The index package provides utilities, such as Color and Point, that are useful in the rest of the libraries.
In this section we just cover the most important uses. You should see the index for details.
// You definitely want doodle.core import doodle.core._ // You probably also want extension methods import doodle.syntax.all._
The Angle type represents an angle, as the name suggests.
Most of the time you'll create
Angles using the extension methods shown below. Degrees and radians should be familiar, but turns may not be. One turn corresponds to a full circle (i.e. 360 degrees), so using turns in a convenient way to represent simple fractions or multiples of circles.
45.degrees 1.radians 0.5.turns // One turn is a full circle, so this is half a circle
There are various methods to perform arithmetic on angles. Here are some examples. See the Angle for a complete list.
(45.degrees + 45.degrees) < 180.degrees // res3: Boolean = true (45.degrees * 2) < 90.degrees // res4: Boolean = false 180.degrees - 0.5.turns // res5: Angle = Angle(0.0)
Other useful methods are calculating the sine and cosine of an angle, and normalizing an angle to between zero and 360 degrees.
0.5.turns.sin // res6: Double = 1.2246467991473532E-16 0.5.turns.cos // res7: Double = -1.0 2.turns.normalize == 1.turns // res8: Boolean = true
Working with Color is something that most images will do. There are two representations of color used in Doodle:
- hue, saturation, and lightness (HSL); and
- red, green, and blue (RGB).
The HSL representation is easier to work with, while the RGB representation is how colors are actually generated by computer screens. All colors also have an alpha value, which determines transparency. Various constructors allow creating colors
Color.hsl(0.degrees, 1.0, 0.5) // a vibrant red Color.hsla(0.degrees, 1.0, 0.5, 0.5) // set the alpha to 0.5 (half transparent) Color.rgb(0, 0, 255) // pure blue Color.rgb(0.uByte, 0.uByte, 255.uByte) // Using the UnsignedByte type Color.rgba(0, 0, 255, 0.5) // Setting alpha Color.rgba(0.uByte, 0.uByte, 255.uByte, 0.5.normalized) // Setting alpha
On the Color all the standard CSS colors are defined. Here are a few examples.
Color.steelBlue // Not to be confused with blue steel Color.beige Color.limeGreen
There are many methods to modify colors, such as
desaturate, and so on. See the Color for full details.
A Point represents a location in the 2-D plane. We can construct points from cartesian (xy-coordinates) or polar (radius and angle) coordinates as shown below.
Point(1.0, 1.0) // cartesian coordinates // res18: Point = Cartesian(x = 1.0, y = 1.0) // cartesian coordinates Point(1.0, 90.degrees) // polar coordinates // res19: Point = Polar(r = 1.0, angle = Angle(1.5707963267948966))
No matter how we construct a
Point we can still access x- and y-coordinates or radius and angle.
val pt1 = Point(1.0, 0.0) // pt1: Point = Cartesian(x = 1.0, y = 0.0) pt1.x // res20: Double = 1.0 pt1.y // res21: Double = 0.0 pt1.r // res22: Double = 1.0 pt1.angle // res23: Angle = Angle(0.0)
A Transform, in Doodle, represents an affine transform in two-dimensions. The easiest way to create a
Transform is via the methods on the Transform. Here are some examples.
Transform.scale(5.0, -2.0) Transform.rotate(90.degrees) Transform.translate(10, 10)
Transform can be applied to a
Point to transform that point.
Transform.scale(5.0, -2.0)(Point(1,1)) // res27: Point = Cartesian(x = 5.0, y = -2.0) Transform.rotate(90.degrees)(Point(1,1)) // res28: Point = Cartesian(x = -0.9999999999999999, y = 1.0) Transform.translate(10, 10)(Point(1,1)) // res29: Point = Cartesian(x = 11.0, y = 11.0)
Transforms can be composed together using the
Transform.scale(5.0, -2.0).andThen(Transform.translate(10, 10))(Point(1,1)) // res30: Point = Cartesian(x = 15.0, y = 8.0) Transform.scale(5.0, -2.0).translate(10, 10)(Point(1,1)) // Shorter version // res31: Point = Cartesian(x = 15.0, y = 8.0)
A Vec represents a two-dimensional vector. You can construct
Vecs from cartesian (xy-coordinates) or polar (length and angle) coordinates, just like
Vec(0, 1) // res32: Vec = Vec(x = 0.0, y = 1.0) Vec(1, 90.degrees) // res33: Vec = Vec(x = 6.123233995736766E-17, y = 1.0)