This guide introduces the window related functions of GLFW. For details on a specific function in this category, see the Window reference. There are also guides for the other areas of GLFW.
The GLFWwindow object encapsulates both a window and a context. They are created with glfwCreateWindow and destroyed with glfwDestroyWindow, or glfwTerminate, if any remain. As the window and context are inseparably linked, the object pointer is used as both a context and window handle.
To see the event stream provided to the various window related callbacks, run the events test program.
A window and its OpenGL or OpenGL ES context are created with glfwCreateWindow, which returns a handle to the created window object. For example, this creates a 640 by 480 windowed mode window:
If window creation fails, NULL will be returned, so it is necessary to check the return value.
The window handle is passed to all window related functions and is provided to along with all input events, so event handlers can tell which window received the event.
To create a full screen window, you need to specify which monitor the window should use. In most cases, the user's primary monitor is a good choice. For more information about retrieving monitors, see Retrieving monitors.
Full screen windows cover the entire display area of a monitor, have no border or decorations.
Windowed mode windows can be made full screen by setting a monitor with glfwSetWindowMonitor, and full screen ones can be made windowed by unsetting it with the same function.
Each field of the GLFWvidmode structure corresponds to a function parameter or window hint and combine to form the desired video mode for that window. The supported video mode most closely matching the desired video mode will be set for the chosen monitor as long as the window has input focus. For more information about retrieving video modes, see Video modes.
| Video mode field | Corresponds to |
|---|---|
| GLFWvidmode.width | width parameter of glfwCreateWindow |
| GLFWvidmode.height | height parameter of glfwCreateWindow |
| GLFWvidmode.redBits | GLFW_RED_BITS hint |
| GLFWvidmode.greenBits | GLFW_GREEN_BITS hint |
| GLFWvidmode.blueBits | GLFW_BLUE_BITS hint |
| GLFWvidmode.refreshRate | GLFW_REFRESH_RATE hint |
Once you have a full screen window, you can change its resolution, refresh rate and monitor with glfwSetWindowMonitor. If you only need change its resolution you can also call glfwSetWindowSize. In all cases, the new video mode will be selected the same way as the video mode chosen by glfwCreateWindow. If the window has an OpenGL or OpenGL ES context, it will be unaffected.
By default, the original video mode of the monitor will be restored and the window iconified if it loses input focus, to allow the user to switch back to the desktop. This behavior can be disabled with the GLFW_AUTO_ICONIFY window hint, for example if you wish to simultaneously cover multiple monitors with full screen windows.
If a monitor is disconnected, all windows that are full screen on that monitor will be switched to windowed mode. See Monitor configuration changes for more information.
If the closest match for the desired video mode is the current one, the video mode will not be changed, making window creation faster and application switching much smoother. This is sometimes called windowed full screen or borderless full screen window and counts as a full screen window. To create such a window, request the current video mode.
This also works for windowed mode windows that are made full screen.
Note that glfwGetVideoMode returns the current video mode of a monitor, so if you already have a full screen window on that monitor that you want to make windowed full screen, you need to have saved the desktop resolution before.
When a window is no longer needed, destroy it with glfwDestroyWindow.
Window destruction always succeeds. Before the actual destruction, all callbacks are removed so no further events will be delivered for the window. All windows remaining when glfwTerminate is called are destroyed as well.
When a full screen window is destroyed, the original video mode of its monitor is restored, but the gamma ramp is left untouched.
There are a number of hints that can be set before the creation of a window and context. Some affect the window itself, others affect the framebuffer or context. These hints are set to their default values each time the library is initialized with glfwInit. Integer value hints can be set individually with glfwWindowHint and string value hints with glfwWindowHintString. You can reset all at once to their defaults with glfwDefaultWindowHints.
Some hints are platform specific. These are always valid to set on any platform but they will only affect their specific platform. Other platforms will ignore them. Setting these hints requires no platform specific headers or calls.
Some window hints are hard constraints. These must match the available capabilities exactly for window and context creation to succeed. Hints that are not hard constraints are matched as closely as possible, but the resulting context and framebuffer may differ from what these hints requested.
The following hints are always hard constraints:
The following additional hints are hard constraints when requesting an OpenGL context, but are ignored when requesting an OpenGL ES context:
GLFW_RESIZABLE specifies whether the windowed mode window will be resizable by the user. The window will still be resizable using the glfwSetWindowSize function. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen and undecorated windows.
GLFW_VISIBLE specifies whether the windowed mode window will be initially visible. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen windows.
GLFW_DECORATED specifies whether the windowed mode window will have window decorations such as a border, a close widget, etc. An undecorated window will not be resizable by the user but will still allow the user to generate close events on some platforms. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen windows.
GLFW_FOCUSED specifies whether the windowed mode window will be given input focus when created. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen and initially hidden windows.
