33 KiB
Input guide
@tableofcontents
This guide introduces the input related functions of GLFW. For details on a specific function in this category, see the @ref input. There are also guides for the other areas of GLFW.
- @ref intro_guide
- @ref window_guide
- @ref context_guide
- @ref vulkan_guide
- @ref monitor_guide
GLFW provides many kinds of input. While some can only be polled, like time, or only received via callbacks, like scrolling, many provide both callbacks and polling. Callbacks are more work to use than polling but is less CPU intensive and guarantees that you do not miss state changes.
All input callbacks receive a window handle. By using the [window user pointer](@ref window_userptr), you can access non-global structures or objects from your callbacks.
To get a better feel for how the various events callbacks behave, run the
events test program. It registers every callback supported by GLFW and prints
out all arguments provided for every event, along with time and sequence
information.
Event processing
GLFW needs to poll the window system for events both to provide input to the application and to prove to the window system that the application hasn't locked up. Event processing is normally done each frame after [buffer swapping](@ref buffer_swap). Even when you have no windows, event polling needs to be done in order to receive monitor and joystick connection events.
There are three functions for processing pending events. @ref glfwPollEvents, processes only those events that have already been received and then returns immediately.
@code{.c} glfwPollEvents(); @endcode
This is the best choice when rendering continuously, like most games do.
If you only need to update the contents of the window when you receive new input, @ref glfwWaitEvents is a better choice.
@code{.c} glfwWaitEvents(); @endcode
It puts the thread to sleep until at least one event has been received and then processes all received events. This saves a great deal of CPU cycles and is useful for, for example, editing tools.
If you want to wait for events but have UI elements or other tasks that need periodic updates, @ref glfwWaitEventsTimeout lets you specify a timeout.
@code{.c} glfwWaitEventsTimeout(0.7); @endcode
It puts the thread to sleep until at least one event has been received, or until the specified number of seconds have elapsed. It then processes any received events.
If the main thread is sleeping in @ref glfwWaitEvents, you can wake it from another thread by posting an empty event to the event queue with @ref glfwPostEmptyEvent.
@code{.c} glfwPostEmptyEvent(); @endcode
Do not assume that callbacks will only be called in response to the above functions. While it is necessary to process events in one or more of the ways above, window systems that require GLFW to register callbacks of its own can pass events to GLFW in response to many window system function calls. GLFW will pass those events on to the application callbacks before returning.
For example, on Windows the system function that @ref glfwSetWindowSize is implemented with will send window size events directly to the event callback that every window has and that GLFW implements for its windows. If you have set a [window size callback](@ref window_size) GLFW will call it in turn with the new size before everything returns back out of the @ref glfwSetWindowSize call.
Keyboard input
GLFW divides keyboard input into two categories; key events and character events. Key events relate to actual physical keyboard keys, whereas character events relate to the text that is generated by pressing some of them.
Keys and characters do not map 1:1. A single key press may produce several characters, and a single character may require several keys to produce. This may not be the case on your machine, but your users are likely not all using the same keyboard layout, input method or even operating system as you.
Key input
If you wish to be notified when a physical key is pressed or released or when it repeats, set a key callback.
@code{.c} glfwSetKeyCallback(window, key_callback); @endcode
The callback function receives the [keyboard key](@ref keys), platform-specific scancode, key action and [modifier bits](@ref mods).
@code{.c} void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) { if (key == GLFW_KEY_E && action == GLFW_PRESS) activate_airship(); } @endcode
The action is one of GLFW_PRESS, GLFW_REPEAT or GLFW_RELEASE. Events with
GLFW_PRESS and GLFW_RELEASE actions are emitted for every key press. Most
keys will also emit events with GLFW_REPEAT actions while a key is held down.
Note that many keyboards have a limit on how many keys being simultaneous held down that they can detect. This limit is called key rollover.
