firka/flutter
3
0
Fork 1
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add Matrix::LookAt (flutter/engine#37361)

Browse Source
This commit is contained in:
Brandon DeRosier
2022-11-06 16:08:52 -08:00
committed by GitHub
parent 24adff54d8
commit 0bd81de8a1
2 changed files with 63 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
engine/src/flutter/impeller/geometry/geometry_unittests.cc
View File

@@ -424,6 +424,52 @@ TEST(GeometryTest, MatrixIsAligned) {
}
}
TEST(GeometryTest, MatrixLookAt) {
{
auto m = Matrix::MakeLookAt(Vector3(0, 0, -1), Vector3(0, 0, 1),
Vector3(0, 1, 0));
auto expected = Matrix{
1, 0, 0, 0, //
0, 1, 0, 0, //
0, 0, 1, 0, //
0, 0, 1, 1, //
};
ASSERT_MATRIX_NEAR(m, expected);
}
// Sideways tilt.
{
auto m = Matrix::MakeLookAt(Vector3(0, 0, -1), Vector3(0, 0, 1),
Vector3(1, 1, 0).Normalize());
// clang-format off
auto expected = Matrix{
k1OverSqrt2, k1OverSqrt2, 0, 0,
-k1OverSqrt2, k1OverSqrt2, 0, 0,
0, 0, 1, 0,
0, 0, 1, 1,
};
// clang-format on
ASSERT_MATRIX_NEAR(m, expected);
}
// Half way between +x and -y, yaw 90
{
auto m =
Matrix::MakeLookAt(Vector3(), Vector3(10, -10, 0), Vector3(0, 0, -1));
// clang-format off
auto expected = Matrix{
-k1OverSqrt2, 0, k1OverSqrt2, 0,
-k1OverSqrt2, 0, -k1OverSqrt2, 0,
0, -1, 0, 0,
0, 0, 0, 1,
};
// clang-format on
ASSERT_MATRIX_NEAR(m, expected);
}
}
TEST(GeometryTest, QuaternionLerp) {
auto q1 = Quaternion{{0.0, 0.0, 1.0}, 0.0};
auto q2 = Quaternion{{0.0, 0.0, 1.0}, kPiOver4};

17
engine/src/flutter/impeller/geometry/matrix.h
View File

@@ -435,6 +435,23 @@ struct Matrix {
return MakePerspective(fov_y, static_cast<Scalar>(size.width) / size.height,
z_near, z_far);
}
static constexpr Matrix MakeLookAt(Vector3 position,
Vector3 target,
Vector3 up) {
Vector3 forward = (target - position).Normalize();
Vector3 right = up.Cross(forward);
up = forward.Cross(right);
// clang-format off
return {
right.x, up.x, forward.x, 0.0f,
right.y, up.y, forward.y, 0.0f,
right.z, up.z, forward.z, 0.0f,
-right.Dot(position), -up.Dot(position), -forward.Dot(position), 1.0f
};
// clang-format on
}
};
static_assert(sizeof(struct Matrix) == sizeof(Scalar) * 16,