GLFW_AUTO_ICONIFY specifies whether the full screen window will automatically iconify and restore the previous video mode on input focus loss. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for windowed mode windows.
GLFW_FLOATING specifies whether the windowed mode window will be floating above other regular windows, also called topmost or always-on-top. This is intended primarily for debugging purposes and cannot be used to implement proper full screen windows. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen windows.
GLFW_MAXIMIZED specifies whether the windowed mode window will be maximized when created. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for full screen windows.
GLFW_CENTER_CURSOR specifies whether the cursor should be centered over newly created full screen windows. Possible values are GLFW_TRUE and GLFW_FALSE. This hint is ignored for windowed mode windows.
GLFW_TRANSPARENT_FRAMEBUFFER specifies whether the window framebuffer will be transparent. If enabled and supported by the system, the window framebuffer alpha channel will be used to combine the framebuffer with the background. This does not affect window decorations. Possible values are GLFW_TRUE and GLFW_FALSE.
GLFW_FOCUS_ON_SHOW specifies whether the window will be given input focus when glfwShowWindow is called. Possible values are GLFW_TRUE and GLFW_FALSE.
GLFW_SCALE_TO_MONITOR specified whether the window content area should be resized based on content scale changes. This can be because of a global user settings change or because the window was moved to a monitor with different scale settings.
This hint only has an effect on platforms where screen coordinates and pixels always map 1:1, such as Windows and X11. On platforms like macOS the resolution of the framebuffer can change independently of the window size.
GLFW_SCALE_FRAMEBUFFER specifies whether the framebuffer should be resized based on content scale changes. This can be because of a global user settings change or because the window was moved to a monitor with different scale settings.
This hint only has an effect on platforms where screen coordinates can be scaled relative to pixel coordinates, such as macOS and Wayland. On platforms like Windows and X11 the framebuffer and window content area sizes always map 1:1.
This is the new name, introduced in GLFW 3.4. The older GLFW_COCOA_RETINA_FRAMEBUFFER name is also available for compatibility. Both names modify the same hint value.
GLFW_MOUSE_PASSTHROUGH specifies whether the window is transparent to mouse input, letting any mouse events pass through to whatever window is behind it. This is only supported for undecorated windows. Decorated windows with this enabled will behave differently between platforms. Possible values are GLFW_TRUE and GLFW_FALSE.
GLFW_POSITION_X and GLFW_POSITION_Y specify the desired initial position of the window. The window manager may modify or ignore these coordinates. If either or both of these hints are set to GLFW_ANY_POSITION then the window manager will position the window where it thinks the user will prefer it. Possible values are any valid screen coordinates and GLFW_ANY_POSITION.
GLFW_RED_BITS, GLFW_GREEN_BITS, GLFW_BLUE_BITS, GLFW_ALPHA_BITS, GLFW_DEPTH_BITS and GLFW_STENCIL_BITS specify the desired bit depths of the various components of the default framebuffer. A value of GLFW_DONT_CARE means the application has no preference.
GLFW_ACCUM_RED_BITS, GLFW_ACCUM_GREEN_BITS, GLFW_ACCUM_BLUE_BITS and GLFW_ACCUM_ALPHA_BITS specify the desired bit depths of the various components of the accumulation buffer. A value of GLFW_DONT_CARE means the application has no preference.
Accumulation buffers are a legacy OpenGL feature and should not be used in new code.
GLFW_AUX_BUFFERS specifies the desired number of auxiliary buffers. A value of GLFW_DONT_CARE means the application has no preference.
Auxiliary buffers are a legacy OpenGL feature and should not be used in new code.
GLFW_STEREO specifies whether to use OpenGL stereoscopic rendering. Possible values are GLFW_TRUE and GLFW_FALSE. This is a hard constraint.
GLFW_SAMPLES specifies the desired number of samples to use for multisampling. Zero disables multisampling. A value of GLFW_DONT_CARE means the application has no preference.
GLFW_SRGB_CAPABLE specifies whether the framebuffer should be sRGB capable. Possible values are GLFW_TRUE and GLFW_FALSE.
GL_FRAMEBUFFER_SRGB enable will control sRGB rendering. By default, sRGB rendering will be disabled.GLFW_DOUBLEBUFFER specifies whether the framebuffer should be double buffered. You nearly always want to use double buffering. This is a hard constraint. Possible values are GLFW_TRUE and GLFW_FALSE.
GLFW_REFRESH_RATE specifies the desired refresh rate for full screen windows. A value of GLFW_DONT_CARE means the highest available refresh rate will be used. This hint is ignored for windowed mode windows.
GLFW_CLIENT_API specifies which client API to create the context for. Possible values are GLFW_OPENGL_API, GLFW_OPENGL_ES_API and GLFW_NO_API. This is a hard constraint.
