glfw/docs/moving.dox

/*!

@page moving Moving from GLFW 2 to 3

@tableofcontents

This is a transition guide for moving from GLFW 2 to 3.  It describes what has
changed or been removed, but does *not* include entirely new features unless
they are required when moving an existing code base onto the new API.  For example,
use of the new multi-monitor support is required to create fullscreen windows.


@section moving_removed Removed features

@subsection moving_threads Threading functions

The threading functions have been removed, including the sleep function.  They
were fairly primitive, under-used, poorly integrated and took time away from the
focus of GLFW (i.e.  context, input and window).  There are better threading
libraries available and native threading support is available in both C++11 and
C11, both of which are gaining traction. 

If you wish to use the C++11 or C11 facilities but your compiler doesn't yet
support them, see the
[TinyThread++](https://gitorious.org/tinythread/tinythreadpp) and
[TinyCThread](https://gitorious.org/tinythread/tinycthread) projects created by
the original author of GLFW.  These libraries implement a usable subset of the
threading APIs in C++11 and C11, and in fact some GLFW 3 test programs use
TinyCThread.

However, GLFW 3 has better support for *use from multiple threads* than GLFW
2 had.  Contexts can be made current on and rendered with from secondary
threads, and the documentation explicitly states which functions may or may not
be used from secondary threads.


@subsection moving_image Image and texture loading

The image and texture loading functions have been removed.  They only supported
the Targa image format, making them mostly useful for beginner level examples.
To become of sufficiently high quality to warrant keeping them in GLFW 3, they
would need not only to support other formats, but also modern extensions to the
OpenGL texturing facilities.  This would either add a number of external
dependencies (libjpeg, libpng, etc.), or force GLFW to ship with inline versions
of these libraries. 

As there already are libraries doing this, it seems unnecessary both to
duplicate this work and to tie this duplicate to GLFW.  Projects similar to
GLFW, such as freeglut, could also gain from such a library.  Also, would be no
platform-specific part of such a library, as both OpenGL and stdio are available
wherever GLFW is.


@subsection moving_char_up Character actions

The action parameter of the [character callback](@ref GLFWcharfun) has been
removed.  This was an artefact of the origin of GLFW, i.e. being developed in
English by a Swede.  However, many keyboard layouts require more than one key to
produce characters with diacritical marks. Even the Swedish keyboard layout
requires this for uncommon cases like ü.

Note that this is only the removal of the *action parameter* of the character
callback, *not* the removal of the character callback itself. 


@subsection moving_wheel Mouse wheel position

Scroll events do not represent an absolute state.  Instead, it's an
interpretation of a relative change in state, like character input.  So, like
character input, there is no sane 'current state' to return.  The mouse wheel
callback has been replaced by a [scroll callback](@ref GLFWscrollfun) that
receives two-dimensional scroll offsets.


@subsection moving_stdcall GLFWCALL macro

The `GLFWCALL` macro, which made callback functions use
[__stdcall](http://msdn.microsoft.com/en-us/library/zxk0tw93.aspx) on Windows,
has been removed.  GLFW is written in C, not Pascal.  Removing this macro means
there's one less thing for users of GLFW to remember, i.e. the requirement to
mark all callback functions with `GLFWCALL`.  It also simplifies the creation of
DLLs and DLL link libraries, as there's no need to explicitly disable `@n` entry
point suffixes. 


@subsection moving_mbcs Win32 MBCS support

The Win32 port of GLFW 3 will not compile in
[MBCS mode](http://msdn.microsoft.com/en-us/library/5z097dxa.aspx).
Hoever, because the use of the Unicode version of the Win32 API doesn't affect
the process as a whole, but only those windows created using it, it's perfectly
possible to call MBCS functions from other parts of the same application.
Therefore, even if an application using GLFW uses MBCS mode, there's no need for
GLFW itself to support it.


@subsection moving_windows Support for versions of Windows older than XP

All explicit support for version of Windows older than XP has been removed.
There is no code that actively prevents GLFW 3 from running on these earlier
versions, but it uses Win32 functions that those versions lack.

Windows XP was released in 2001, and by now (2013) it has not only
replaced almost all earlier versions of Windows, but is itself rapidly being
replaced by Windows 7 and 8.  The MSDN library doesn't even provide
documentation for version older than Windows 2000, making it difficult to
maintain compatibility with these versions even if it was deemed worth the
effort.