Key events with GLFW_REPEAT actions are intended for text input. They are
emitted at the rate set in the user's keyboard settings. At most one key is
repeated even if several keys are held down. GLFW_REPEAT actions should not
be relied on to know which keys are being held down or to drive animation.
Instead you should either save the state of relevant keys based on GLFW_PRESS
and GLFW_RELEASE actions, or call @ref glfwGetKey, which provides basic cached
key state.
The key will be one of the existing [key tokens](@ref keys), or
GLFW_KEY_UNKNOWN if GLFW lacks a token for it, for example E-mail and Play
keys.
The scancode is unique for every key, regardless of whether it has a key token. Scancodes are platform-specific but consistent over time, so keys will have different scancodes depending on the platform but they are safe to save to disk. You can query the scancode for any [key token](@ref keys) supported on the current platform with @ref glfwGetKeyScancode.
@code{.c} const int scancode = glfwGetKeyScancode(GLFW_KEY_X); set_key_mapping(scancode, swap_weapons); @endcode
The last reported state for every physical key with a [key token](@ref keys) is also saved in per-window state arrays that can be polled with @ref glfwGetKey.
@code{.c} int state = glfwGetKey(window, GLFW_KEY_E); if (state == GLFW_PRESS) { activate_airship(); } @endcode
The returned state is one of GLFW_PRESS or GLFW_RELEASE.
This function only returns cached key event state. It does not poll the system for the current state of the physical key. It also does not provide any key repeat information.
@anchor GLFW_STICKY_KEYS
Whenever you poll state, you risk missing the state change you are looking for.
If a pressed key is released again before you poll its state, you will have
missed the key press. The recommended solution for this is to use a
key callback, but there is also the GLFW_STICKY_KEYS input mode.
@code{.c} glfwSetInputMode(window, GLFW_STICKY_KEYS, GLFW_TRUE); @endcode
When sticky keys mode is enabled, the pollable state of a key will remain
GLFW_PRESS until the state of that key is polled with @ref glfwGetKey. Once
it has been polled, if a key release event had been processed in the meantime,
the state will reset to GLFW_RELEASE, otherwise it will remain GLFW_PRESS.
@anchor GLFW_LOCK_KEY_MODS
If you wish to know what the state of the Caps Lock and Num Lock keys was when
input events were generated, set the GLFW_LOCK_KEY_MODS input mode.
@code{.c} glfwSetInputMode(window, GLFW_LOCK_KEY_MODS, GLFW_TRUE); @endcode
When this input mode is enabled, any callback that receives [modifier bits](@ref mods) will have the @ref GLFW_MOD_CAPS_LOCK bit set if Caps Lock was on when the event occurred and the @ref GLFW_MOD_NUM_LOCK bit set if Num Lock was on.
The GLFW_KEY_LAST constant holds the highest value of any
[key token](@ref keys).
Text input
GLFW supports text input in the form of a stream of Unicode code points, as produced by the operating system text input system. Unlike key input, text input is affected by keyboard layouts and modifier keys and supports composing characters using dead keys. Once received, you can encode the code points into UTF-8 or any other encoding you prefer.
Because an unsigned int is 32 bits long on all platforms supported by GLFW,
you can treat the code point argument as native endian UTF-32.
If you wish to offer regular text input, set a character callback.
@code{.c} glfwSetCharCallback(window, character_callback); @endcode
The callback function receives Unicode code points for key events that would have led to regular text input and generally behaves as a standard text field on that platform.
@code{.c} void character_callback(GLFWwindow* window, unsigned int codepoint) { } @endcode
Key names
If you wish to refer to keys by name, you can query the keyboard layout dependent name of printable keys with @ref glfwGetKeyName.
@code{.c} const char* key_name = glfwGetKeyName(GLFW_KEY_W, 0); show_tutorial_hint("Press %s to move forward", key_name); @endcode
This function can handle both [keys and scancodes](@ref input_key). If the
specified key is GLFW_KEY_UNKNOWN then the scancode is used, otherwise it is
ignored. This matches the behavior of the key callback, meaning the callback
arguments can always be passed unmodified to this function.