GLFW_CONTEXT_CREATION_API specifies which context creation API to use to create the context. Possible values are GLFW_NATIVE_CONTEXT_API, GLFW_EGL_CONTEXT_API and GLFW_OSMESA_CONTEXT_API. This is a hard constraint. If no client API is requested, this hint is ignored.
An extension loader library that assumes it knows which API was used to create the current context may fail if you change this hint. This can be resolved by having it load functions via glfwGetProcAddress.
GLFW_CONTEXT_VERSION_MAJOR and GLFW_CONTEXT_VERSION_MINOR specify the client API version that the created context must be compatible with. The exact behavior of these hints depend on the requested client API.
While there is no way to ask the driver for a context of the highest supported version, GLFW will attempt to provide this when you ask for a version 1.0 context, which is the default for these hints.
Do not confuse these hints with GLFW_VERSION_MAJOR and GLFW_VERSION_MINOR, which provide the API version of the GLFW header.
GLFW_OPENGL_FORWARD_COMPAT specifies whether the OpenGL context should be forward-compatible, i.e. one where all functionality deprecated in the requested version of OpenGL is removed. This must only be used if the requested OpenGL version is 3.0 or above. If OpenGL ES is requested, this hint is ignored.
Forward-compatibility is described in detail in the OpenGL Reference Manual.
GLFW_CONTEXT_DEBUG specifies whether the context should be created in debug mode, which may provide additional error and diagnostic reporting functionality. Possible values are GLFW_TRUE and GLFW_FALSE.
Debug contexts for OpenGL and OpenGL ES are described in detail by the GL_KHR_debug extension.
GLFW_CONTEXT_DEBUG is the new name introduced in GLFW 3.4. The older GLFW_OPENGL_DEBUG_CONTEXT name is also available for compatibility.GLFW_OPENGL_PROFILE specifies which OpenGL profile to create the context for. Possible values are one of GLFW_OPENGL_CORE_PROFILE or GLFW_OPENGL_COMPAT_PROFILE, or GLFW_OPENGL_ANY_PROFILE to not request a specific profile. If requesting an OpenGL version below 3.2, GLFW_OPENGL_ANY_PROFILE must be used. If OpenGL ES is requested, this hint is ignored.
OpenGL profiles are described in detail in the OpenGL Reference Manual.
GLFW_CONTEXT_ROBUSTNESS specifies the robustness strategy to be used by the context. This can be one of GLFW_NO_RESET_NOTIFICATION or GLFW_LOSE_CONTEXT_ON_RESET, or GLFW_NO_ROBUSTNESS to not request a robustness strategy.
GLFW_CONTEXT_RELEASE_BEHAVIOR specifies the release behavior to be used by the context. Possible values are one of GLFW_ANY_RELEASE_BEHAVIOR, GLFW_RELEASE_BEHAVIOR_FLUSH or GLFW_RELEASE_BEHAVIOR_NONE. If the behavior is GLFW_ANY_RELEASE_BEHAVIOR, the default behavior of the context creation API will be used. If the behavior is GLFW_RELEASE_BEHAVIOR_FLUSH, the pipeline will be flushed whenever the context is released from being the current one. If the behavior is GLFW_RELEASE_BEHAVIOR_NONE, the pipeline will not be flushed on release.
Context release behaviors are described in detail by the GL_KHR_context_flush_control extension.
GLFW_CONTEXT_NO_ERROR specifies whether errors should be generated by the context. Possible values are GLFW_TRUE and GLFW_FALSE. If enabled, situations that would have generated errors instead cause undefined behavior.
The no error mode for OpenGL and OpenGL ES is described in detail by the GL_KHR_no_error extension.
GLFW_WIN32_KEYBOARD_MENU specifies whether to allow access to the window menu via the Alt+Space and Alt-and-then-Space keyboard shortcuts. This is ignored on other platforms.
GLFW_WIN32_SHOWDEFAULT specifies whether to show the window the way specified in the program's STARTUPINFO when it is shown for the first time. This is the same information as the Run option in the shortcut properties window. If this information was not specified when the program was started, GLFW behaves as if this hint was set to GLFW_FALSE. Possible values are GLFW_TRUE and GLFW_FALSE. This is ignored on other platforms.
GLFW_COCOA_FRAME_NAME specifies the UTF-8 encoded name to use for autosaving the window frame, or if empty disables frame autosaving for the window. This is ignored on other platforms. This is set with glfwWindowHintString.
GLFW_COCOA_GRAPHICS_SWITCHING specifies whether to in Automatic Graphics Switching, i.e. to allow the system to choose the integrated GPU for the OpenGL context and move it between GPUs if necessary or whether to force it to always run on the discrete GPU. This only affects systems with both integrated and discrete GPUs. Possible values are GLFW_TRUE and GLFW_FALSE. This is ignored on other platforms.
Simpler programs and tools may want to enable this to save power, while games and other applications performing advanced rendering will want to leave it disabled.
