README
¶
go-turtle
Turtle graphics in Go.
A couple of small showcase scripts are in the samples folder.
Moving around:
A conveniently 4K shaped image:
Turtle
A minimal Turtle agent, moving on a cartesian plane.
The orientation is in degrees.
Right rotates clockwise, Left counter-clockwise.
Use it to simulate the movements of the turtle without the drawing overhead.
// create a new turtle
t := turtle.New()
// move it just like you expect
t.Forward(5)
t.Left(45)
t.Forward(5)
t.Right(45)
t.Backward(5)
// get the X, Y, Deg data as needed
fmt.Println(t.X, t.Y, t.Deg)
// 3.5355339059327378 3.5355339059327373 0
// teleport around
t.SetPos(4, 4)
t.SetHeading(120)
// vaguely nice printing
fmt.Println("T:", t)
// T: ( 4.0000, 4.0000) ^ 120.0000
TurtleDraw
Has the same interface of Turtle, but draws.
Each TurtleDraw is attached to a World.
Create a new world to draw in:
w := turtle.NewWorld(900, 600)
When creating a World with NewWorld,
an uniform image of the requested size (width, height)
with SoftBlack background is generated.
An existing image can be used as base:
img := image.NewRGBA(image.Rect(0, 0, 900, 600))
draw.Draw(img, img.Bounds(), &image.Uniform{turtle.Cyan}, image.Point{0, 0}, draw.Src)
wi := turtle.NewWorldImage(img)
Create a TurtleDraw attached to the World:
// create a turtle attached to w
td := turtle.NewTurtleDraw(w)
// position/orientation
td.SetPos(100, 300)
td.SetHeading(turtle.North + 80)
// line style
td.SetColor(turtle.Blue)
td.SetSize(4)
// start drawing
td.PenDown()
// same interface as Turtle
td.Forward(100)
td.Left(160)
td.Forward(100)
Save the current image:
err := w.SaveImage("world.png")
if err != nil {
fmt.Println("Could not save the image: ", err)
}
Close the world (there are two open internal channels).
w.Close()
// this is an error: the turtle tries to send the line
// to the world input channel that has been closed
// td.Forward(50)
You can create as many turtles as you want. When drawing, a turtle sends the line to the world on a channel and blocks until it is done.
Constants
A few standard colors:
Black = color.RGBA{0, 0, 0, 255}
SoftBlack = color.RGBA{10, 10, 10, 255}
White = color.RGBA{255, 255, 255, 255}
Red = color.RGBA{255, 0, 0, 255}
Green = color.RGBA{0, 255, 0, 255}
Blue = color.RGBA{0, 0, 255, 255}
Cyan = color.RGBA{0, 255, 255, 255}
Magenta = color.RGBA{255, 0, 255, 255}
Yellow = color.RGBA{255, 255, 0, 255}
DarkOrange = color.RGBA{150, 75, 0, 255} // It's just so warm and relaxing
Cardinal directions:
East = 0.0
North = 90.0
West = 180.0
South = 270.0
Implementation notes
Note on float64
A lot of inputs to the API are actually float64, so when using a variable
instead of an untyped const the compiler will complain if the var is int.
So this works as the var has type float:
segLen := 150.0
td.Forward(segLen)
and this does not:
segLen := 150
td.Forward(segLen)
// cannot use segLen (variable of type int) as float64 value
// in argument to td.Forward (compile)
This works magically because in Go constants are neat.
td.Forward(150)
Drawing pixels
When drawing points of odd size, the square is centered on the position.
When drawing points of even size, the square is shifted to the top and right.
The red points are drawn with y=0, along the bottom border of the image.
To draw a single point, just call forward with 0 dist:
td.Forward(0)
Channels and line drawing
The world draws the Line it receives on the DrawLineCh channel,
so you can technically draw a line directly with that
skipping the turtles altogether,
and everything should work.
TODO - Ideas
- Hilbert sample!
- More colors!
Contributing
This was a side project to another one I was doing to learn Go, so all improvements and suggestions for a better code are welcome.
Documentation
¶
Index ¶
Constants ¶
const ( East = 0.0 North = 90.0 West = 180.0 South = 270.0 )
Standard directions.
Variables ¶
var ( Black = color.RGBA{0, 0, 0, 255} SoftBlack = color.RGBA{10, 10, 10, 255} White = color.RGBA{255, 255, 255, 255} Red = color.RGBA{255, 0, 0, 255} Green = color.RGBA{0, 255, 0, 255} Blue = color.RGBA{0, 0, 255, 255} Cyan = color.RGBA{0, 255, 255, 255} Magenta = color.RGBA{255, 0, 255, 255} Yellow = color.RGBA{255, 255, 0, 255} // I just love this one DarkOrange = color.RGBA{150, 75, 0, 255} )
Standard colors.
Functions ¶
Types ¶
type Pen ¶
type Pen struct {
Color color.Color // Line color.
Size int // Line width.
On bool // State of the Pen.
}
A simple Pen.
type Turtle ¶
A minimal Turtle agent, moving on a cartesian plane.
type TurtleDraw ¶
type TurtleDraw struct {
Turtle // Turtle agent to move around.
Pen // Pen used when drawing.
W *World // World to draw on.
}
A drawing Turtle.
func NewTurtleDraw ¶
func NewTurtleDraw(w *World) *TurtleDraw
Create a new TurtleDraw, attached to the World w.
func (*TurtleDraw) Backward ¶
func (td *TurtleDraw) Backward(dist float64)
Move the turtle backward and draw the line if the Pen is On.
func (*TurtleDraw) Forward ¶
func (td *TurtleDraw) Forward(dist float64)
Move the turtle forward and draw the line if the Pen is On.
func (*TurtleDraw) SetPos ¶
func (td *TurtleDraw) SetPos(x, y float64)
Teleport the Turtle to (x, y) and draw the line if the Pen is On.
type World ¶
type World struct {
Image *image.RGBA
Width, Height int
DrawLineCh chan Line
// contains filtered or unexported fields
}
A world to draw on.
func NewWorldImage ¶
Create a new World attached to the Image img, and start listening on w.DrawLineCh for lines to draw.
Source Files
Directories