The Win32 API has also not stood still, and GLFW 3 uses many functions only
present on Windows XP or later.  Even supporting an OS as new as XP (new
from the perspective of GLFW 2, which still supports Windows 95) requires
runtime checking for a number of functions that are present only on modern
version of Windows.


@subsection moving_syskeys Capture of system-wide hotkeys

The ability to disable and capture system-wide hotkeys like Alt+Tab has been
removed.  Modern applications, whether they're games, scientific visualisations
or something else, are nowadays expected to be good desktop citizens and allow
these hotkeys to function even when running in fullscreen mode.


@subsection moving_terminate Automatic termination

@ref glfwTerminate is no longer registered with `atexit` at initialization.  To
properly release all resources allocated by GLFW, you should therefore call @ref
glfwTerminate yourself before exiting.


@section moving_changed Changes to existing features

@subsection moving_window_handles Window handles

Because GLFW 3 supports multiple windows, window handle parameters have been
added to all window-related GLFW functions and callbacks.  The handle of
a newly created window is returned by @ref glfwCreateWindow (formerly
`glfwOpenWindow`).  Window handles are of the `GLFWwindow*` type, i.e. a pointer
to an opaque struct.


@subsection moving_monitor Multi-monitor support

GLFW 3 provides support for multiple monitors, adding the `GLFWmonitor*` handle
type and a set of related functions.  To request a fullscreen mode window, you
need to specify which monitor you wish the window to use.  There is @ref
glfwGetPrimaryMonitor that provides behaviour similar to that of GLFW 2.


@subsection moving_window_close Window closing

Window closing is now just an event like any other.  GLFW 3 windows won't
disappear from underfoot even when no close callback is set; instead the
window's close flag is set.  You can query this flag using @ref
glfwWindowShouldClose, or capture close events by setting a close callback.  The
close flag can be modified from any point in your program using @ref
glfwSetWindowShouldClose.


@subsection moving_context Explicit context management

Each GLFW 3 window has its own OpenGL context and only you, the user, can know
which context should be current on which thread at any given time.  Therefore,
GLFW 3 makes no assumptions about when you want a certain context to be current,
leaving that decision to you.

This means, among other things, that you need to call @ref
glfwMakeContextCurrent after creating a window before you can call any OpenGL
functions.


@subsection moving_keys Physical key input

GLFW 3 uses the physical key locations named after the symbols they generate
using the US keyboard layout, instead of layout-dependent characters like in
GLFW 2.  This means that (for example) `GLFW_KEY_BACKSLASH` is always a single
key and is the same key in the same place regardless of what keyboard layouts
the users of your program has.

The key input facility was never meant for text input, although using it that
way worked slightly better in GLFW 2.  If you were using it to input text, you
should be using the character callback instead, on both GLFW 2 and 3.  This will
give you the characters being input, as opposed to the keys being pressed.

GLFW 3 has key tokens for all keys on a standard keyboard, so instead of having
to remember whether to check for `'a'` or `'A'`, you now check for `GLFW_KEY_A`.


@subsection moving_video_modes Video mode enumeration

Video mode enumeration is now per-monitor.  The `glfwGetDesktopMode` function
has been replaced by @ref glfwGetVideoMode, which returns the current mode of
a monitor.  The @ref glfwGetVideoModes function now returns all available modes
for a monitor instead of requiring you to guess how large an array you need.


@subsection moving_glu GLU header inclusion

Unlike GLFW 2, GLFW 3 doesn't include the GLU header by default, but you can
make it do so by defining `GLFW_INCLUDE_GLU` before the inclusion of the GLFW
3 header.


@subsection moving_cursor Cursor positioning

GLFW 3 only allows you to position the cursor within a window using @ref
glfwSetCursorPos (formerly `glfwSetMousePos`) when that window is active.
Unless the window is active, the function fails silently.


@subsection moving_hints Persistent window hints

Window hints are no longer reset to their default values on window creation, but
instead retain their values until modified by @ref glfwWindowHint (formerly
`glfwOpenWindowHint`) or @ref glfwDefaultWindowHints, or until the library is
terminated and re-initialized.


