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Add utility to check if a Matrix is aligned (flutter/engine#35951)

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This commit is contained in:
Brandon DeRosier 2022-09-06 16:58:53 -07:00 committed by GitHub
parent d540929cef
commit ee87ce6517
3 changed files with 45 additions and 1 deletions
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14
engine/src/flutter/impeller/geometry/geometry_unittests.cc
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@ -351,6 +351,20 @@ TEST(GeometryTest, MatrixGetDirectionScale) {
}
}
TEST(GeometryTest, MatrixIsAligned) {
{
auto m = Matrix::MakeTranslation({1, 2, 3});
bool result = m.IsAligned();
ASSERT_TRUE(result);
}
{
auto m = Matrix::MakeRotationZ(Degrees{123});
bool result = m.IsAligned();
ASSERT_FALSE(result);
}
}
TEST(GeometryTest, QuaternionLerp) {
auto q1 = Quaternion{{0.0, 0.0, 1.0}, 0.0};
auto q2 = Quaternion{{0.0, 0.0, 1.0}, kPiOver4};

25
engine/src/flutter/impeller/geometry/matrix.h
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@ -258,6 +258,31 @@ struct Matrix {
m[9] == 0 && m[10] == 1 && m[11] == 0 && m[14] == 0 && m[15] == 1);
}
constexpr bool IsAligned(Scalar tolerance = 0) const {
int v[] = {!ScalarNearlyZero(m[0], tolerance), //
!ScalarNearlyZero(m[1], tolerance), //
!ScalarNearlyZero(m[2], tolerance), //
!ScalarNearlyZero(m[4], tolerance), //
!ScalarNearlyZero(m[5], tolerance), //
!ScalarNearlyZero(m[6], tolerance), //
!ScalarNearlyZero(m[8], tolerance), //
!ScalarNearlyZero(m[9], tolerance), //
!ScalarNearlyZero(m[10], tolerance)};
// Check if all three basis vectors are aligned to an axis.
if (v[0] + v[1] + v[2] != 1 || //
v[3] + v[4] + v[5] != 1 || //
v[6] + v[7] + v[8] != 1) {
return false;
}
// Ensure that none of the basis vectors overlap.
if (v[0] + v[3] + v[6] != 1 || //
v[1] + v[4] + v[7] != 1 || //
v[2] + v[5] + v[8] != 1) {
return false;
}
return true;
}
constexpr bool IsIdentity() const {
return (
// clang-format off

7
engine/src/flutter/impeller/geometry/scalar.h
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@ -19,10 +19,15 @@ constexpr T Absolute(const T& val) {
return val >= T{} ? val : -val;
}
constexpr inline bool ScalarNearlyZero(Scalar x,
Scalar tolerance = kEhCloseEnough) {
return Absolute(x) <= tolerance;
}
constexpr inline bool ScalarNearlyEqual(Scalar x,
Scalar y,
Scalar tolerance = kEhCloseEnough) {
return Absolute(x - y) <= tolerance;
return ScalarNearlyZero(x - y, tolerance);
}
struct Degrees;