A bundled application that wishes to participate in Automatic Graphics Switching should also declare this in its Info.plist by setting the NSSupportsAutomaticGraphicsSwitching key to true.
GLFW_WAYLAND_APP_ID specifies the Wayland app_id for a window, used by window managers to identify types of windows. This is set with glfwWindowHintString.
GLFW_X11_CLASS_NAME and GLFW_X11_INSTANCE_NAME specifies the desired ASCII encoded class and instance parts of the ICCCM WM_CLASS window property. Both hints need to be set to something other than an empty string for them to take effect. These are set with glfwWindowHintString.
| Window hint | Default value | Supported values |
|---|---|---|
| GLFW_RESIZABLE | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_VISIBLE | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_DECORATED | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_FOCUSED | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_AUTO_ICONIFY | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_FLOATING | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_MAXIMIZED | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_CENTER_CURSOR | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_TRANSPARENT_FRAMEBUFFER | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_FOCUS_ON_SHOW | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_SCALE_TO_MONITOR | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_SCALE_FRAMEBUFFER | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_MOUSE_PASSTHROUGH | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_POSITION_X | GLFW_ANY_POSITION | Any valid screen x-coordinate or GLFW_ANY_POSITION |
| GLFW_POSITION_Y | GLFW_ANY_POSITION | Any valid screen y-coordinate or GLFW_ANY_POSITION |
| GLFW_RED_BITS | 8 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_GREEN_BITS | 8 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_BLUE_BITS | 8 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_ALPHA_BITS | 8 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_DEPTH_BITS | 24 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_STENCIL_BITS | 8 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_ACCUM_RED_BITS | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_ACCUM_GREEN_BITS | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_ACCUM_BLUE_BITS | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_ACCUM_ALPHA_BITS | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_AUX_BUFFERS | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_SAMPLES | 0 | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_REFRESH_RATE | GLFW_DONT_CARE | 0 to INT_MAX or GLFW_DONT_CARE |
| GLFW_STEREO | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_SRGB_CAPABLE | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_DOUBLEBUFFER | GLFW_TRUE | GLFW_TRUE or GLFW_FALSE |
| GLFW_CLIENT_API | GLFW_OPENGL_API | GLFW_OPENGL_API, GLFW_OPENGL_ES_API or GLFW_NO_API |
| GLFW_CONTEXT_CREATION_API | GLFW_NATIVE_CONTEXT_API | GLFW_NATIVE_CONTEXT_API, GLFW_EGL_CONTEXT_API or GLFW_OSMESA_CONTEXT_API |
| GLFW_CONTEXT_VERSION_MAJOR | 1 | Any valid major version number of the chosen client API |
| GLFW_CONTEXT_VERSION_MINOR | 0 | Any valid minor version number of the chosen client API |
| GLFW_CONTEXT_ROBUSTNESS | GLFW_NO_ROBUSTNESS | GLFW_NO_ROBUSTNESS, GLFW_NO_RESET_NOTIFICATION or GLFW_LOSE_CONTEXT_ON_RESET |
| GLFW_CONTEXT_RELEASE_BEHAVIOR | GLFW_ANY_RELEASE_BEHAVIOR | GLFW_ANY_RELEASE_BEHAVIOR, GLFW_RELEASE_BEHAVIOR_FLUSH or GLFW_RELEASE_BEHAVIOR_NONE |
| GLFW_OPENGL_FORWARD_COMPAT | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_CONTEXT_DEBUG | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_OPENGL_PROFILE | GLFW_OPENGL_ANY_PROFILE | GLFW_OPENGL_ANY_PROFILE, GLFW_OPENGL_COMPAT_PROFILE or GLFW_OPENGL_CORE_PROFILE |
| GLFW_WIN32_KEYBOARD_MENU | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_WIN32_SHOWDEFAULT | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_COCOA_FRAME_NAME | "" | A UTF-8 encoded frame autosave name |
| GLFW_COCOA_GRAPHICS_SWITCHING | GLFW_FALSE | GLFW_TRUE or GLFW_FALSE |
| GLFW_WAYLAND_APP_ID | "" | An ASCII encoded Wayland app_id name |
| GLFW_X11_CLASS_NAME | "" | An ASCII encoded WM_CLASS class name |
| GLFW_X11_INSTANCE_NAME | "" | An ASCII encoded WM_CLASS instance name |
See Event processing.
Each window has a user pointer that can be set with glfwSetWindowUserPointer and queried with glfwGetWindowUserPointer. This can be used for any purpose you need and will not be modified by GLFW throughout the life-time of the window.
The initial value of the pointer is NULL.
When the user attempts to close the window, for example by clicking the close widget or using a key chord like Alt+F4, the close flag of the window is set. The window is however not actually destroyed and, unless you watch for this state change, nothing further happens.
