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filament/libs/math/include/math/mat2.h

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/*
* Copyright 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef MATH_MAT2_H_
#define MATH_MAT2_H_
#include <math/TMatHelpers.h>
#include <math/vec2.h>
#include <stdint.h>
#include <sys/types.h>
#define PURE __attribute__((pure))
namespace math {
// -------------------------------------------------------------------------------------
namespace details {
/**
* A 2x2 column-major matrix class.
*
* Conceptually a 2x2 matrix is a an array of 2 column vec2:
*
* mat2 m =
* \f$
* \left(
* \begin{array}{cc}
* m[0] & m[1] \\
* \end{array}
* \right)
* \f$
* =
* \f$
* \left(
* \begin{array}{cc}
* m[0][0] & m[1][0] \\
* m[0][1] & m[1][1] \\
* \end{array}
* \right)
* \f$
* =
* \f$
* \left(
* \begin{array}{cc}
* m(0,0) & m(0,1) \\
* m(1,0) & m(1,1) \\
* \end{array}
* \right)
* \f$
*
* m[n] is the \f$ n^{th} \f$ column of the matrix and is a vec2.
*
*/
template <typename T>
class MATH_EMPTY_BASES TMat22 :
public TVecUnaryOperators<TMat22, T>,
public TVecComparisonOperators<TMat22, T>,
public TVecAddOperators<TMat22, T>,
public TMatProductOperators<TMat22, T>,
public TMatSquareFunctions<TMat22, T>,
public TMatHelpers<TMat22, T>,
public TMatDebug<TMat22, T> {
public:
enum no_init { NO_INIT };
typedef T value_type;
typedef T& reference;
typedef T const& const_reference;
typedef size_t size_type;
typedef TVec2<T> col_type;
typedef TVec2<T> row_type;
static constexpr size_t COL_SIZE = col_type::SIZE; // size of a column (i.e.: number of rows)
static constexpr size_t ROW_SIZE = row_type::SIZE; // size of a row (i.e.: number of columns)
static constexpr size_t NUM_ROWS = COL_SIZE;
static constexpr size_t NUM_COLS = ROW_SIZE;
private:
/*
* <-- N columns -->
*
* a[0][0] a[1][0] a[2][0] ... a[N][0] ^
* a[0][1] a[1][1] a[2][1] ... a[N][1] |
* a[0][2] a[1][2] a[2][2] ... a[N][2] M rows
* ... |
* a[0][M] a[1][M] a[2][M] ... a[N][M] v
*
* COL_SIZE = M
* ROW_SIZE = N
* m[0] = [ a[0][0] a[0][1] a[0][2] ... a[0][M] ]
*/
col_type m_value[NUM_COLS];
public:
// array access
inline constexpr col_type const& operator[](size_t column) const {
#if __cplusplus >= 201402L
// only possible in C++0x14 with constexpr
assert(column < NUM_COLS);
#endif
return m_value[column];
}
inline col_type& operator[](size_t column) {
assert(column < NUM_COLS);
return m_value[column];
}
/**
* constructors
*/
/**
* leaves object uninitialized. use with caution.
*/
constexpr explicit TMat22(no_init) {}
/**
* initialize to identity.
*
* \f$
* \left(
* \begin{array}{cc}
* 1 & 0 \\
* 0 & 1 \\
* \end{array}
* \right)
* \f$
*/
constexpr TMat22();
/**
* initialize to Identity*scalar.
*
* \f$
* \left(
* \begin{array}{cc}
* v & 0 \\
* 0 & v \\
* \end{array}
* \right)
* \f$
*/
template<typename U>
constexpr explicit TMat22(U v);
/**
* sets the diagonal to a vector.
