/*
    This file is part of Magnum.

    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019,
                2020, 2021, 2022 Vladimír Vondruš <mosra@centrum.cz>

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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    DEALINGS IN THE SOFTWARE.
*/

namespace Magnum {

/** @page features Feature guide
@brief High-level introduction to design of the Magnum library and basic building blocks.

@m_keywords{Features}

@tableofcontents

@todoc FUCK OFF doxygen, why are you not able to link to Corrade, Corrade::Utility and Magnum/Math/ you dumb shit?!

Before you continue further, here are the essential bits of knowledge to help
you around.

@section features-naming Library organization and naming scheme

The @ref Magnum project consists of a library with core functionality and
optional sub-libraries. Each library is in its own namespace, which corresponds
to a sub-folder on the include path -- so e.g. things from @ref Magnum::Math
are included from @m_class{m-doc} [Magnum/Math/](dir_d816e7cf853e6723911731706bcab386.html).
@ref Magnum builds upon
@m_class{m-doc-external} [Corrade](https://doc.magnum.graphics/corrade/), which
provides platform abstraction, basic utilities and containers.

To reduce redundant verbosity, references throughout the documentation and
code in example snippets have the root @ref Magnum and
@m_class{m-doc-external} [Corrade](https://doc.magnum.graphics/corrade/namespaceCorrade.html)
namespaces omitted. In other words, as if the following was done:

@snippet Magnum.cpp features-using-namespace

If Magnum is the primary library you're building your project on, it's
recommended that you do the same --- we're careful to not pollute the root
namespace with overly generic names. However, except for `Literals` namespaces,
@cpp using @ce the subnamespaces is *not recommended*, as naming in those is
deliberately picked short and may introduce conflicts (such as
@relativeref{Corrade,Containers::String} vs
@relativeref{Corrade,Utility::String} or @ref GL::PixelFormat vs
@ref Vk::PixelFormat).

If you frown upon the thought of @cpp using namespace Magnum @ce yet don't want
to wear your fingers off by repeatedly writing @cpp Magnum:: @ce everywhere, a
common shorthand that projects go with is the following --- similarly in spirit
to @cb{.py} import numpy as np @ce:

@snippet Magnum.cpp features-using-namespace-alias

@section features-includes Include files and forward declarations

Depending on where you come from, the @cpp #include @ce policy used by Magnum
might either make you happy or freak you out. In short, there's no "include the
world" file, and instead you're supposed to include dedicated headers for APIs
you want to use. The main reason is compile times, and the speed gain from
doing it this way is too great to be ignored.

The general rule is that each top-level class has a corresponding include, so
for example @ref Math::Matrix4 is included as @ref Magnum/Math/Matrix4.h. It's
not always like that though, and to help you out, documentation of each
namespace and class tells you what to include, and if particular namespace
members are defined in different headers, then detailed docs of each has a
corresponding @cpp #include @ce directive listed as well, ready to be copied.

In order to have the includes actually independent of each other, most Magnum
types are forward-declared, and where possible, the header only relies on
forward declarations. Which means that often the type already exists as a
declaration, and in order to actually use it, you have to include the concrete
definition of it. If you don't, the compiler will complain about use of an
incomplete type. For example:

@snippet Magnum.cpp features-forward-declaration-use

Of course not all headers can be written with just forward declarations, so
there still are some transitive dependencies between headers (for example, the
@ref Magnum/Math/Matrix4.h header pulls in @ref Magnum/Math/Vector4.h as well).
But from most part this is an implementation detail and as such shouldn't be
relied on.

For happy compile times you're encouraged to rely on forward declarations in
your code as well. See @ref compilation-forward-declarations for more
information.

@section features-debug-output Debug output

One of the essential debugging workflows is inspection of variable contents by
printing them out. Magnum defines a lot of new math types, enums and
containers and it would be very painful if you had to loop over their contents
or perform manual enum-to-string conversion every time you want to see what's
inside.

Because writing to standard output and printing values for debugging purposes
are *distinct* use cases with potentially conflicting requirements (should an
enum value get written as a number? or as a name? a fully qualified name?),
Magnum *doesn't* provide @cpp operator<< @ce overloads for @ref std::ostream.