Mouse input
Mouse input comes in many forms, including mouse motion, button presses and scrolling offsets. The cursor appearance can also be changed, either to a custom image or a standard cursor shape from the system theme.
Cursor position
If you wish to be notified when the cursor moves over the window, set a cursor position callback.
@code{.c} glfwSetCursorPosCallback(window, cursor_position_callback); @endcode
The callback functions receives the cursor position, measured in screen coordinates but relative to the top-left corner of the window content area. On platforms that provide it, the full sub-pixel cursor position is passed on.
@code{.c} static void cursor_position_callback(GLFWwindow* window, double xpos, double ypos) { } @endcode
The cursor position is also saved per-window and can be polled with @ref glfwGetCursorPos.
@code{.c} double xpos, ypos; glfwGetCursorPos(window, &xpos, &ypos); @endcode
Cursor mode
@anchor GLFW_CURSOR
The GLFW_CURSOR input mode provides several cursor modes for special forms of
mouse motion input. By default, the cursor mode is GLFW_CURSOR_NORMAL,
meaning the regular arrow cursor (or another cursor set with @ref glfwSetCursor)
is used and cursor motion is not limited.
If you wish to implement mouse motion based camera controls or other input
schemes that require unlimited mouse movement, set the cursor mode to
GLFW_CURSOR_DISABLED.
@code{.c} glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); @endcode
This will hide the cursor and lock it to the specified window. GLFW will then take care of all the details of cursor re-centering and offset calculation and providing the application with a virtual cursor position. This virtual position is provided normally via both the cursor position callback and through polling.
@note You should not implement your own version of this functionality using
other features of GLFW. It is not supported and will not work as robustly as
GLFW_CURSOR_DISABLED.
If you only wish the cursor to become hidden when it is over a window but still
want it to behave normally, set the cursor mode to GLFW_CURSOR_HIDDEN.
@code{.c} glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_HIDDEN); @endcode
This mode puts no limit on the motion of the cursor.
If you wish the cursor to be visible but confined to the content area of the
window, set the cursor mode to GLFW_CURSOR_CAPTURED.
@code{.c} glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_CAPTURED); @endcode
The cursor will behave normally inside the content area but will not be able to leave unless the window loses focus.
To exit out of either of these special modes, restore the GLFW_CURSOR_NORMAL
cursor mode.
@code{.c} glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL); @endcode
If the cursor was disabled, this will move it back to its last visible position.
@anchor GLFW_RAW_MOUSE_MOTION
Raw mouse motion
When the cursor is disabled, raw (unscaled and unaccelerated) mouse motion can be enabled if available.
Raw mouse motion is closer to the actual motion of the mouse across a surface. It is not affected by the scaling and acceleration applied to the motion of the desktop cursor. That processing is suitable for a cursor while raw motion is better for controlling for example a 3D camera. Because of this, raw mouse motion is only provided when the cursor is disabled.
Call @ref glfwRawMouseMotionSupported to check if the current machine provides
raw motion and set the GLFW_RAW_MOUSE_MOTION input mode to enable it. It is
disabled by default.
@code{.c} if (glfwRawMouseMotionSupported()) glfwSetInputMode(window, GLFW_RAW_MOUSE_MOTION, GLFW_TRUE); @endcode
If supported, raw mouse motion can be enabled or disabled per-window and at any time but it will only be provided when the cursor is disabled.
Cursor objects
GLFW supports creating both custom and system theme cursor images, encapsulated as @ref GLFWcursor objects. They are created with @ref glfwCreateCursor or @ref glfwCreateStandardCursor and destroyed with @ref glfwDestroyCursor, or @ref glfwTerminate, if any remain.