The current state of the close flag is returned by glfwWindowShouldClose and can be set or cleared directly with glfwSetWindowShouldClose. A common pattern is to use the close flag as a main loop condition.
If you wish to be notified when the user attempts to close a window, set a close callback.
The callback function is called directly after the close flag has been set. It can be used for example to filter close requests and clear the close flag again unless certain conditions are met.
The size of a window can be changed with glfwSetWindowSize. For windowed mode windows, this sets the size, in screen coordinates of the content area or content area of the window. The window system may impose limits on window size.
For full screen windows, the specified size becomes the new resolution of the window's desired video mode. The video mode most closely matching the new desired video mode is set immediately. The window is resized to fit the resolution of the set video mode.
If you wish to be notified when a window is resized, whether by the user, the system or your own code, set a size callback.
The callback function receives the new size, in screen coordinates, of the content area of the window when the window is resized.
There is also glfwGetWindowSize for directly retrieving the current size of a window.
glViewport or other pixel-based OpenGL calls. The window size is in screen coordinates, not pixels. Use the framebuffer size, which is in pixels, for pixel-based calls.The above functions work with the size of the content area, but decorated windows typically have title bars and window frames around this rectangle. You can retrieve the extents of these with glfwGetWindowFrameSize.
The returned values are the distances, in screen coordinates, from the edges of the content area to the corresponding edges of the full window. As they are distances and not coordinates, they are always zero or positive.
While the size of a window is measured in screen coordinates, OpenGL works with pixels. The size you pass into glViewport, for example, should be in pixels. On some machines screen coordinates and pixels are the same, but on others they will not be. There is a second set of functions to retrieve the size, in pixels, of the framebuffer of a window.
If you wish to be notified when the framebuffer of a window is resized, whether by the user or the system, set a size callback.
The callback function receives the new size of the framebuffer when it is resized, which can for example be used to update the OpenGL viewport.
There is also glfwGetFramebufferSize for directly retrieving the current size of the framebuffer of a window.
The size of a framebuffer may change independently of the size of a window, for example if the window is dragged between a regular monitor and a high-DPI one.
The content scale for a window can be retrieved with glfwGetWindowContentScale.
The content scale can be thought of as the ratio between the current DPI and the platform's default DPI. It is intended to be a scaling factor to apply to the pixel dimensions of text and other UI elements. If the dimensions scaled by this factor looks appropriate on your machine then it should appear at a reasonable size on other machines with different DPI and scaling settings.
This relies on the DPI and scaling settings on both machines being appropriate.
The content scale may depend on both the monitor resolution and pixel density and on user settings like DPI or a scaling percentage. It may be very different from the raw DPI calculated from the physical size and current resolution.
On systems where each monitors can have its own content scale, the window content scale will depend on which monitor or monitors the system considers the window to be "on".
If you wish to be notified when the content scale of a window changes, whether because of a system setting change or because it was moved to a monitor with a different scale, set a content scale callback.
The callback function receives the new content scale of the window.
On platforms where pixels and screen coordinates always map 1:1, the window will need to be resized to appear the same size when it is moved to a monitor with a different content scale. To have this done automatically both when the window is created and when its content scale later changes, set the GLFW_SCALE_TO_MONITOR window hint.
On platforms where pixels do not necessarily equal screen coordinates, the framebuffer will instead need to be sized to provide a full resolution image for the window. When the window moves between monitors with different content scales, the window size will remain the same but the framebuffer size will change. This is done automatically by default. To disable this resizing, set the GLFW_SCALE_FRAMEBUFFER window hint.
Both of these hints also apply when the window is created. Every window starts out with a content scale of one. A window with one or both of these hints set will adapt to the appropriate scale in the process of being created, set up and shown.
The minimum and maximum size of the content area of a windowed mode window can be enforced with glfwSetWindowSizeLimits. The user may resize the window to any size and aspect ratio within the specified limits, unless the aspect ratio is also set.
To specify only a minimum size or only a maximum one, set the other pair to GLFW_DONT_CARE.
To disable size limits for a window, set them all to GLFW_DONT_CARE.
The aspect ratio of the content area of a windowed mode window can be enforced with glfwSetWindowAspectRatio. The user may resize the window freely unless size limits are also set, but the size will be constrained to maintain the aspect ratio.
The aspect ratio is specified as a numerator and denominator, corresponding to the width and height, respectively. If you want a window to maintain its current aspect ratio, use its current size as the ratio.
To disable the aspect ratio limit for a window, set both terms to GLFW_DONT_CARE.
You can have both size limits and aspect ratio set for a window, but the results are undefined if they conflict.
By default, the window manager chooses the position of new windowed mode windows, based on its size and which monitor the user appears to be working on. This is most often the right choice. If you need to create a window at a specific position, you can set the desired position with the GLFW_POSITION_X and GLFW_POSITION_Y window hints.
