Vec4#
#include <Imath/ImathVec.h>
The Vec4 class template represents a 4D vector, with predefined
typedefs for vectors of type short, int, int64_t,
float, and double.
Note that the integer specializations of Vec4 lack the
length() and normalize() methods that are present in the
float and double versions, because the results don’t fit into
integer quantities.
There are also various utility functions that operate on vectors
defined in ImathVecAlgo.h and described in Vector Functions.
Individual components of a vector V may be referenced as either V[i]
or V.x, V.y, V.z, V.w. Obviously, the [] notation is more
suited to looping over components, or in cases where a variable determines
which coordinate is needed. However, when the coordinate is known, it can be
more efficient to directly address the components, such as V.y rather than
V[1]. While both appear to do the same thing (and indeed do generate the
same machine operations for ordinary scalar code), when used inside loops that
you hope to parallelize (either through compiler auto-vectorization or
explicit hints such as #pragma omp simd), the function call and
pointer casting of operator[] can confuse the compiler just enough to
prevent vectorization of the loop.
Example:
#include <Imath/ImathVec.h>
#include <cassert>
void
vec4_example ()
{
Imath::V4f a (1.0f, 2.0f, 3.0f, 4.0f);
Imath::V4f b; // b is uninitialized
b.x = a[0];
b.y = a[1];
b.z = a[2];
b.w = a[3];
assert (a == b);
assert (a.length () == sqrt (a ^ a));
a.normalize ();
assert (Imath::equalWithAbsError (a.length (), 1.0f, 1e-6f));
}
-
template<class T>
class Vec4# 4-element vector
Constructors and Assignment
-
inline Vec4() noexcept#
Uninitialized by default.
-
template<class S>
inline constexpr Vec4(const Vec4<S> &v) noexcept# Construct from Vec4 of another base type.
-
~Vec4() noexcept = default#
Destructor.
Compatibility with Sb
Arithmetic and Comparison
-
inline constexpr bool equalWithAbsError(const Vec4<T> &v, T e) const noexcept#
Compare two vectors and test if they are “approximately equal”:
- Returns:
True if the components of this and
vare the same with an absolute error of no more than e, i.e., for all i:abs (this[i] - v[i]) <= e
-
inline constexpr bool equalWithRelError(const Vec4<T> &v, T e) const noexcept#
Compare two vectors and test if they are “approximately equal”:
- Returns:
True if the components of this and
vare the same with a relative error of no more than e, i.e., for all i:abs (this[i] - v[i]) <= e * abs (this[i])
Query and Manipulation
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
inline T length() const noexcept# Return the Euclidean norm.
-
inline constexpr T length2() const noexcept#
Return the square of the Euclidean norm, i.e.
the dot product with itself.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
const Vec4 &normalize() noexcept# Normalize in place. If length()==0, return a null vector.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
const Vec4 &normalizeExc()# Normalize in place. If length()==0, throw an exception.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
const Vec4 &normalizeNonNull() noexcept# Normalize without any checks for length()==0.
Slightly faster than the other normalization routines, but if v.length() is 0.0, the result is undefined.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
inline Vec4<T> normalized() const noexcept# Return a normalized vector. Does not modify *this.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
inline Vec4<T> normalizedExc() const# Return a normalized vector.
Does not modify *this. Throw an exception if length()==0.
-
template<typename S = T, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int> = 0>
inline Vec4<T> normalizedNonNull() const noexcept# Return a normalized vector.
Does not modify *this, and does not check for length()==0. Slightly faster than the other normalization routines, but if v.length() is 0.0, the result is undefined.
Numeric Limits
Public Types
Public Functions
-
inline constexpr T &operator[](int i) noexcept#
Element access by index.
NB: This method of access uses dynamic array accesses which can prevent compiler optimizations and force temporaries to be stored to the stack and other missed vectorization opportunities. Use of direct access to x, y, z, w when possible should be preferred.
-
inline constexpr const T &operator[](int i) const noexcept#
Element access by index.
NB: This method of access uses dynamic array accesses which can prevent compiler optimizations and force temporaries to be stored to the stack and other missed vectorization opportunities. Use of direct access to x, y, z, w when possible should be preferred.
-
template<typename S, IMATH_NAMESPACE::enable_if_t<(is_float_like<S>::value), int>>
inline const Vec4<T> &normalize() noexcept#
Public Static Functions
-
static inline constexpr unsigned int dimensions() noexcept#
Return the number of dimensions, i.e. 4.
-
inline Vec4() noexcept#