Custom cursor creation
A custom cursor is created with @ref glfwCreateCursor, which returns a handle to the created cursor object. For example, this creates a 16x16 white square cursor with the hot-spot in the upper-left corner:
@code{.c} unsigned char pixels[16 * 16 * 4]; memset(pixels, 0xff, sizeof(pixels));
GLFWimage image; image.width = 16; image.height = 16; image.pixels = pixels;
GLFWcursor* cursor = glfwCreateCursor(&image, 0, 0); @endcode
If cursor creation fails, NULL will be returned, so it is necessary to check
the return value.
The image data is 32-bit, little-endian, non-premultiplied RGBA, i.e. eight bits per channel with the red channel first. The pixels are arranged canonically as sequential rows, starting from the top-left corner.
Standard cursor creation
A cursor with a [standard shape](@ref shapes) from the current system cursor theme can be created with @ref glfwCreateStandardCursor.
@code{.c} GLFWcursor* url_cursor = glfwCreateStandardCursor(GLFW_POINTING_HAND_CURSOR); @endcode
These cursor objects behave in the exact same way as those created with @ref glfwCreateCursor except that the system cursor theme provides the actual image.
A few of these shapes are not available everywhere. If a shape is unavailable,
NULL is returned. See @ref glfwCreateStandardCursor for details.
Cursor destruction
When a cursor is no longer needed, destroy it with @ref glfwDestroyCursor.
@code{.c} glfwDestroyCursor(cursor); @endcode
Cursor destruction always succeeds. If the cursor is current for any window, that window will revert to the default cursor. This does not affect the cursor mode. All remaining cursors are destroyed when @ref glfwTerminate is called.
Cursor setting
A cursor can be set as current for a window with @ref glfwSetCursor.
@code{.c} glfwSetCursor(window, cursor); @endcode
Once set, the cursor image will be used as long as the system cursor is over the
content area of the window and the [cursor mode](@ref cursor_mode) is set
to GLFW_CURSOR_NORMAL.
A single cursor may be set for any number of windows.
To revert to the default cursor, set the cursor of that window to NULL.
@code{.c} glfwSetCursor(window, NULL); @endcode
When a cursor is destroyed, any window that has it set will revert to the default cursor. This does not affect the cursor mode.
Cursor enter/leave events
If you wish to be notified when the cursor enters or leaves the content area of a window, set a cursor enter/leave callback.
@code{.c} glfwSetCursorEnterCallback(window, cursor_enter_callback); @endcode
The callback function receives the new classification of the cursor.
@code{.c} void cursor_enter_callback(GLFWwindow* window, int entered) { if (entered) { // The cursor entered the content area of the window } else { // The cursor left the content area of the window } } @endcode
You can query whether the cursor is currently inside the content area of the window with the [GLFW_HOVERED](@ref GLFW_HOVERED_attrib) window attribute.
@code{.c} if (glfwGetWindowAttrib(window, GLFW_HOVERED)) { highlight_interface(); } @endcode
Mouse button input
If you wish to be notified when a mouse button is pressed or released, set a mouse button callback.
@code{.c} glfwSetMouseButtonCallback(window, mouse_button_callback); @endcode
The callback function receives the [mouse button](@ref buttons), button action and [modifier bits](@ref mods).
@code{.c} void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) { if (button == GLFW_MOUSE_BUTTON_RIGHT && action == GLFW_PRESS) popup_menu(); } @endcode
The action is one of GLFW_PRESS or GLFW_RELEASE.
The last reported state for every [supported mouse button](@ref buttons) is also saved in per-window state arrays that can be polled with @ref glfwGetMouseButton.
@code{.c} int state = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT); if (state == GLFW_PRESS) { upgrade_cow(); } @endcode
The returned state is one of GLFW_PRESS or GLFW_RELEASE.
This function only returns cached mouse button event state. It does not poll the system for the current state of the mouse button.
@anchor GLFW_STICKY_MOUSE_BUTTONS
Whenever you poll state, you risk missing the state change you are looking for.
