Function TestCapIntersectsCell

s2/cap_test.go:515–584

(t *testing.T)

}

func TestCapIntersectsCell(t *testing.T) {
	faceRadius := math.Atan(math.Sqrt2)
	for face := range 6 {
		// The cell consisting of the entire face.
		rootCell := CellFromCellID(CellIDFromFace(face))

		// A leaf cell at the midpoint of the v=1 edge.
		edgeCell := CellFromPoint(Point{faceUVToXYZ(face, 0, 1-epsilon)})

		// A leaf cell at the u=1, v=1 corner
		cornerCell := CellFromPoint(Point{faceUVToXYZ(face, 1-epsilon, 1-epsilon)})

		// Quick check for full and empty caps.
		if emptyCap.IntersectsCell(rootCell) {
			t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", emptyCap, rootCell, true, false)
		}

		// Check intersections with the bounding caps of the leaf cells that are adjacent to
		// cornerCell along the Hilbert curve.  Because this corner is at (u=1,v=1), the curve
		// stays locally within the same cube face.
		first := cornerCell.id.Advance(-3)
		last := cornerCell.id.Advance(4)
		for id := first; id < last; id = id.Next() {
			c := CellFromCellID(id).CapBound()
			if got, want := c.IntersectsCell(cornerCell), id.immediateParent().Contains(cornerCell.id); got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", c, cornerCell, got, want)
			}
		}

		antiFace := (face + 3) % 6
		for capFace := range 6 {
			// A cap that barely contains all of capFace.
			center := unitNorm(capFace)
			covering := CapFromCenterAngle(center, s1.Angle(faceRadius+epsilon))
			if got, want := covering.IntersectsCell(rootCell), capFace != antiFace; got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", covering, rootCell, got, want)
			}
			if got, want := covering.IntersectsCell(edgeCell), covering.ContainsCell(edgeCell); got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", covering, edgeCell, got, want)
			}
			if got, want := covering.IntersectsCell(cornerCell), center.Dot(cornerCell.id.Point().Vector) > 0; got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", covering, cornerCell, got, want)
			}

			// A cap that barely intersects the edges of capFace.
			bulging := CapFromCenterAngle(center, s1.Angle(math.Pi/4+epsilon))
			if got, want := bulging.IntersectsCell(rootCell), capFace != antiFace; got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", bulging, rootCell, got, want)
			}
			if got, want := bulging.IntersectsCell(edgeCell), center.Dot(edgeCell.id.Point().Vector) > 0.1; got != want {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", bulging, edgeCell, got, want)
			}
			if bulging.IntersectsCell(cornerCell) {
				t.Errorf("Cap(%v).IntersectsCell(%v) = %t; want = %t", bulging, cornerCell, true, false)
			}

			// A singleton cap.
			singleton := CapFromCenterAngle(center, 0)