magnum/doc/getting-started.dox

/*
    This file is part of Magnum.

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

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*/

namespace Magnum {
/** @page getting-started Getting started
@brief Get started with Magnum in matter of minutes.

@tableofcontents

Setting up a new project can be pretty gruesome and nobody likes repeating the
same process every time. Magnum provides "bootstrap" project structures for
many use cases, helping you get up and running in no time.

@section getting-started-bootstrap Download bootstrap project

The [bootstrap repository](https://github.com/mosra/magnum-bootstrap) is
located on GitHub. The `master` branch contains just an README file and the
actual bootstrap projects are in various other branches, each covering some
particular use case. For the first project you need the `base` branch, which
contains only the essential files. Download the branch [as an archive](https://github.com/mosra/magnum-bootstrap/archive/base.zip)
and extract it somewhere. Do it rather than cloning the full repository, as
it's better to init your own repository from scratch with clean history.

If you want to (or have to) use GLUT instead of SDL2, download the `base-glut`
branch [archive](https://github.com/mosra/magnum-bootstrap/archive/base-glut.zip)
instead of `base` branch. The code will be slightly different from what is
presented below, but the changes are only minor (two modified lines) and the
main principles are the same.

@section getting-started-download Download, build and install Corrade and Magnum

Magnum libraries support both separate compilation/installation and CMake
subprojects. We'll use the subproject approach now, because adding the
dependencies means just cloning them into your project tree:

    cd /path/to/the/extracted/bootstrap/project
    git clone git://github.com/mosra/corrade.git
    git clone git://github.com/mosra/magnum.git

Then open the `CMakeLists.txt` file in the root of bootstrap project and add
these two new subdirectories using `add_subdirectory()` so the file looks like
this:

@code
cmake_minimum_required(VERSION 2.8.12)
project(MyApplication)

set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/modules/")

add_subdirectory(corrade)
add_subdirectory(magnum)
add_subdirectory(src)
@endcode

If you want to install Corrade and Magnum separately instead of cloning them
into your project tree, just follow @ref building "the full installation guide".
Don't forget to enable `WITH_SDL2APPLICATION` (or `WITH_GLUTAPPLICATION`, if
you are using GLUT) when building Magnum so the bootstrap project can use it
later.

@section getting-started-review Review project structure

The base project consists of just six files in two subfolders. Magnum uses
CMake build system, see @ref cmake for more information.

    modules/FindCorrade.cmake
    modules/FindMagnum.cmake
    modules/FindSDL2.cmake
    src/MyApplication.cpp
    src/CMakeLists.txt
    CMakeLists.txt

In root there is project-wide `CMakeLists.txt`, which you have seen above. It
just sets up project name, specifies module directory and delegates everything
important to `CMakeLists.txt` in `src/` subdirectory.

Directory `modules/` contains CMake modules for finding the needed
dependencies. Unlike modules for finding e.g. OpenGL, which are part of
standard CMake installation, these aren't part of it and thus must be
distributed with the project. These files are just verbatim copied from Magnum
repository.

@note These modules are just the bare minimum you need for starting. If you
    plan to use additional functionality not part of the core library or target
    specific platforms, you may need to copy additional modules. See @ref cmake,
    @ref cmake-plugins, @ref cmake-integration and @ref cmake-extras for more
    information.

Directory `src/` contains the actual project. To keep things simple, the
project consists of just one source file with the most minimal code possible:
@code
#include <Magnum/DefaultFramebuffer.h>
#include <Magnum/Platform/Sdl2Application.h>

using namespace Magnum;

class MyApplication: public Platform::Application {
    public:
        explicit MyApplication(const Arguments& arguments);

    private:
        void drawEvent() override;
};

MyApplication::MyApplication(const Arguments& arguments): Platform::Application{arguments} {
    // TODO: Add your initialization code here
}

void MyApplication::drawEvent() {
    defaultFramebuffer.clear(FramebufferClear::Color);

    // TODO: Add your drawing code here

    swapBuffers();
}

MAGNUM_APPLICATION_MAIN(MyApplication)
@endcode

The application essentially does nothing, just clears screen framebuffer to
default (dark gray) color and then does buffer swap to actually display it on
the screen. The `src/CMakeLists.txt` file finds Magnum, creates the executable
and links it to all needed libraries:
@code
find_package(Magnum REQUIRED Sdl2Application)

set_directory_properties(PROPERTIES CORRADE_USE_PEDANTIC_FLAGS ON)

add_executable(MyApplication MyApplication.cpp)
target_link_libraries(MyApplication
    Magnum::Magnum
    Magnum::Application)
@endcode

In the following tutorials the code will be explained more thoroughly.

