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