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matrix_decomposition.cc
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matrix_decomposition.cc
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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "flutter/flow/matrix_decomposition.h"
namespace flow {
static inline SkVector3 SkVector3Combine(const SkVector3& a,
float a_scale,
const SkVector3& b,
float b_scale) {
return {
a_scale * a.fX + b_scale * b.fX, //
a_scale * a.fY + b_scale * b.fY, //
a_scale * a.fZ + b_scale * b.fZ, //
};
}
static inline SkVector3 SkVector3Cross(const SkVector3& a, const SkVector3& b) {
return {
(a.fY * b.fZ) - (a.fZ * b.fY), //
(a.fZ * b.fX) - (a.fX * b.fZ), //
(a.fX * b.fY) - (a.fY * b.fX) //
};
}
MatrixDecomposition::MatrixDecomposition(const SkMatrix& matrix)
: MatrixDecomposition(SkMatrix44{matrix}) {}
MatrixDecomposition::MatrixDecomposition(SkMatrix44 matrix) : valid_(false) {
if (matrix.get(3, 3) == 0) {
return;
}
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
matrix.set(j, i, matrix.get(j, i) / matrix.get(3, 3));
}
}
SkMatrix44 perpective_matrix = matrix;
for (int i = 0; i < 3; i++) {
perpective_matrix.set(3, i, 0.0);
}
perpective_matrix.set(3, 3, 1.0);
if (perpective_matrix.determinant() == 0.0) {
return;
}
if (matrix.get(3, 0) != 0.0 || matrix.get(3, 1) != 0.0 ||
matrix.get(3, 2) != 0.0) {
const SkVector4 right_hand_side(matrix.get(3, 0), matrix.get(3, 1),
matrix.get(3, 2), matrix.get(3, 3));
SkMatrix44 inverted_transposed(
SkMatrix44::Uninitialized_Constructor::kUninitialized_Constructor);
if (!perpective_matrix.invert(&inverted_transposed)) {
return;
}
inverted_transposed.transpose();
perspective_ = inverted_transposed * right_hand_side;
matrix.set(3, 0, 0);
matrix.set(3, 1, 0);
matrix.set(3, 2, 0);
matrix.set(3, 3, 1);
}
translation_ = {matrix.get(0, 3), matrix.get(1, 3), matrix.get(2, 3)};
matrix.set(0, 3, 0.0);
matrix.set(1, 3, 0.0);
matrix.set(2, 3, 0.0);
SkVector3 row[3];
for (int i = 0; i < 3; i++) {
row[i].set(matrix.get(0, i), matrix.get(1, i), matrix.get(2, i));
}
scale_.fX = row[0].length();
row[0].normalize();
shear_.fX = row[0].dot(row[1]);
row[1] = SkVector3Combine(row[1], 1.0, row[0], -shear_.fX);
scale_.fY = row[1].length();
row[1].normalize();
shear_.fX /= scale_.fY;
shear_.fY = row[0].dot(row[2]);
row[2] = SkVector3Combine(row[2], 1.0, row[0], -shear_.fY);
shear_.fZ = row[1].dot(row[2]);
row[2] = SkVector3Combine(row[2], 1.0, row[1], -shear_.fZ);
scale_.fZ = row[2].length();
row[2].normalize();
shear_.fY /= scale_.fZ;
shear_.fZ /= scale_.fZ;
if (row[0].dot(SkVector3Cross(row[1], row[2])) < 0) {
scale_.fX *= -1;
scale_.fY *= -1;
scale_.fZ *= -1;
for (int i = 0; i < 3; i++) {
row[i].fX *= -1;
row[i].fY *= -1;
row[i].fZ *= -1;
}
}
rotation_.set(0.5 * sqrt(fmax(1.0 + row[0].fX - row[1].fY - row[2].fZ, 0.0)),
0.5 * sqrt(fmax(1.0 - row[0].fX + row[1].fY - row[2].fZ, 0.0)),
0.5 * sqrt(fmax(1.0 - row[0].fX - row[1].fY + row[2].fZ, 0.0)),
0.5 * sqrt(fmax(1.0 + row[0].fX + row[1].fY + row[2].fZ, 0.0)));
if (row[2].fY > row[1].fZ) {
rotation_.fData[0] = -rotation_.fData[0];
}
if (row[0].fZ > row[2].fX) {
rotation_.fData[1] = -rotation_.fData[1];
}
if (row[1].fX > row[0].fY) {
rotation_.fData[2] = -rotation_.fData[2];
}
valid_ = true;
}
MatrixDecomposition::~MatrixDecomposition() = default;
bool MatrixDecomposition::IsValid() const {
return valid_;
}
} // namespace flow