To restore the previous behavior, set these hints to GLFW_ANY_POSITION.
The position of a windowed mode window can be changed with glfwSetWindowPos. This moves the window so that the upper-left corner of its content area has the specified screen coordinates. The window system may put limitations on window placement.
If you wish to be notified when a window is moved, whether by the user, the system or your own code, set a position callback.
The callback function receives the new position, in screen coordinates, of the upper-left corner of the content area when the window is moved.
There is also glfwGetWindowPos for directly retrieving the current position of the content area of the window.
All GLFW windows have a title, although undecorated or full screen windows may not display it or only display it in a task bar or similar interface. You can set a new UTF-8 encoded window title with glfwSetWindowTitle.
The specified string is copied before the function returns, so there is no need to keep it around.
As long as your source file is encoded as UTF-8, you can use any Unicode characters directly in the source.
If you are using C++11 or C11, you can use a UTF-8 string literal.
The current window title can be queried with glfwGetWindowTitle.
Decorated windows have icons on some platforms. You can set this icon by specifying a list of candidate images with glfwSetWindowIcon.
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.
To revert to the default window icon, pass in an empty image array.
Full screen windows are associated with a specific monitor. You can get the handle for this monitor with glfwGetWindowMonitor.
This monitor handle is one of those returned by glfwGetMonitors.
For windowed mode windows, this function returns NULL. This is how to tell full screen windows from windowed mode windows.
You can move windows between monitors or between full screen and windowed mode with glfwSetWindowMonitor. When making a window full screen on the same or on a different monitor, specify the desired monitor, resolution and refresh rate. The position arguments are ignored.
When making the window windowed, specify the desired position and size. The refresh rate argument is ignored.
This restores any previous window settings such as whether it is decorated, floating, resizable, has size or aspect ratio limits, etc.. To restore a window that was originally windowed to its original size and position, save these before making it full screen and then pass them in as above.
Windows can be iconified (i.e. minimized) with glfwIconifyWindow.
When a full screen window is iconified, the original video mode of its monitor is restored until the user or application restores the window.
Iconified windows can be restored with glfwRestoreWindow. This function also restores windows from maximization.
When a full screen window is restored, the desired video mode is restored to its monitor as well.
If you wish to be notified when a window is iconified or restored, whether by the user, system or your own code, set an iconify callback.
The callback function receives changes in the iconification state of the window.
You can also get the current iconification state with glfwGetWindowAttrib.
Windows can be maximized (i.e. zoomed) with glfwMaximizeWindow.
Full screen windows cannot be maximized and passing a full screen window to this function does nothing.
Maximized windows can be restored with glfwRestoreWindow. This function also restores windows from iconification.
If you wish to be notified when a window is maximized or restored, whether by the user, system or your own code, set a maximize callback.
The callback function receives changes in the maximization state of the window.
You can also get the current maximization state with glfwGetWindowAttrib.
By default, newly created windows are not maximized. You can change this behavior by setting the GLFW_MAXIMIZED window hint before creating the window.
Windowed mode windows can be hidden with glfwHideWindow.
This makes the window completely invisible to the user, including removing it from the task bar, dock or window list. Full screen windows cannot be hidden and calling glfwHideWindow on a full screen window does nothing.
Hidden windows can be shown with glfwShowWindow.
By default, this function will also set the input focus to that window. Set the GLFW_FOCUS_ON_SHOW window hint to change this behavior for all newly created windows, or change the behavior for an existing window with glfwSetWindowAttrib.
You can also get the current visibility state with glfwGetWindowAttrib.
By default, newly created windows are visible. You can change this behavior by setting the GLFW_VISIBLE window hint before creating the window.
Windows created hidden are completely invisible to the user until shown. This can be useful if you need to set up your window further before showing it, for example moving it to a specific location.
Windows can be given input focus and brought to the front with glfwFocusWindow.
Keep in mind that it can be very disruptive to the user when a window is forced to the top. For a less disruptive way of getting the user's attention, see attention requests.
If you wish to be notified when a window gains or loses input focus, whether by the user, system or your own code, set a focus callback.
The callback function receives changes in the input focus state of the window.
You can also get the current input focus state with glfwGetWindowAttrib.
By default, newly created windows are given input focus. You can change this behavior by setting the GLFW_FOCUSED window hint before creating the window.
If you wish to notify the user of an event without interrupting, you can request attention with glfwRequestWindowAttention.
The system will highlight the specified window, or on platforms where this is not supported, the application as a whole. Once the user has given it attention, the system will automatically end the request.
If you wish to be notified when the contents of a window is damaged and needs to be refreshed, set a window refresh callback.
The callback function is called when the contents of the window needs to be refreshed.
GLFW supports two kinds of transparency for windows; framebuffer transparency and whole window transparency. A single window may not use both methods. The results of doing this are undefined.
