269 lines
8.4 KiB
Plaintext
269 lines
8.4 KiB
Plaintext
/*!
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@page monitor_guide Monitor guide
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@tableofcontents
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This guide introduces the monitor related functions of GLFW. For details on
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a specific function in this category, see the @ref monitor. There are also
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guides for the other areas of GLFW.
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- @ref intro_guide
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- @ref window_guide
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- @ref context_guide
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- @ref vulkan_guide
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- @ref input_guide
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@section monitor_object Monitor objects
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A monitor object represents a currently connected monitor and is represented as
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a pointer to the [opaque](https://en.wikipedia.org/wiki/Opaque_data_type) type
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@ref GLFWmonitor. Monitor objects cannot be created or destroyed by the
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application and retain their addresses until the monitors they represent are
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disconnected or until the library is [terminated](@ref intro_init_terminate).
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Each monitor has a current video mode, a list of supported video modes,
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a virtual position, a human-readable name, an estimated physical size and
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a gamma ramp. One of the monitors is the primary monitor.
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The virtual position of a monitor is in
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[screen coordinates](@ref coordinate_systems) and, together with the current
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video mode, describes the viewports that the connected monitors provide into the
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virtual desktop that spans them.
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To see how GLFW views your monitor setup and its available video modes, run the
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`monitors` test program.
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@subsection monitor_monitors Retrieving monitors
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The primary monitor is returned by @ref glfwGetPrimaryMonitor. It is the user's
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preferred monitor and is usually the one with global UI elements like task bar
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or menu bar.
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@code
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GLFWmonitor* primary = glfwGetPrimaryMonitor();
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@endcode
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You can retrieve all currently connected monitors with @ref glfwGetMonitors.
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See the reference documentation for the lifetime of the returned array.
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@code
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int count;
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GLFWmonitor** monitors = glfwGetMonitors(&count);
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@endcode
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The primary monitor is always the first monitor in the returned array, but other
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monitors may be moved to a different index when a monitor is connected or
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disconnected.
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@subsection monitor_event Monitor configuration changes
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If you wish to be notified when a monitor is connected or disconnected, set
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a monitor callback.
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@code
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glfwSetMonitorCallback(monitor_callback);
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@endcode
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The callback function receives the handle for the monitor that has been
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connected or disconnected and the event that occurred.
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@code
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void monitor_callback(GLFWmonitor* monitor, int event)
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{
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if (event == GLFW_CONNECTED)
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{
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// The monitor was connected
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}
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else if (event == GLFW_DISCONNECTED)
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{
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// The monitor was disconnected
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}
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}
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@endcode
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If a monitor is disconnected, all windows that are full screen on it will be
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switched to windowed mode before the callback is called. Only @ref
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glfwGetMonitorName and @ref glfwGetMonitorUserPointer will return useful values
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for a disconnected monitor and only before the monitor callback returns.
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@section monitor_properties Monitor properties
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Each monitor has a current video mode, a list of supported video modes,
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a virtual position, a content scale, a human-readable name, a user pointer, an
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estimated physical size and a gamma ramp.
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@subsection monitor_modes Video modes
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GLFW generally does a good job selecting a suitable video mode when you create
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a full screen window, change its video mode or make a windowed one full
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screen, but it is sometimes useful to know exactly which video modes are
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supported.
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Video modes are represented as @ref GLFWvidmode structures. You can get an
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array of the video modes supported by a monitor with @ref glfwGetVideoModes.
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See the reference documentation for the lifetime of the returned array.
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@code
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int count;
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GLFWvidmode* modes = glfwGetVideoModes(monitor, &count);
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@endcode
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To get the current video mode of a monitor call @ref glfwGetVideoMode. See the
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reference documentation for the lifetime of the returned pointer.
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@code
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const GLFWvidmode* mode = glfwGetVideoMode(monitor);
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@endcode
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The resolution of a video mode is specified in
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[screen coordinates](@ref coordinate_systems), not pixels.
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@subsection monitor_size Physical size
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The physical size of a monitor in millimetres, or an estimation of it, can be
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retrieved with @ref glfwGetMonitorPhysicalSize. This has no relation to its
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current _resolution_, i.e. the width and height of its current
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[video mode](@ref monitor_modes).