Instead, there's @relativeref{Corrade,Utility::Debug} (and its variants,
@relativeref{Corrade,Utility::Warning}, @relativeref{Corrade,Utility::Error}
and @relativeref{Corrade,Utility::Fatal}), for your typing convenience also
aliased to just @ref Debug / @ref Warning / @ref Error directly in the
@ref Magnum namespace. On its own it's able to print builtin types, all usual
C++ containers as well as their Corrade equivalents. Magnum then implements
debug printers for its own math types, basic structures and most enums, which
get printed as fully-qualified names. For example:

@m_class{m-code-figure}

@parblock

@snippet Magnum.cpp features-debug-output

<b></b>

@m_class{m-nopad}

@code{.shell-session}
Image format is PixelFormat::RGBA8Srgb and size Vector(256, 192)
Color of the bottom-left pixel is #33b27f
@endcode

@endparblock

The main goal of this utility is convenience and readability ---  values are
implicitly delimited by spaces and ended with a newline, container contents
written with commas etc. Check out the class documentation for advanced
features like colors, output redirection or printing file/line info.

@section features-error-handling Error handling in Magnum

Magnum differentiates between two kinds of errors --- a programmer error (for
example an out-of-bounds access) and a runtime error (for example when a file
can't be opened). Programmer errors are assertions, directly leading to a
program abort. Runtime errors expect *you* to do the error handling, and if you
don't do that, then you're likely to hit an assertion --- a programmer error
--- shortly after.

The assertions are deliberately not recoverable and are by default
@ref CORRADE_NO_ASSERT "kept in release builds as well". A lot of effort is put
into assertion messages, which clearly show you what went wrong. They get
always printed to the standard output or its equivalent, see
the @ref troubleshooting-runtime "troubleshooting guide" for ways how to
retrieve it on various platforms.

To avoid polluting user code with excessive error handling, runtime errors are
restricted only where strictly necessary, and always documented as such. For
performance and portability reasons, exceptions aren't used, Instead, the
errors usually manifest as an invalid return value (for example an empty
@relativeref{Corrade,Containers::Optional}) and a diagnostic message
accompanying the error is printed via @relativeref{Corrade,Utility::Error}.
If needed, you can optionally
@ref Utility-Debug-scoped-output "redirect the message to a string or a log file".

@section features-examples Learn by example

Before you do a deep dive into the documentation, and if you haven't done
already, it's recommended to go through the Getting Started Guide and check out
at least the first example:

@m_class{m-row}

@parblock

@m_div{m-col-t-8 m-push-t-2 m-col-s-6 m-push-s-0 m-col-m-4 m-push-m-1} @m_div{m-button m-primary m-fullwidth} <a href="getting-started.html">@m_div{m-big}Getting Started@m_enddiv @m_div{m-small} bootstrap a basic project structure @m_enddiv </a> @m_enddiv @m_enddiv

@m_div{m-col-t-8 m-push-t-2 m-col-s-6 m-push-s-0 m-col-m-4 m-push-m-3} @m_div{m-button m-success m-fullwidth} <a href="examples-triangle.html">@m_div{m-big}Your First Triangle@m_enddiv @m_div{m-small} a step-by-step tutorial @m_enddiv </a> @m_enddiv @m_enddiv

@endparblock

@section features-building-blocks Learn through documentation

Each of the following pages provides a high-level description of a certain area
of the library. It's recommended to read through these first to understand the
overall principles and only then go to documentation of each concrete class and
function.

-   @subpage platform --- @copybrief platform
-   @subpage types --- @copybrief types
-   @subpage matrix-vector --- @copybrief matrix-vector
-   @subpage transformations --- @copybrief transformations
-   @subpage animation --- @copybrief animation
-   @subpage plugins --- @copybrief plugins
-   @subpage file-formats --- @copybrief file-formats
-   @subpage opengl-wrapping --- @copybrief opengl-wrapping
-   @subpage vulkan-wrapping --- @copybrief vulkan-wrapping
-   @subpage shaders --- @copybrief shaders
-   @subpage scenegraph --- @copybrief scenegraph
-   @subpage debug-tools --- @copybrief debug-tools
-   @subpage ui --- @copybrief ui
*/

}