Both methods require the platform to support it and not every version of every platform GLFW supports does this, so there are mechanisms to check whether the window really is transparent.
Window framebuffers can be made transparent on a per-pixel per-frame basis with the GLFW_TRANSPARENT_FRAMEBUFFER window hint.
If supported by the system, the window content area will be composited with the background using the framebuffer per-pixel alpha channel. This requires desktop compositing to be enabled on the system. It does not affect window decorations.
You can check whether the window framebuffer was successfully made transparent with the GLFW_TRANSPARENT_FRAMEBUFFER window attribute.
GLFW comes with an example that enabled framebuffer transparency called gears.
The opacity of the whole window, including any decorations, can be set with glfwSetWindowOpacity.
The opacity (or alpha) value is a positive finite number between zero and one, where 0 (zero) is fully transparent and 1 (one) is fully opaque. The initial opacity value for newly created windows is 1.
The current opacity of a window can be queried with glfwGetWindowOpacity.
If the system does not support whole window transparency, this function always returns one.
GLFW comes with a test program that lets you control whole window transparency at run-time called window.
If you want to use either of these transparency methods to display a temporary overlay like for example a notification, the GLFW_FLOATING and GLFW_MOUSE_PASSTHROUGH window hints and attributes may be useful.
Windows have a number of attributes that can be returned using glfwGetWindowAttrib. Some reflect state that may change as a result of user interaction, (e.g. whether it has input focus), while others reflect inherent properties of the window (e.g. what kind of border it has). Some are related to the window and others to its OpenGL or OpenGL ES context.
The GLFW_DECORATED, GLFW_RESIZABLE, GLFW_FLOATING, GLFW_AUTO_ICONIFY and GLFW_FOCUS_ON_SHOW window attributes can be changed with glfwSetWindowAttrib.
GLFW_FOCUSED indicates whether the specified window has input focus. See Window input focus for details.
GLFW_ICONIFIED indicates whether the specified window is iconified. See Window iconification for details.
GLFW_MAXIMIZED indicates whether the specified window is maximized. See Window maximization for details.
GLFW_HOVERED indicates whether the cursor is currently directly over the content area of the window, with no other windows between. See Cursor enter/leave events for details.
GLFW_VISIBLE indicates whether the specified window is visible. See Window visibility for details.
GLFW_RESIZABLE indicates whether the specified window is resizable by the user. This can be set before creation with the GLFW_RESIZABLE window hint or after with glfwSetWindowAttrib.
GLFW_DECORATED indicates whether the specified window has decorations such as a border, a close widget, etc. This can be set before creation with the GLFW_DECORATED window hint or after with glfwSetWindowAttrib.
GLFW_AUTO_ICONIFY indicates whether the specified full screen window is iconified on focus loss, a close widget, etc. This can be set before creation with the GLFW_AUTO_ICONIFY window hint or after with glfwSetWindowAttrib.
GLFW_FLOATING indicates whether the specified window is floating, also called topmost or always-on-top. This can be set before creation with the GLFW_FLOATING window hint or after with glfwSetWindowAttrib.
GLFW_TRANSPARENT_FRAMEBUFFER indicates whether the specified window has a transparent framebuffer, i.e. the window contents is composited with the background using the window framebuffer alpha channel. See Window transparency for details.
GLFW_FOCUS_ON_SHOW specifies whether the window will be given input focus when glfwShowWindow is called. This can be set before creation with the GLFW_FOCUS_ON_SHOW window hint or after with glfwSetWindowAttrib.
GLFW_MOUSE_PASSTHROUGH specifies whether the window is transparent to mouse input, letting any mouse events pass through to whatever window is behind it. This can be set before creation with the GLFW_MOUSE_PASSTHROUGH window hint or after with glfwSetWindowAttrib. This is only supported for undecorated windows. Decorated windows with this enabled will behave differently between platforms.
GLFW_CLIENT_API indicates the client API provided by the window's context; either GLFW_OPENGL_API, GLFW_OPENGL_ES_API or GLFW_NO_API.
GLFW_CONTEXT_CREATION_API indicates the context creation API used to create the window's context; either GLFW_NATIVE_CONTEXT_API, GLFW_EGL_CONTEXT_API or GLFW_OSMESA_CONTEXT_API.
GLFW_CONTEXT_VERSION_MAJOR, GLFW_CONTEXT_VERSION_MINOR and GLFW_CONTEXT_REVISION indicate the client API version of the window's context.
GLFW_VERSION_MAJOR, GLFW_VERSION_MINOR and GLFW_VERSION_REVISION which provide the API version of the GLFW header.GLFW_OPENGL_FORWARD_COMPAT is GLFW_TRUE if the window's context is an OpenGL forward-compatible one, or GLFW_FALSE otherwise.
