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[Impeller] Simplify calculation of Matrix::GetMaxBasisXY() (flutter/engine#51664)

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Since 2D coordinates have a `Z` value of `0.0`, they don't need to include the Z basis vector in calculating a scale.
This commit is contained in:
Jim Graham
2024-03-26 12:03:04 -07:00
committed by GitHub
parent df1c571aec
commit 118bfc65c4
3 changed files with 16 additions and 9 deletions
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12
engine/src/flutter/impeller/geometry/geometry_unittests.cc
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@@ -352,6 +352,18 @@ TEST(GeometryTest, MatrixGetMaxBasisLengthXY) {
auto m = Matrix::MakeScale({-3, 4, 7});
ASSERT_EQ(m.GetMaxBasisLengthXY(), 4);
}
{
// clang-format off
auto m = Matrix::MakeColumn(
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
4.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
);
// clang-format on
ASSERT_EQ(m.GetMaxBasisLengthXY(), 1.0f);
}
}
TEST(GeometryTest, MatrixMakeOrthographic) {

8
engine/src/flutter/impeller/geometry/matrix.cc
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@@ -202,14 +202,6 @@ Scalar Matrix::GetMaxBasisLength() const {
return std::sqrt(max);
}
Scalar Matrix::GetMaxBasisLengthXY() const {
Scalar max = 0;
for (int i = 0; i < 3; i++) {
max = std::max(max, e[i][0] * e[i][0] + e[i][1] * e[i][1]);
}
return std::sqrt(max);
}
/*
* Adapted for Impeller from Graphics Gems:
* http://www.realtimerendering.com/resources/GraphicsGems/gemsii/unmatrix.c

5
engine/src/flutter/impeller/geometry/matrix.h
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@@ -292,7 +292,10 @@ struct Matrix {
Scalar GetMaxBasisLength() const;
Scalar GetMaxBasisLengthXY() const;
constexpr Scalar GetMaxBasisLengthXY() const {
return std::sqrt(std::max(e[0][0] * e[0][0] + e[0][1] * e[0][1],
e[1][0] * e[1][0] + e[1][1] * e[1][1]));
}
constexpr Vector3 GetBasisX() const { return Vector3(m[0], m[1], m[2]); }