If a pressed mouse button is released again before you poll its state, you will have
missed the button press. The recommended solution for this is to use a
mouse button callback, but there is also the GLFW_STICKY_MOUSE_BUTTONS
input mode.
@code{.c} glfwSetInputMode(window, GLFW_STICKY_MOUSE_BUTTONS, GLFW_TRUE); @endcode
When sticky mouse buttons mode is enabled, the pollable state of a mouse button
will remain GLFW_PRESS until the state of that button is polled with @ref
glfwGetMouseButton. Once it has been polled, if a mouse button release event
had been processed in the meantime, the state will reset to GLFW_RELEASE,
otherwise it will remain GLFW_PRESS.
The GLFW_MOUSE_BUTTON_LAST constant holds the highest value of any
[supported mouse button](@ref buttons).
Scroll input
If you wish to be notified when the user scrolls, whether with a mouse wheel or touchpad gesture, set a scroll callback.
@code{.c} glfwSetScrollCallback(window, scroll_callback); @endcode
The callback function receives two-dimensional scroll offsets.
@code{.c} void scroll_callback(GLFWwindow* window, double xoffset, double yoffset) { } @endcode
A normal mouse wheel, being vertical, provides offsets along the Y-axis.
Joystick input
The joystick functions expose connected joysticks and controllers, with both
referred to as joysticks. It supports up to sixteen joysticks, ranging from
GLFW_JOYSTICK_1, GLFW_JOYSTICK_2 up to and including GLFW_JOYSTICK_16 or
GLFW_JOYSTICK_LAST. You can test whether a [joystick](@ref joysticks) is
present with @ref glfwJoystickPresent.
@code{.c} int present = glfwJoystickPresent(GLFW_JOYSTICK_1); @endcode
Each joystick has zero or more axes, zero or more buttons, zero or more hats, a human-readable name, a user pointer and an SDL compatible GUID.
Detected joysticks are added to the beginning of the array. Once a joystick is detected, it keeps its assigned ID until it is disconnected or the library is terminated, so as joysticks are connected and disconnected, there may appear gaps in the IDs.
Joystick axis, button and hat state is updated when polled and does not require a window to be created or events to be processed. However, if you want joystick connection and disconnection events reliably delivered to the [joystick callback](@ref joystick_event) then you must [process events](@ref events).
To see all the properties of all connected joysticks in real-time, run the
joysticks test program.
Joystick axis states
The positions of all axes of a joystick are returned by @ref glfwGetJoystickAxes. See the reference documentation for the lifetime of the returned array.
@code{.c} int count; const float* axes = glfwGetJoystickAxes(GLFW_JOYSTICK_5, &count); @endcode
Each element in the returned array is a value between -1.0 and 1.0.
Joystick button states
The states of all buttons of a joystick are returned by @ref glfwGetJoystickButtons. See the reference documentation for the lifetime of the returned array.
@code{.c} int count; const unsigned char* buttons = glfwGetJoystickButtons(GLFW_JOYSTICK_3, &count); @endcode
Each element in the returned array is either GLFW_PRESS or GLFW_RELEASE.
For backward compatibility with earlier versions that did not have @ref glfwGetJoystickHats, the button array by default also includes all hats. See the reference documentation for @ref glfwGetJoystickButtons for details.
Joystick hat states
The states of all hats are returned by @ref glfwGetJoystickHats. See the reference documentation for the lifetime of the returned array.