GLFW_CONTEXT_DEBUG is GLFW_TRUE if the window's context is in debug mode, or GLFW_FALSE otherwise.
This is the new name, introduced in GLFW 3.4. The older GLFW_OPENGL_DEBUG_CONTEXT name is also available for compatibility.
GLFW_OPENGL_PROFILE indicates the OpenGL profile used by the context. This is GLFW_OPENGL_CORE_PROFILE or GLFW_OPENGL_COMPAT_PROFILE if the context uses a known profile, or GLFW_OPENGL_ANY_PROFILE if the OpenGL profile is unknown or the context is an OpenGL ES context. Note that the returned profile may not match the profile bits of the context flags, as GLFW will try other means of detecting the profile when no bits are set.
GLFW_CONTEXT_RELEASE_BEHAVIOR indicates the release used by the context. Possible values are one of GLFW_ANY_RELEASE_BEHAVIOR, GLFW_RELEASE_BEHAVIOR_FLUSH or GLFW_RELEASE_BEHAVIOR_NONE. If the behavior is GLFW_ANY_RELEASE_BEHAVIOR, the default behavior of the context creation API will be used. If the behavior is GLFW_RELEASE_BEHAVIOR_FLUSH, the pipeline will be flushed whenever the context is released from being the current one. If the behavior is GLFW_RELEASE_BEHAVIOR_NONE, the pipeline will not be flushed on release.
GLFW_CONTEXT_NO_ERROR indicates whether errors are generated by the context. Possible values are GLFW_TRUE and GLFW_FALSE. If enabled, situations that would have generated errors instead cause undefined behavior.
GLFW_CONTEXT_ROBUSTNESS indicates the robustness strategy used by the context. This is GLFW_LOSE_CONTEXT_ON_RESET or GLFW_NO_RESET_NOTIFICATION if the window's context supports robustness, or GLFW_NO_ROBUSTNESS otherwise.
GLFW does not expose most attributes of the default framebuffer (i.e. the framebuffer attached to the window) as these can be queried directly with either OpenGL, OpenGL ES or Vulkan. The one exception is GLFW_DOUBLEBUFFER, as this is not provided by OpenGL ES.
If you are using version 3.0 or later of OpenGL or OpenGL ES, the glGetFramebufferAttachmentParameteriv function can be used to retrieve the number of bits for the red, green, blue, alpha, depth and stencil buffer channels. Otherwise, the glGetIntegerv function can be used.
The number of MSAA samples are always retrieved with glGetIntegerv. For contexts supporting framebuffer objects, the number of samples of the currently bound framebuffer is returned.
| Attribute | glGetIntegerv | glGetFramebufferAttachmentParameteriv |
|---|---|---|
| Red bits | GL_RED_BITS | GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE |
| Green bits | GL_GREEN_BITS | GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE |
| Blue bits | GL_BLUE_BITS | GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE |
| Alpha bits | GL_ALPHA_BITS | GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE |
| Depth bits | GL_DEPTH_BITS | GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE |
| Stencil bits | GL_STENCIL_BITS | GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE |
| MSAA samples | GL_SAMPLES | Not provided by this function |
When calling glGetFramebufferAttachmentParameteriv, the red, green, blue and alpha sizes are queried from the GL_BACK_LEFT, while the depth and stencil sizes are queried from the GL_DEPTH and GL_STENCIL attachments, respectively.
GLFW_DOUBLEBUFFER indicates whether the specified window is double-buffered when rendering with OpenGL or OpenGL ES. This can be set before creation with the GLFW_DOUBLEBUFFER window hint.
GLFW windows are by default double buffered. That means that you have two rendering buffers; a front buffer and a back buffer. The front buffer is the one being displayed and the back buffer the one you render to.
When the entire frame has been rendered, it is time to swap the back and the front buffers in order to display what has been rendered and begin rendering a new frame. This is done with glfwSwapBuffers.
Sometimes it can be useful to select when the buffer swap will occur. With the function glfwSwapInterval it is possible to select the minimum number of monitor refreshes the driver should wait from the time glfwSwapBuffers was called before swapping the buffers:
If the interval is zero, the swap will take place immediately when glfwSwapBuffers is called without waiting for a refresh. Otherwise at least interval retraces will pass between each buffer swap. Using a swap interval of zero can be useful for benchmarking purposes, when it is not desirable to measure the time it takes to wait for the vertical retrace. However, a swap interval of one lets you avoid tearing.
Note that this may not work on all machines, as some drivers have user-controlled settings that override any swap interval the application requests.
A context that supports either the WGL_EXT_swap_control_tear or the GLX_EXT_swap_control_tear extension also accepts negative swap intervals, which allows the driver to swap immediately even if a frame arrives a little bit late. This trades the risk of visible tears for greater framerate stability. You can check for these extensions with glfwExtensionSupported.
Last update on Fri Feb 23 2024 for GLFW 3.4.0