dotSCAD/docs/lib3x-t2d.md

t2d

An implementation of Turtle Graphics with Fluent API. It moves on the xy plane. You can get the cooridinate [x, y] or angle of its current position.

Since: 2.1

Parameters

• t : The data of a turtle. t2d() with no arguments will return a turtle with the point [0, 0] and the angle 0.
• cmd : It accepts a string or a list of commands.
  • Given a string: "turn", "forward", "point" or "angle". If "turn" is provided, the angle parameter is required. If "forward" is provided, leng is required. "point" and "angle" are used to get respective data from a turtle.
  • Given a list: [[cmd1, value], [cmd2, value2], ...]. For example, [["forward", 10], ["turn", 120]] will forward a turtle 10mm and turn it 120 degrees.
• point : Set the position of a turtle.
• angle : Set the angle of a turtle if cmd is not provided. Turn a turtle if cmd is "turn".
• leng : Forward a turtle if cmd is "forward".

Examples

use <line2d.scad>
use <turtle/t2d.scad>

module turtle_spiral(t, times, side_leng, angle, width) {
    $fn = 24;
    if(times != 0) {
        t1 = t2d(t, "turn", angle = angle);
        t2 = t2d(t1, "forward", leng = side_leng);

        line2d(
            t2d(t, "point"),
            t2d(t2, "point"),
            width,
            p1Style = "CAP_ROUND", 
            p2Style =  "CAP_ROUND"
        );

        turtle_spiral(t2, times - 1, side_leng, angle, width);
    }

}

turtle_spiral(
    t2d(point = [0, 0], angle = 0), 
    times = 5, 
    side_leng = 10, 
    angle = 144, 
    width = 1
);

The code below creates the same drawing.

use <line2d.scad>
use <turtle/t2d.scad>

module turtle_spiral(t, times, side_leng, angle, width) {
	$fn = 24;
	if(times != 0) {
		t1 = t2d(t, [
			["turn", angle],
			["forward", side_leng]
		]);
		
		line2d(
			t2d(t, "point"),
			t2d(t1, "point"),
			width,
			p1Style = "CAP_ROUND", 
			p2Style =  "CAP_ROUND"
		);

		turtle_spiral(t1, times - 1, side_leng, angle, width);
	}
}

turtle_spiral(
	t2d(point = [0, 0], angle = 0), 
	times = 5, 
	side_leng = 10, 
	angle = 144, 
	width = 1
);	 

use <polyline_join.scad>
use <turtle/t2d.scad>

side_leng = 100;
min_leng = 4;
thickness = 0.5; 

sierpinski_triangle(
    t2d(point = [0, 0], angle = 0),
    side_leng, min_leng, thickness, $fn = 3
);

module triangle(t, side_leng, thickness) {    
    t2 = t2d(t, "forward", leng = side_leng);
    t3 = t2d(t2, [
        ["turn", 120],
        ["forward", side_leng]
    ]);

    polyline_join([for(turtle = [t, t2, t3, t]) t2d(turtle, "point")]) 
	    circle(thickness / 2);
}

module sierpinski_triangle(t, side_leng, min_leng, thickness) {
    triangle(t, side_leng, thickness);

    if(side_leng >= min_leng) { 
        half_leng = side_leng / 2;
        t2 = t2d(t, "forward", leng = half_leng); 
        t3 = t2d(t, [
            ["turn", 60],
            ["forward", half_leng],
            ["turn", -60]
        ]);

        for(turtle = [t, t2, t3]) {
            sierpinski_triangle(turtle, half_leng, min_leng, thickness);
        }
    }
}