*
* \f$
* \left(
* \begin{array}{cc}
* v[0] & 0 \\
* 0 & v[1] \\
* \end{array}
* \right)
* \f$
*/
template <typename U>
constexpr explicit TMat22(const TVec2<U>& v);
/**
* construct from another matrix of the same size
*/
template <typename U>
constexpr explicit TMat22(const TMat22<U>& rhs);
/**
* construct from 2 column vectors.
*
* \f$
* \left(
* \begin{array}{cc}
* v0 & v1 \\
* \end{array}
* \right)
* \f$
*/
template <typename A, typename B>
constexpr TMat22(const TVec2<A>& v0, const TVec2<B>& v1);
/** construct from 4 elements in column-major form.
*
* \f$
* \left(
* \begin{array}{cc}
* m[0][0] & m[1][0] \\
* m[0][1] & m[1][1] \\
* \end{array}
* \right)
* \f$
*/
template <
typename A, typename B,
typename C, typename D>
constexpr explicit TMat22(A m00, B m01,
C m10, D m11);
struct row_major_init {
template<
typename A, typename B,
typename C, typename D>
constexpr explicit row_major_init(A m00, B m01,
C m10, D m11) noexcept
: m(m00, m10,
m01, m11) {}
private:
friend TMat22;
TMat22 m;
};
constexpr explicit TMat22(row_major_init c) : TMat22(std::move(c.m)) { }
/**
* Rotate by radians in the 2D plane
*/
static TMat22<T> rotate(T radian) {
TMat22<T> r(TMat22<T>::NO_INIT);
T c = std::cos(radian);
T s = std::sin(radian);
r[0][0] = c; r[1][1] = c;
r[0][1] = s; r[1][0] = -s;
return r;
}
// returns false if the two matrices are different. May return false if they're the
// same, with some elements only differing by +0 or -0. Behaviour is undefined with NaNs.
static constexpr bool fuzzyEqual(TMat22 l, TMat22 r) noexcept {
uint64_t const* const li = reinterpret_cast<uint64_t const*>(&l);
uint64_t const* const ri = reinterpret_cast<uint64_t const*>(&r);
uint64_t result = 0;
// For some reason clang is not able to vectoize this loop when the number of iteration
// is known and constant (!?!?!). Still this is better than operator==.
#pragma clang loop vectorize_width(2)
for (size_t i = 0; i < sizeof(TMat22) / sizeof(uint64_t); i++) {
result |= li[i] ^ ri[i];
}
return result != 0;
}
template <typename A>
static constexpr TMat22 translate(const TVec2<A>& t) {
TMat22 r;
r[2] = t;
return r;
}
template <typename A>
static constexpr TMat22 translate(A t) {
TMat22 r;
r[1] = TVec2<T>{ t };
return r;
}
template <typename A>
static constexpr TMat22 scale(const TVec2<A>& s) {
return TMat22{ s };
}
template <typename A>
static constexpr TMat22 scale(A s) {
return TMat22{ TVec2<T>{ s, s } };
}
};
// ----------------------------------------------------------------------------------------
// Constructors
// ----------------------------------------------------------------------------------------
// Since the matrix code could become pretty big quickly, we don't inline most
// operations.
template <typename T>
constexpr TMat22<T>::TMat22() {
m_value[0] = col_type(1, 0);
m_value[1] = col_type(0, 1);
}
template <typename T>
template <typename U>
constexpr TMat22<T>::TMat22(U v) {
m_value[0] = col_type(v, 0);
m_value[1] = col_type(0, v);
}
template<typename T>
template<typename U>
constexpr TMat22<T>::TMat22(const TVec2<U>& v) {
m_value[0] = col_type(v.x, 0);
m_value[1] = col_type(0, v.y);
}
// construct from 4 scalars. Note that the arrangement
// of values in the constructor is the transpose of the matrix
// notation.