@code{.c} int count; const unsigned char* hats = glfwGetJoystickHats(GLFW_JOYSTICK_7, &count); @endcode
Each element in the returned array is one of the following:
| Name | Value |
|---|---|
GLFW_HAT_CENTERED |
0 |
GLFW_HAT_UP |
1 |
GLFW_HAT_RIGHT |
2 |
GLFW_HAT_DOWN |
4 |
GLFW_HAT_LEFT |
8 |
GLFW_HAT_RIGHT_UP |
GLFW_HAT_RIGHT | GLFW_HAT_UP |
GLFW_HAT_RIGHT_DOWN |
GLFW_HAT_RIGHT | GLFW_HAT_DOWN |
GLFW_HAT_LEFT_UP |
GLFW_HAT_LEFT | GLFW_HAT_UP |
GLFW_HAT_LEFT_DOWN |
GLFW_HAT_LEFT | GLFW_HAT_DOWN |
The diagonal directions are bitwise combinations of the primary (up, right, down and left) directions and you can test for these individually by ANDing it with the corresponding direction.
@code{.c} if (hats[2] & GLFW_HAT_RIGHT) { // State of hat 2 could be right-up, right or right-down } @endcode
For backward compatibility with earlier versions that did not have @ref glfwGetJoystickHats, all hats are by default also included in the button array. See the reference documentation for @ref glfwGetJoystickButtons for details.
Joystick name
The human-readable, UTF-8 encoded name of a joystick is returned by @ref glfwGetJoystickName. See the reference documentation for the lifetime of the returned string.
@code{.c} const char* name = glfwGetJoystickName(GLFW_JOYSTICK_4); @endcode
Joystick names are not guaranteed to be unique. Two joysticks of the same model and make may have the same name. Only the [joystick ID](@ref joysticks) is guaranteed to be unique, and only until that joystick is disconnected.
Joystick user pointer
Each joystick has a user pointer that can be set with @ref glfwSetJoystickUserPointer and queried with @ref glfwGetJoystickUserPointer. This can be used for any purpose you need and will not be modified by GLFW. The value will be kept until the joystick is disconnected or until the library is terminated.
The initial value of the pointer is NULL.
Joystick configuration changes
If you wish to be notified when a joystick is connected or disconnected, set a joystick callback.
@code{.c} glfwSetJoystickCallback(joystick_callback); @endcode
The callback function receives the ID of the joystick that has been connected and disconnected and the event that occurred.
@code{.c} void joystick_callback(int jid, int event) { if (event == GLFW_CONNECTED) { // The joystick was connected } else if (event == GLFW_DISCONNECTED) { // The joystick was disconnected } } @endcode
For joystick connection and disconnection events to be delivered on all platforms, you need to call one of the [event processing](@ref events) functions. Joystick disconnection may also be detected and the callback called by joystick functions. The function will then return whatever it returns for a disconnected joystick.
Only @ref glfwGetJoystickName and @ref glfwGetJoystickUserPointer will return useful values for a disconnected joystick and only before the monitor callback returns.
Gamepad input
The joystick functions provide unlabeled axes, buttons and hats, with no indication of where they are located on the device. Their order may also vary between platforms even with the same device.
To solve this problem the SDL community crowdsourced the SDL_GameControllerDB project, a database of mappings from many different devices to an Xbox-like gamepad.
GLFW supports this mapping format and contains a copy of the mappings available at the time of release. See @ref gamepad_mapping for how to update this at runtime. Mappings will be assigned to joysticks automatically any time a joystick is connected or the mappings are updated.
You can check whether a joystick is both present and has a gamepad mapping with @ref glfwJoystickIsGamepad.
@code{.c} if (glfwJoystickIsGamepad(GLFW_JOYSTICK_2)) { // Use as gamepad } @endcode
If you are only interested in gamepad input you can use this function instead of @ref glfwJoystickPresent.
You can query the human-readable name provided by the gamepad mapping with @ref glfwGetGamepadName. This may or may not be the same as the [joystick name](@ref joystick_name).
@code{.c} const char* name = glfwGetGamepadName(GLFW_JOYSTICK_7); @endcode
To retrieve the gamepad state of a joystick, call @ref glfwGetGamepadState.
