
        turtle.left(1.0);
    }

    turtle.forward(SIZE * 3.0);

    for _ in 0..90 {
        turtle.forward(SIZE / 6.0);
        turtle.left(1.0);
    }

    turtle.forward(SIZE * 14.5);

    turtle.end_fill();
}

Legs

Neck

Adding code to the main function

turtle.right(54.5);
turtle.forward(SIZE * 8.0);

draw_neck(&mut turtle);

Creating draw_neck function

fn draw_neck(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..15 {
        turtle.forward(SIZE * 3.0);
        turtle.left(1.5);
    }

    turtle.end_fill();
    turtle.begin_fill();

    turtle.left(100.0);
    turtle.forward(SIZE * 20.0);
    turtle.left(80.0);

    for _ in 0..4 {
        turtle.forward(SIZE * 3.7);
        turtle.left(1.5);
    }

    turtle.left(30.0);

    for _ in 0..27 {
        turtle.forward(SIZE);
        turtle.right(1.0);
    }

    turtle.end_fill();
}

Neck

In our case the most difficult part of the turtle is head. It requires six loops to draw. There was a way to draw it as one circle but I’ve decided to make it look a like a real turtle’s head.

Adding code to the main function

turtle.right(172.6);
turtle.forward(SIZE * 40.0);
turtle.right(110.0);

draw_head(&mut turtle);

Creating draw_head function

fn draw_head(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..20 {
        turtle.forward(SIZE * 1.2);
        turtle.left(1.0);
    }

    for _ in 0..10 {
        turtle.forward(SIZE * 1.2);
        turtle.left(4.0);
    }

    for _ in 0..10 {
        turtle.forward(SIZE / 1.5);
        turtle.left(7.0);
    }

    for _ in 0..10 {
        turtle.forward(SIZE);
        turtle.left(2.0);
    }

    for _ in 0..50 {
        turtle.forward(SIZE / 2.5);
        turtle.left(1.0);
    }

    for _ in 0..30 {
        turtle.forward(SIZE / 3.0);
        turtle.left(1.8);
    }

    for _ in 0..10 {
        turtle.forward(SIZE / 1.5);
        turtle.left(1.8);
    }

    turtle.end_fill();
}

Head

Eye

Adding code to the main function

turtle.left(128.0);
turtle.forward(SIZE * 15.0);

draw_eye(&mut turtle);

Creating draw_eye function

fn draw_eye(turtle: &mut Turtle) {
    turtle.set_fill_color(EYE_COLOR);
    turtle.begin_fill();
    for _ in 0..90 {
        turtle.forward(SIZE / 3.0);
        turtle.right(4.0);
    }
    turtle.end_fill();
}

Eye

Highlights

Adding code to the main function

turtle.set_fill_color(BODY_COLOR);

turtle.left(175.0);
turtle.forward(SIZE * 43.0);

draw_right_highlight(&mut turtle);

turtle.right(18.0);
turtle.forward(SIZE * 37.0);
turtle.set_heading(180.0);

draw_middle_highlight(&mut turtle);

turtle.left(24.0);
turtle.forward(SIZE * 36.0);
turtle.set_heading(180.0);

draw_left_highlight(&mut turtle);

Creating highlight functions

fn draw_right_highlight(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..39 {
        turtle.forward(SIZE / 5.0);
        turtle.left(2.0);
    }

    turtle.forward(SIZE * 36.0);

    for _ in 0..90 {
        turtle.forward(SIZE / 2.5);
        turtle.left(2.0);
    }

    for _ in 0..42 {
        turtle.forward(SIZE);
        turtle.left(0.9);
    }

    for _ in 0..26 {
        turtle.forward(SIZE / 5.0);
        turtle.left(2.0);
    }

    turtle.end_fill();
}

fn draw_middle_highlight(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..40 {
        turtle.forward(SIZE / 4.0);
        turtle.left(2.0);
    }

    turtle.forward(SIZE * 47.0);
    turtle.left(8.5);

    for _ in 0..90 {
        turtle.forward(SIZE / 2.0);
        turtle.left(2.0);
    }
    turtle.forward(SIZE / 2.0);

    turtle.left(8.5);
    turtle.forward(SIZE * 47.0);

    for _ in 0..40 {
        turtle.left(2.0);
        turtle.forward(SIZE / 4.0);
    }

    turtle.end_fill();
}

fn draw_left_highlight(turtle: &mut Turtle) {
    turtle.begin_fill();

    for _ in 0..26 {
        turtle.forward(SIZE / 5.0);
        turtle.left(2.0);
    }

    for _ in 0..42 {
        turtle.forward(SIZE);
        turtle.left(0.9);
    }

    for _ in 0..90 {
        turtle.forward(SIZE / 2.5);
        turtle.left(2.0);
    }

    turtle.forward(SIZE * 36.0);

    for _ in 0..39 {
        turtle.forward(SIZE / 5.0);
        turtle.left(2.0);
    }

    turtle.end_fill();
}

Turtle

Main function

fn main() {
    let mut turtle = Turtle::new();
    turtle.set_speed(8);

    turtle.pen_up();
    turtle.set_x(-280.0);
    turtle.set_y(-90.0);

    draw_shell(&mut turtle);

    draw_tail(&mut turtle);

    turtle.pen_up();
    turtle.right(55.0);
    turtle.forward(SIZE * 10.0);
    turtle.right(55.0);

    // Back leg
    draw_leg(&mut turtle);

    turtle.right(86.5);
    turtle.forward(SIZE * 55.0);
    turtle.right(86.0);

    // Front leg
    draw_leg(&mut turtle);

    turtle.right(54.5);
    turtle.forward(SIZE * 8.0);

    draw_neck(&mut turtle);

    turtle.right(172.6);
    turtle.forward(SIZE * 40.0);
    turtle.right(110.0);

    draw_head(&mut turtle);

    turtle.left(128.0);
    turtle.forward(SIZE * 15.0);

    draw_eye(&mut turtle);

    turtle.set_fill_color(BODY_COLOR);

    turtle.left(175.0);
    turtle.forward(SIZE * 43.0);

    draw_right_highlight(&mut turtle);

    turtle.right(18.0);
    turtle.forward(SIZE * 37.0);
    turtle.set_heading(180.0);

    draw_middle_highlight(&mut turtle);

    turtle.left(24.0);
    turtle.forward(SIZE * 36.0);
    turtle.set_heading(180.0);

    draw_left_highlight(&mut turtle);
}

Result

Example