template<typename T>
template <
typename A, typename B,
typename C, typename D>
constexpr TMat22<T>::TMat22(A m00, B m01,
C m10, D m11) {
m_value[0] = col_type(m00, m01);
m_value[1] = col_type(m10, m11);
}
template <typename T>
template <typename U>
constexpr TMat22<T>::TMat22(const TMat22<U>& rhs) {
for (size_t col = 0; col < NUM_COLS; ++col) {
m_value[col] = col_type(rhs[col]);
}
}
// Construct from 2 column vectors.
template <typename T>
template <typename A, typename B>
constexpr TMat22<T>::TMat22(const TVec2<A>& v0, const TVec2<B>& v1) {
m_value[0] = v0;
m_value[1] = v1;
}
// ----------------------------------------------------------------------------------------
// Arithmetic operators outside of class
// ----------------------------------------------------------------------------------------
/* We use non-friend functions here to prevent the compiler from using
* implicit conversions, for instance of a scalar to a vector. The result would
* not be what the caller expects.
*
* Also note that the order of the arguments in the inner loop is important since
* it determines the output type (only relevant when T != U).
*/
// matrix * column-vector, result is a vector of the same type than the input vector
template <typename T, typename U>
constexpr typename TMat22<U>::col_type PURE operator *(const TMat22<T>& lhs, const TVec2<U>& rhs) {
// Result is initialized to zero.
typename TMat22<U>::col_type result = {};
for (size_t col = 0; col < TMat22<T>::NUM_COLS; ++col) {
result += lhs[col] * rhs[col];
}
return result;
}
// row-vector * matrix, result is a vector of the same type than the input vector
template <typename T, typename U>
constexpr typename TMat22<U>::row_type PURE operator *(const TVec2<U>& lhs, const TMat22<T>& rhs) {
typename TMat22<U>::row_type result;
for (size_t col = 0; col < TMat22<T>::NUM_COLS; ++col) {
result[col] = dot(lhs, rhs[col]);
}
return result;
}
// matrix * scalar, result is a matrix of the same type than the input matrix
template<typename T, typename U>
constexpr typename std::enable_if<std::is_arithmetic<U>::value, TMat22<T>>::type PURE
operator*(TMat22<T> lhs, U rhs) {
return lhs *= rhs;
}
// scalar * matrix, result is a matrix of the same type than the input matrix
template<typename T, typename U>
constexpr typename std::enable_if<std::is_arithmetic<U>::value, TMat22<T>>::type PURE
operator*(U lhs, const TMat22<T>& rhs) {
return rhs * lhs;
}
// ----------------------------------------------------------------------------------------
/* FIXME: this should go into TMatSquareFunctions<> but for some reason
* BASE<T>::col_type is not accessible from there (???)
*/
template<typename T>
constexpr typename TMat22<T>::col_type PURE diag(const TMat22<T>& m) {
return matrix::diag(m);
}
} // namespace details
// ----------------------------------------------------------------------------------------
typedef details::TMat22<double> mat2;
typedef details::TMat22<float> mat2f;
// ----------------------------------------------------------------------------------------
} // namespace math
#undef PURE
namespace std {
template <typename T>
constexpr void swap(math::details::TMat22<T>& lhs, math::details::TMat22<T>& rhs) noexcept {
// This generates much better code than the default implementation
// It's unclear why, I believe this is due to an optimization bug in the clang.
//
// math::details::TMat22<T> t(lhs);
// lhs = rhs;
// rhs = t;
//
// clang always copy lhs on the stack, even if it's never using it (it's using the
// copy it has in registers).
const T t00 = lhs[0][0];
const T t01 = lhs[0][1];
const T t10 = lhs[1][0];
const T t11 = lhs[1][1];
lhs[0][0] = rhs[0][0];
lhs[0][1] = rhs[0][1];
lhs[1][0] = rhs[1][0];
lhs[1][1] = rhs[1][1];
rhs[0][0] = t00;
rhs[0][1] = t01;
rhs[1][0] = t10;
rhs[1][1] = t11;
}
}
#endif // MATH_MAT2_H_