@code{.c} GLFWgamepadstate state;
if (glfwGetGamepadState(GLFW_JOYSTICK_3, &state)) { if (state.buttons[GLFW_GAMEPAD_BUTTON_A]) { input_jump(); }
input_speed(state.axes[GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER]);
} @endcode
The @ref GLFWgamepadstate struct has two arrays; one for button states and one
for axis states. The values for each button and axis are the same as for the
@ref glfwGetJoystickButtons and @ref glfwGetJoystickAxes functions, i.e.
GLFW_PRESS or GLFW_RELEASE for buttons and -1.0 to 1.0 inclusive for axes.
The sizes of the arrays and the positions within each array are fixed.
The [button indices](@ref gamepad_buttons) are GLFW_GAMEPAD_BUTTON_A,
GLFW_GAMEPAD_BUTTON_B, GLFW_GAMEPAD_BUTTON_X, GLFW_GAMEPAD_BUTTON_Y,
GLFW_GAMEPAD_BUTTON_LEFT_BUMPER, GLFW_GAMEPAD_BUTTON_RIGHT_BUMPER,
GLFW_GAMEPAD_BUTTON_BACK, GLFW_GAMEPAD_BUTTON_START,
GLFW_GAMEPAD_BUTTON_GUIDE, GLFW_GAMEPAD_BUTTON_LEFT_THUMB,
GLFW_GAMEPAD_BUTTON_RIGHT_THUMB, GLFW_GAMEPAD_BUTTON_DPAD_UP,
GLFW_GAMEPAD_BUTTON_DPAD_RIGHT, GLFW_GAMEPAD_BUTTON_DPAD_DOWN and
GLFW_GAMEPAD_BUTTON_DPAD_LEFT.
For those who prefer, there are also the GLFW_GAMEPAD_BUTTON_CROSS,
GLFW_GAMEPAD_BUTTON_CIRCLE, GLFW_GAMEPAD_BUTTON_SQUARE and
GLFW_GAMEPAD_BUTTON_TRIANGLE aliases for the A, B, X and Y button indices.
The [axis indices](@ref gamepad_axes) are GLFW_GAMEPAD_AXIS_LEFT_X,
GLFW_GAMEPAD_AXIS_LEFT_Y, GLFW_GAMEPAD_AXIS_RIGHT_X,
GLFW_GAMEPAD_AXIS_RIGHT_Y, GLFW_GAMEPAD_AXIS_LEFT_TRIGGER and
GLFW_GAMEPAD_AXIS_RIGHT_TRIGGER.
The GLFW_GAMEPAD_BUTTON_LAST and GLFW_GAMEPAD_AXIS_LAST constants equal
the largest available index for each array.
Gamepad mappings
GLFW contains a copy of the mappings available in SDL_GameControllerDB at the time of release. Newer ones can be added at runtime with @ref glfwUpdateGamepadMappings.
@code{.c} const char* mappings = load_file_contents("game/data/gamecontrollerdb.txt");
glfwUpdateGamepadMappings(mappings); @endcode
This function supports everything from single lines up to and including the
unmodified contents of the whole gamecontrollerdb.txt file.
If you are compiling GLFW from source with CMake you can update the built-in mappings by
building the update_mappings target. This runs the GenerateMappings.cmake CMake
script, which downloads gamecontrollerdb.txt and regenerates the mappings.h header
file.
Below is a description of the mapping format. Please keep in mind that this description is not authoritative. The format is defined by the SDL and SDL_GameControllerDB projects and their documentation and code takes precedence.
Each mapping is a single line of comma-separated values describing the GUID, name and layout of the gamepad. Lines that do not begin with a hexadecimal digit are ignored.
The first value is always the gamepad GUID, a 32 character long hexadecimal string that typically identifies its make, model, revision and the type of connection to the computer. When this information is not available, the GUID is generated using the gamepad name. GLFW uses the SDL 2.0.5+ GUID format but can convert from the older formats.
The second value is always the human-readable name of the gamepad.
All subsequent values are in the form <field>:<value> and describe the layout
of the mapping. These fields may not all be present and may occur in any order.