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@code
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int width_mm, height_mm;
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glfwGetMonitorPhysicalSize(monitor, &width_mm, &height_mm);
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@endcode
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While this can be used to calculate the raw DPI of a monitor, this is often not
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useful. Instead use the [monitor content scale](@ref monitor_scale) and
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[window content scale](@ref window_scale) to scale your content.
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@subsection monitor_scale Content scale
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The content scale for a monitor can be retrieved with @ref
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glfwGetMonitorContentScale.
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@code
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float xscale, yscale;
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glfwGetMonitorContentScale(monitor, &xscale, &yscale);
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@endcode
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The content scale is the ratio between the current DPI and the platform's
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default DPI. This is especially important for text and any UI elements. If the
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pixel dimensions of your UI scaled by this look appropriate on your machine then
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it should appear at a reasonable size on other machines regardless of their DPI
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and scaling settings. This relies on the system DPI and scaling settings being
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somewhat correct.
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The content scale may depend on both the monitor resolution and pixel density
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and on user settings. It may be very different from the raw DPI calculated from
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the physical size and current resolution.
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@subsection monitor_pos Virtual position
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The position of the monitor on the virtual desktop, in
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[screen coordinates](@ref coordinate_systems), can be retrieved with @ref
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glfwGetMonitorPos.
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@code
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int xpos, ypos;
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glfwGetMonitorPos(monitor, &xpos, &ypos);
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@endcode
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@subsection monitor_workarea Work area
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The area of a monitor not occupied by global task bars or menu bars is the work
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area. This is specified in [screen coordinates](@ref coordinate_systems) and
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can be retrieved with @ref glfwGetMonitorWorkarea.
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@code
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int xpos, ypos, width, height;
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glfwGetMonitorWorkarea(monitor, &xpos, &ypos, &width, &height);
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@endcode
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@subsection monitor_name Human-readable name
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The human-readable, UTF-8 encoded name of a monitor is returned by @ref
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glfwGetMonitorName. See the reference documentation for the lifetime of the
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returned string.
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@code
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const char* name = glfwGetMonitorName(monitor);
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@endcode
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Monitor names are not guaranteed to be unique. Two monitors of the same model
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and make may have the same name. Only the monitor handle is guaranteed to be
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unique, and only until that monitor is disconnected.
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@subsection monitor_userptr User pointer
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Each monitor has a user pointer that can be set with @ref
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glfwSetMonitorUserPointer and queried with @ref glfwGetMonitorUserPointer. This
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can be used for any purpose you need and will not be modified by GLFW. The
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value will be kept until the monitor is disconnected or until the library is
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terminated.
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The initial value of the pointer is `NULL`.
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@subsection monitor_gamma Gamma ramp
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The gamma ramp of a monitor can be set with @ref glfwSetGammaRamp, which accepts
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a monitor handle and a pointer to a @ref GLFWgammaramp structure.
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@code
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GLFWgammaramp ramp;
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unsigned short red[256], green[256], blue[256];
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ramp.size = 256;
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ramp.red = red;
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ramp.green = green;
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ramp.blue = blue;
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for (i = 0; i < ramp.size; i++)
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{
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// Fill out gamma ramp arrays as desired
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}
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glfwSetGammaRamp(monitor, &ramp);
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@endcode
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The gamma ramp data is copied before the function returns, so there is no need
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to keep it around once the ramp has been set.
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It is recommended that your gamma ramp have the same size as the current gamma
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ramp for that monitor.
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The current gamma ramp for a monitor is returned by @ref glfwGetGammaRamp. See
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the reference documentation for the lifetime of the returned structure.
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@code
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const GLFWgammaramp* ramp = glfwGetGammaRamp(monitor);
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@endcode
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If you wish to set a regular gamma ramp, you can have GLFW calculate it for you
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from the desired exponent with @ref glfwSetGamma, which in turn calls @ref
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glfwSetGammaRamp with the resulting ramp.
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@code
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glfwSetGamma(monitor, 1.0);
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@endcode
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To experiment with gamma correction via the @ref glfwSetGamma function, run the
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`gamma` test program.
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@note The software controlled gamma ramp is applied _in addition_ to the
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hardware gamma correction, which today is usually an approximation of sRGB
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gamma. This means that setting a perfectly linear ramp, or gamma 1.0, will
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produce the default (usually sRGB-like) behavior.
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*/
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