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terrapin.go
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/
terrapin.go
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package terrapin
import (
"image"
"image/color"
"math"
)
type Terrapin struct {
Image *image.RGBA
Pos Position
Orientation float64
Color color.Color
Pen bool
}
type Position struct {
X, Y float64
}
func NewTerrapin(i *image.RGBA, starting Position) (t *Terrapin) {
t = &Terrapin{
Image: i,
Pos: starting,
Orientation: 0.0,
Color: color.Black,
Pen: true,
}
return
}
func (t *Terrapin) Forward(dist float64) {
for i := 0; i < int(dist); i++ {
if t.Pen {
t.Image.Set(int(t.Pos.X), int(t.Pos.Y), t.Color)
}
x := 1.0 * math.Sin(t.Orientation)
y := 1.0 * -math.Cos(t.Orientation)
t.Pos = Position{t.Pos.X + x, t.Pos.Y + y}
}
}
func (t *Terrapin) Backward(dist float64) {
t.Forward(-dist)
}
func (t *Terrapin) Right(radians float64) {
t.Orientation += radians
}
func (t *Terrapin) Left(radians float64) {
t.Right(-radians)
}
func (t *Terrapin) PenUp() {
t.Pen = false
}
func (t *Terrapin) PenDown() {
t.Pen = true
}