arcLeft

Category:Turtle

arcLeft(angle, radius)

Category: Turtle

Moves the turtle forward and to the left in a smooth, circular arc.

The turtle is not limited to only moving in a straight line. arcLeft(angle,radius) moves the turtle counterclockwise along an angle degree arc of a radius sized circle. The center of the circle is radius pixels to the left of the starting turtle position and direction.

Examples

// Draw a quarter circle counterclockwise.
arcLeft(90, 25);

Example: One Ring to Rule Them All Draw a full circle counterclockwise.

// Draw a full circle counterclockwise.
penColor("gold");
penWidth(15);
arcLeft(360, 50);

Example: Negative Angle arcLeft always moves the turtle counterclockwise. For a negative angle the turtle moves (360+angle) degrees.

// arcLeft always moves the turtle counterclockwise. 
// For a negative angle the turtle moves (360+angle) degrees.
arcLeft(-45, 100);

Example: Spiral Spiral into the center of a circle.

// Spiral into the center of a circle.
for (var radius=50; radius>0; radius=radius-5) {
  arcLeft(180, radius);
}

Syntax

arcLeft(angle, radius);

Parameters

Name	Type	Required?	Description
angle	number	Yes	The angle degree arc to move the turtle counterclockwise in a circle.
radius	number	Yes	The radius of the circle that is placed left of the turtle. radius must be >= 0.

Returns

No return value. Moves turtle only.

Tips

Use penUp() before calling arcLeft() to have the turtle not draw as it moves.
You can specify a radius of 0, which makes arcLeft() act the same as turnLeft().
Use alternating with arcRight() to make wavy lines.

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