The button fields are a, b, x, y, back, start, guide, dpup,
dpright, dpdown, dpleft, leftshoulder, rightshoulder, leftstick and
rightstick.
The axis fields are leftx, lefty, rightx, righty, lefttrigger and
righttrigger.
The value of an axis or button field can be a joystick button, a joystick axis,
a hat bitmask or empty. Joystick buttons are specified as bN, for example
b2 for the third button. Joystick axes are specified as aN, for example
a7 for the eighth button. Joystick hat bit masks are specified as hN.N, for
example h0.8 for left on the first hat. More than one bit may be set in the
mask.
Before an axis there may be a + or - range modifier, for example +a3 for
the positive half of the fourth axis. This restricts input to only the positive
or negative halves of the joystick axis. After an axis or half-axis there may
be the ~ inversion modifier, for example a2~ or -a7~. This negates the
values of the gamepad axis.
The hat bit mask match the [hat states](@ref hat_state) in the joystick functions.
There is also the special platform field that specifies which platform the
mapping is valid for. Possible values are Windows, Mac OS X and Linux.
Below is an example of what a gamepad mapping might look like. It is the one built into GLFW for Xbox controllers accessed via the XInput API on Windows. This example has been broken into several lines to fit on the page, but real gamepad mappings must be a single line.
@code{.unparsed} 78696e70757401000000000000000000,XInput Gamepad (GLFW),platform:Windows,a:b0, b:b1,x:b2,y:b3,leftshoulder:b4,rightshoulder:b5,back:b6,start:b7,leftstick:b8, rightstick:b9,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4, righttrigger:a5,dpup:h0.1,dpright:h0.2,dpdown:h0.4,dpleft:h0.8, @endcode
@note GLFW does not yet support the output range and modifiers + and - that
were recently added to SDL. The input modifiers +, - and ~ are supported
and described above.
Time input
GLFW provides high-resolution time input, in seconds, with @ref glfwGetTime.
@code{.c} double seconds = glfwGetTime(); @endcode
It returns the number of seconds since the library was initialized with @ref glfwInit. The platform-specific time sources used typically have micro- or nanosecond resolution.
You can modify the base time with @ref glfwSetTime.
@code{.c} glfwSetTime(4.0); @endcode
This sets the time to the specified time, in seconds, and it continues to count from there.
You can also access the raw timer used to implement the functions above, with @ref glfwGetTimerValue.
@code{.c} uint64_t value = glfwGetTimerValue(); @endcode
This value is in 1 / frequency seconds. The frequency of the raw timer varies depending on the operating system and hardware. You can query the frequency, in Hz, with @ref glfwGetTimerFrequency.
@code{.c} uint64_t frequency = glfwGetTimerFrequency(); @endcode
Clipboard input and output
If the system clipboard contains a UTF-8 encoded string or if it can be converted to one, you can retrieve it with @ref glfwGetClipboardString. See the reference documentation for the lifetime of the returned string.
@code{.c} const char* text = glfwGetClipboardString(NULL); if (text) { insert_text(text); } @endcode
If the clipboard is empty or if its contents could not be converted, NULL is
returned.
The contents of the system clipboard can be set to a UTF-8 encoded string with @ref glfwSetClipboardString.
@code{.c} glfwSetClipboardString(NULL, "A string with words in it"); @endcode
Path drop input
If you wish to receive the paths of files and/or directories dropped on a window, set a file drop callback.
@code{.c} glfwSetDropCallback(window, drop_callback); @endcode
The callback function receives an array of paths encoded as UTF-8.
@code{.c} void drop_callback(GLFWwindow* window, int count, const char** paths) { int i; for (i = 0; i < count; i++) handle_dropped_file(paths[i]); } @endcode
The path array and its strings are only valid until the file drop callback returns, as they may have been generated specifically for that event. You need to make a deep copy of the array if you want to keep the paths.