38 lines
883 B
Go
38 lines
883 B
Go
|
package clockface
|
||
|
|
|
||
|
|
import (
|
||
|
|
"math"
|
||
|
|
"time"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Point represents a two-dimentional Cartesian coordinate
|
||
|
|
type Point struct {
|
||
|
|
X float64
|
||
|
|
Y float64
|
||
|
|
}
|
||
|
|
|
||
|
|
// SecondHand is the unit vector of the second hand of an analogue clock at the time `t` represented as a Point
|
||
|
|
func SecondHand(t time.Time) Point {
|
||
|
|
p := secondHandPoint(t)
|
||
|
|
p = Point{p.X * 90, p.Y * 90} // scale
|
||
|
|
p = Point{p.X, -p.Y} // flip
|
||
|
|
p = Point{p.X + 150, p.Y + 150} // translate
|
||
|
|
return p
|
||
|
|
}
|
||
|
|
|
||
|
|
func secondsInRadians(t time.Time) float64 {
|
||
|
|
// XXX:Wanted 3.141592653589793 radians, but got 3.1415926535897936
|
||
|
|
// return float64(t.Second()) * (math.Pi / 30)
|
||
|
|
|
||
|
|
return math.Pi / (30 / float64(t.Second()))
|
||
|
|
}
|
||
|
|
|
||
|
|
func secondHandPoint(t time.Time) Point {
|
||
|
|
angle := secondsInRadians(t)
|
||
|
|
x := math.Sin(angle)
|
||
|
|
y := math.Cos(angle)
|
||
|
|
|
||
|
|
// XXX: Wanted {0 -1} Point, but got {1.2246467991473515e-16 -1}
|
||
|
|
return Point{x, y}
|
||
|
|
}
|