I don't know why, but marking the output of copy constructor of any
subclass or output of conversion operator of any class as constexpr
causes MSVC to complain about non-constant expression.
Probably just another bug.
Apart from different include (<Magnum/Math/Color.h> instead of
<Magnum/Color.h>) there shouldn't be any visible change to the user. The
BasicColor3 and BasicColor4 classes are now Math::Color3 and
Math::Color4. The Color3, Color4, Color3ub and Color4ub typedefs in
Magnum namespace stayed the same.
BasicColor3 and BasicColor4 is now an alias to Math::Color3 and
Math::Color4, is marked as deprecated and will be removed in future
release. The same goes for the <Magnum/Color.h> include, which now just
includes the <Magnum/Math/Color.h> header.
Useful for squeezing out last bits of performance, e.g. in this case:
Vector3 a;
a[0] = something++;
a[1] = something++;
a[2] = something++;
In the code all elements are first zeroed out and then overwritten
later, thus it might be good to avoid the zero-initialization:
Vector3 a{Math::NoInit};
a[0] = something++;
a[1] = something++;
a[2] = something++;
This will of course be more useful in far larger data types and arrays
of these.
Previously only matrices allowed to be created either as an identity or
zero-initialized. Now all Math classes support that, including (dual)
complex numbers and quaternions.
Some classes are by default constructed zero-filled while other are set
to identity and the only way to to check this is to look into the
documentation. This changes the default constructor of all classes to
take an optional "tag" which acts as documentation about how the type is
constructed. Note that this result in no behavioral changes, just
ability to be more explicit when writing the code. Example:
// These two are equivalent
Quaternion q1;
Quaternion q2{Math::IdentityInit};
// These two are equivalent
Vector4 vec1;
Vector4 vec2{Math::ZeroInit};
Matrix4 a{Math::IdentityInit, 2}; // 2 on diagonal
Matrix4 b{Math::ZeroInit}; // all zero
This functionality was already present in some ugly form in Matrix,
Matrix3 and Matrix4 classes. It was long and ugly to write, so it is
now generalized into the new Math::IdentityInit and Math::ZeroInit tags,
the original Matrix::IdentityType, Matrix::Identity, Matrix::ZeroType
and Matrix::Zero are deprecated and will be removed in the future
release.
Math::Matrix<7, Int> m{Math::Matrix<7, Int>::Identity}; // before
Math::Matrix<7, Int> m{Math::IdentityInit}; // now
It is often annoying to write e.g. this, especially in generic code:
T dot = Math::Vector<size, T>::dot(a, b);
When this is more than enough and the compiler can infer the rest from
the context:
T dot = Math::dot(a, b);
There are more downsides and confusing cases (you can call
Math::Vector<3, T>::dot(), Math::Vector3<T>::dot() and Color3::dot() and
it is still the same function), so I made these as free functions in
Math namespace. You can now also abuse ADL for the calls, but I would
advise against that for better readability:
T d = dot(a, b); // dot?! what on earth is dot? and what is a?
The only downside found when porting is that you need to specify the
type somehow when having both parameters as initializer lists:
T d = dot({2.0f, -1.5f}, {1.0f, 2.5f}); // error
T d = dot(Complex{2.0f, -1.5f}, {1.0f, 2.5f}); // okay
But that's probably reasonable (and it's also highly corner case,
the functions were used this way only in tests).
The original static member functions are of course still present, but
marked as deprecated and will be removed at some point in future.
Using std::numeric_limits for the Double variants looks like an overkill
to me, but there apparently isn't any other way, except for crafting the
value manually using the exact binary representation (and hoping it will
be portable) or producing the value as result of division by zero or
something like that (and then working around the warnings and also
hoping it will be portable).
Constants::piHalf() is not longer to write than doing the division
manually and it has significantly smaller mental overhead. Also I chose
piHalf() instead of halfPi() to make it more discoverable through
autocompletion.
Float a = Constants::pi()*0.5f;
Float a = Constants::piHalf();
Float b = Constants::pi()/(2*countOfSomething);
Float b = Constants::piHalf()/countOfSomething;
Vladimír Vondruš