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spatial/r3: rework test for RotationFromQuat

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This commit is contained in:
Vladimir Chalupecky
2022-02-24 22:09:56 +01:00
committed by Vladimír Chalupecký
parent 8e43cfd19a
commit f4e711476a
1 changed files with 26 additions and 21 deletions
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47
spatial/r3/mat_test.go
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@@ -189,30 +189,35 @@ func TestOuter(t *testing.T) {
}
func TestRotationFromQuat(t *testing.T) {
const tol = 1e-11
const tol = 1e-14
rnd := rand.New(rand.NewSource(1))
var backing [9]float64 // reuse memory.
for tc := 0; tc < 20; tc++ {
q := quat.Number{Real: rnd.Float64(), Imag: rnd.Float64(), Jmag: rnd.Float64(), Kmag: rnd.Float64()}
qabs := quat.Abs(q)
q = quat.Scale(1/qabs, q)
m := NewMat(backing[:])
m.RotationFromQuat(q)
w, x, y, z := q.Real, q.Imag, q.Jmag, q.Kmag
x2, y2, z2 := x*x, y*y, z*z
norm := math.Sqrt(w*w + x2 + y2 + z2)
_ = norm
expect := NewMat([]float64{ // From https://en.wikipedia.org/wiki/Rotation_matrix#Quaternion
1 - 2*y2 - 2*z2, 2*x*y - 2*z*w, 2*x*z + 2*y*w,
2*x*y + 2*z*w, 1 - 2*x2 - 2*z2, 2*y*z - 2*x*w,
2*x*z - 2*y*w, 2*y*z + 2*x*w, 1 - 2*x2 - 2*y2,
})
if !mat.EqualApprox(m, expect, tol) {
t.Errorf("Out of tolerance.")
// Generate a random unit quaternion.
q := quat.Number{Real: rnd.NormFloat64(), Imag: rnd.NormFloat64(), Jmag: rnd.NormFloat64(), Kmag: rnd.NormFloat64()}
q = quat.Scale(1/quat.Abs(q), q)
// Convert it to a rotation matrix R.
var r Mat
r.RotationFromQuat(q)
// Check that the matrix has the determinant approximately equal to 1.
diff := math.Abs(r.Det() - 1)
if diff > tol {
t.Errorf("case %d: unexpected determinant of R; got=%f, want=1 (diff=%v)", tc, r.Det(), diff)
continue
}
det := m.Det()
if math.Abs(det-1) > tol {
t.Errorf("determinant expected to be 1. got %f", det)
// Generate a random point.
v := Vec{X: rnd.NormFloat64(), Y: rnd.NormFloat64(), Z: rnd.NormFloat64()}
// Rotate it using the formula q*v*conj(q).
want := Rotation(q).Rotate(v)
// Rotate it using the rotation matrix R.
got := r.MulVec(v)
// Check that |got-want| is small.
diff = Norm(Sub(got, want))
if diff > tol {
t.Errorf("case %d: unexpected result; got=%f, want=%f, (diff=%v)", tc, got, want, diff)
}
}
}