@section getting-started-build Build it and run

In Linux (and other Unix-based OSs) you can build the application along with
the subprojects using the following three commands: create out-of-source build
directory, run cmake, enable SDL2 application in the Magnum subproject and then
build everything. The compiled application binary will then appear in `src/`
subdirectory of the build dir:

    mkdir -p build && cd build
    cmake .. -DWITH_SDL2APPLICATION=ON
    cmake --build .
    ./src/MyApplication

On Windows you can use either MSVC or MinGW-w64 compiler and prebuilt SDL2
binaries can be downloaded at https://libsdl.org/download-2.0.php. It's then up
to you whether you will use command-line, QtCreator or Visual Studio. With
Visual Studio the most straightforward way to create the project file is via
the command-line:

    mkdir build && cd build
    cmake .. -DWITH_SDL2APPLICATION=ON

You can also use CMake GUI. Then open the `MyApplication.sln` project file
generated by CMake in the build directory.

With QtCreator just open project's root `CMakeLists.txt` file. It then asks you
where to create build directory, allows you to specify initial CMake parameters
(e.g. the `-DWITH_SDL2APPLICATION=ON` parameter) and then you can just press *Configure*
and everything is ready to be built.

If you have SDL2 in a non-standard location and CMake can't find it, you need
to specify where SDL `include/` and `lib/` directories are through
`CMAKE_PREFIX_PATH`. So, for example, on Windows, the full CMake invocation
might look like this:

    cmake .. -DCMAKE_PREFIX_PATH="C:/Users/you/Downloads/SDL2-2.0.4" -DWITH_SDL2APPLICATION=ON

On Windows you may get errors about missing DLLs when running the application.
The solution is either compiling everything as static (enable `BUILD_STATIC`
CMake option) or installing the dependencies somewhere. To install them, change
`CMAKE_INSTALL_PREFIX` to your liking and run the `install` target. Then run
the application with `bin/` subdirectory of installation prefix as working dir
or add the `bin/` subdirectory to `PATH`.

@image html getting-started.png
@image latex getting-started.png

Now you can try to change something in the code. Without going too deep into
the concepts of graphics programming, we can change clear color to something
else and also print basic information about the GPU the engine is running on.
First include the needed headers:
@code
#include <Magnum/Context.h>
#include <Magnum/Renderer.h>
#include <Magnum/Version.h>
#include <Magnum/Math/Color.h>
@endcode

And in the constructor (which is currently empty) change the clear color and
print something to debug output:
@code
using namespace Magnum::Math::Literals;

Renderer::setClearColor(Color3::fromHSV(216.0_degf, 0.85f, 1.0f));

Debug() << "Hello! This application is running on" << Context::current().version()
        << "using" << Context::current().rendererString();
@endcode

After rebuilding and starting the application, the clear color changes to
blueish one and something like this would be printed to the console:

> Hello! This application is running on OpenGL 4.5 using GeForce GT 740M

@image html getting-started-blue.png
@image latex getting-started-blue.png

@section getting-started-tutorials Follow tutorials and learn the principles

Now that you have your first application up and running, the best way to
continue is to render your first triangle in @ref example-index "step-by-step tutorial".
Then you can dig deeper and try other examples, read about
@ref features "fundamental principles" in the documentation and start
experimenting on your own!

@section getting-started-more Additional information

-   @subpage building
-   @subpage building-plugins
-   @subpage building-integration
-   @subpage building-examples
-   @subpage building-extras
-   @subpage cmake
-   @subpage cmake-plugins
-   @subpage cmake-integration
-   @subpage cmake-extras

*/
}