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regularPointsForFrame: Allocate memory in one go #215

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Merged
merged 4 commits into from
Sep 17, 2025
Merged

regularPointsForFrame: Allocate memory in one go #215

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4ccba84
regularPointsForFrame: Allocate memory in one go
fx408 Sep 13, 2025
4fd6319
Correct the benchmark
fx408 Sep 17, 2025
165b48d
Keep the code style
fx408 Sep 17, 2025
49ad1f5
Use for...range instead of for
fx408 Sep 17, 2025
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6 changes: 3 additions & 3 deletions s2/point.go
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Original file line number Diff line number Diff line change
Expand Up @@ -160,12 +160,12 @@ func regularPointsForFrame(frame matrix3x3, radius s1.Angle, numVertices int) []
z := math.Cos(radius.Radians())
r := math.Sin(radius.Radians())
radianStep := 2 * math.Pi / float64(numVertices)
var vertices []Point
var vertices = make([]Point, numVertices)

for i := 0; i < numVertices; i++ {
for i := range vertices {
angle := float64(i) * radianStep
p := Point{r3.Vector{X: r * math.Cos(angle), Y: r * math.Sin(angle), Z: z}}
vertices = append(vertices, Point{fromFrame(frame, p).Normalize()})
vertices[i] = Point{fromFrame(frame, p).Normalize()}
}

return vertices
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10 changes: 10 additions & 0 deletions s2/point_test.go
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Expand Up @@ -458,3 +458,13 @@ func TestPointEnsureNormalizable(t *testing.T) {
}
}
}

func BenchmarkPointRegularPoints(b *testing.B) {
center := PointFromLatLng(LatLngFromDegrees(80, 135))
radius := s1.Degree * 20

b.ReportAllocs()
for i := 0; i < b.N; i++ {
regularPoints(center, radius, 8)
}
}