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Angle calculations between two vectors

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This commit is contained in:
Fraser Graham 2013-09-21 18:34:53 -07:00
parent 1610816e8a
commit 70c53c6e9a
2 changed files with 38 additions and 9 deletions
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41
govector_test.go
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@ -119,16 +119,39 @@ func TestIntersection(t *testing.T) {
t.Errorf("Intersection Error") t.Errorf("Intersection Error")
} }
p1 = Point2d{20, 5} p1 = Point2d{20, 5}
p2 = Point2d{5, 0} p2 = Point2d{5, 0}
v1 = Vector2d{10, 0} v1 = Vector2d{10, 0}
v2 = Vector2d{0, 10} v2 = Vector2d{0, 10}
i, p = Intersection(p1, p2, v1, v2) i, p = Intersection(p1, p2, v1, v2)
fmt.Printf("%v %v\n", i, p) fmt.Printf("%v %v\n", i, p)
if i { if i {
t.Errorf("Intersection Error") t.Errorf("Intersection Error")
} }
}
func TestAngle(t *testing.T) {
v1 := Vector2d{10, 0}
v2 := Vector2d{0, 10}
a := Angle(v2, v1)
fmt.Printf("%v %v %f\n", v1, v2, a*rad2deg)
if math.Abs(a-math.Pi/2) > epsilon {
t.Errorf("Angle Error")
}
v1 = Vector2d{5, 0}
v2 = Vector2d{10, 10}
a = Angle(v1, v2)
fmt.Printf("%v %v %f\n", v1, v2, a*rad2deg)
if math.Abs(a-math.Pi/4) > epsilon {
t.Errorf("Angle Error")
}
} }

6
vectorpoint.go
View File

@ -22,6 +22,7 @@ type Point2d struct {
} }
const epsilon = 1e-7 const epsilon = 1e-7
const rad2deg = 180 / math.Pi
func (p1 Point2d) Sub(p2 Point2d) Vector2d { func (p1 Point2d) Sub(p2 Point2d) Vector2d {
return Vector2d{p1.X - p2.X, p1.Y - p2.Y} return Vector2d{p1.X - p2.X, p1.Y - p2.Y}
@ -80,3 +81,8 @@ func Move(d1, d2 Point2d, velocity float64, timeDelta float64) Point2d {
func Distance(p1, p2 Point2d) float64 { func Distance(p1, p2 Point2d) float64 {
return p1.Sub(p2).Mag() return p1.Sub(p2).Mag()
} }
func Angle(v1, v2 Vector2d) float64 {
x := (v1.Dot(v2) / (v1.Mag() * v2.Mag()))
return math.Acos(x)
}