@section moving_renamed Name changes

@subsection moving_renamed_files Library and header file

The GLFW 3 header is named @ref glfw3.h, to avoid collisions with the GLFW 2
`glfw.h` header, in case they are both installed.  Similarly, the GLFW 3 library
is named `glfw3,` except when it's installed as a shared library on Unix-like
systems, where it uses the [soname](https://en.wikipedia.org/wiki/soname)
`libglfw.so.3`.


@subsection moving_renamed_functions Functions

| GLFW 2                      | GLFW 3                        | Notes |
| --------------------------- | ----------------------------- | ----- |
| `glfwOpenWindow`            | @ref glfwCreateWindow         | All channel bit depths are now hints
| `glfwCloseWindow`           | @ref glfwDestroyWindow        |       |
| `glfwOpenWindowHint`        | @ref glfwWindowHint           | Now accepts all `GLFW_*_BITS` tokens |
| `glfwEnable`                | @ref glfwSetInputMode         |       |
| `glfwDisable`               | @ref glfwSetInputMode         |       |
| `glfwGetMousePos`           | @ref glfwGetCursorPos         |       |
| `glfwSetMousePos`           | @ref glfwSetCursorPos         |       |
| `glfwSetMousePosCallback`   | @ref glfwSetCursorPosCallback |       |
| `glfwSetMouseWheelCallback` | @ref glfwSetScrollCallback    | Accepts two-dimensional scroll offsets as doubles |
| `glfwGetJoystickPos`        | @ref glfwGetJoystickAxes      |       |
| `glfwGetGLVersion`          | @ref glfwGetWindowParam       | Use `GLFW_OPENGL_VERSION_MAJOR`, `GLFW_OPENGL_VERSION_MINOR` and `GLFW_OPENGL_REVISION` |
| `glfwGetDesktopMode`        | @ref glfwGetVideoMode         | Returns the current mode of a monitor |

@subsection moving_renamed_tokens Tokens

| GLFW 2                      | GLFW 3                       | Notes |
| --------------------------- | ---------------------------- | ----- |
| `GLFW_OPENGL_VERSION_MAJOR` | `GLFW_CONTEXT_VERSION_MAJOR` | Renamed as it applies to OpenGL ES as well |
| `GLFW_OPENGL_VERSION_MINOR` | `GLFW_CONTEXT_VERSION_MINOR` | Renamed as it applies to OpenGL ES as well |
| `GLFW_FSAA_SAMPLES`         | `GLFW_SAMPLES`               | Renamed to match the OpenGL API |
| `GLFW_ACTIVE`               | `GLFW_FOCUSED`               | Renamed to match the window focus callback |
| `GLFW_WINDOW_NO_RESIZE`     | `GLFW_RESIZABLE`             | The default has been inverted |
| `GLFW_MOUSE_CURSOR`         | `GLFW_CURSOR_MODE`           | Used with @ref glfwSetInputMode |
| `GLFW_KEY_ESC`              | `GLFW_KEY_ESCAPE`            |       |
| `GLFW_KEY_DEL`              | `GLFW_KEY_DELETE`            |       |
| `GLFW_KEY_PAGEUP`           | `GLFW_KEY_PAGE_UP`           |       |
| `GLFW_KEY_PAGEDOWN`         | `GLFW_KEY_PAGE_DOWN`         |       |
| `GLFW_KEY_KP_NUM_LOCK`      | `GLFW_KEY_NUM_LOCK`          |       |
| `GLFW_KEY_LCTRL`            | `GLFW_KEY_LEFT_CONTROL`      |       |
| `GLFW_KEY_LSHIFT`           | `GLFW_KEY_LEFT_SHIFT`        |       |
| `GLFW_KEY_LALT`             | `GLFW_KEY_LEFT_ALT`          |       |
| `GLFW_KEY_LSUPER`           | `GLFW_KEY_LEFT_SUPER`        |       |
| `GLFW_KEY_RCTRL`            | `GLFW_KEY_RIGHT_CONTROL`     |       |
| `GLFW_KEY_RSHIFT`           | `GLFW_KEY_RIGHT_SHIFT`       |       |
| `GLFW_KEY_RALT`             | `GLFW_KEY_RIGHT_ALT`         |       |
| `GLFW_KEY_RSUPER`           | `GLFW_KEY_RIGHT_SUPER`       |       |

*/