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496 lines
19 KiB
496 lines
19 KiB
/*! |
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@page window Window handling guide |
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@tableofcontents |
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The primary purpose of GLFW is to provide a simple interface to window |
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management and OpenGL and OpenGL ES context creation. GLFW supports multiple |
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windows, which can be either a normal desktop window or a full screen window. |
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@section window_object Window handles |
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The @ref GLFWwindow object encapsulates both a window and a context. They are |
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created with @ref glfwCreateWindow and destroyed with @ref glfwDestroyWindow (or |
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@ref glfwTerminate, if any remain). As the window and context are inseparably |
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linked, the object pointer is used as both a context and window handle. |
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@section window_creation Window creation |
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The window and its context are created with @ref glfwCreateWindow, which |
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returns a handle to the created window object. For example, this creates a 640 |
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by 480 windowed mode window: |
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@code |
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GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", NULL, NULL); |
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@endcode |
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If window creation fails, `NULL` will be returned, so you need to check whether |
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it did. |
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This handle is then passed to all window related functions, and is provided to |
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you along with input events, so you know which window received the input. |
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To create a full screen window, you need to specify which monitor the window |
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should use. In most cases, the user's primary monitor is a good choice. For |
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more information about monitors, see the @ref monitor. |
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@code |
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GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", glfwGetPrimaryMonitor(), NULL); |
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@endcode |
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Full screen windows cover the entire display area of a monitor, have no border |
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or decorations, and change the monitor's resolution to the one most closely |
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matching the requested window size. |
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For more control over how the window and its context are created, see @ref |
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window_hints below. |
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@section window_destruction Window destruction |
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When you are done with the window, destroy it with the @ref glfwDestroyWindow |
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function. |
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@code |
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glfwDestroyWindow(window); |
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@endcode |
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Once this function is called, no more events will be delivered for that window |
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and its handle becomes invalid. |
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@section window_userptr Window user pointer |
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Each window has a user pointer that can be set with @ref |
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glfwSetWindowUserPointer and fetched with @ref glfwGetWindowUserPointer. This |
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can be used for any purpose you need and will not modified by GLFW throughout |
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the life-time of the window. |
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@section window_hints Window creation hints |
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There are a number of hints that can be set before the creation of a window and |
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context. Some affect the window itself, others affect the framebuffer or |
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context. These hints are set to their default values each time the library is |
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initialized with @ref glfwInit, can be set individually with @ref glfwWindowHint |
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and reset all at once to their defaults with @ref glfwDefaultWindowHints. |
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Note that hints need to be set *before* the creation of the window and context |
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you wish to have the specified attributes. |
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@subsection window_hints_hard Hard and soft constraints |
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Some window hints are hard constraints. These must match the available |
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capabilities *exactly* for window and context creation to succeed. Hints |
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that are not hard constraints are matched as closely as possible, but the |
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resulting window and context may differ from what these hints requested. To |
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find out the actual attributes of the created window and context, use the |
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@ref glfwGetWindowAttrib function. |
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The following hints are hard constraints: |
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- `GLFW_STEREO` |
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- `GLFW_CLIENT_API` |
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The following additional hints are hard constraints if requesting an OpenGL |
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context: |
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- `GLFW_OPENGL_FORWARD_COMPAT` |
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- `GLFW_OPENGL_PROFILE` |
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Hints that do not apply to a given type of window or context are ignored. |
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@subsection window_hints_wnd Window related hints |
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The `GLFW_RESIZABLE` hint specifies whether the window will be resizable *by the |
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user*. The window will still be resizable using the @ref glfwSetWindowSize |
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function. This hint is ignored for full screen windows. |
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The `GLFW_VISIBLE` hint specifies whether the window will be initially |
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visible. This hint is ignored for full screen windows. |
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The `GLFW_DECORATED` hint specifies whether the window will have window |
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decorations such as a border, a close widget, etc. This hint is ignored for |
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full screen windows. Note that even though a window may lack a close widget, it |
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is usually still possible for the user to generate close events. |
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@subsection window_hints_fb Framebuffer related hints |
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The `GLFW_RED_BITS`, `GLFW_GREEN_BITS`, `GLFW_BLUE_BITS`, `GLFW_ALPHA_BITS`, |
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`GLFW_DEPTH_BITS` and `GLFW_STENCIL_BITS` hints specify the desired bit |
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depths of the various components of the default framebuffer. |
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The `GLFW_ACCUM_RED_BITS`, `GLFW_ACCUM_GREEN_BITS`, `GLFW_ACCUM_BLUE_BITS` |
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and `GLFW_ACCUM_ALPHA_BITS` hints specify the desired bit depths of the |
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various components of the accumulation buffer. |
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The `GLFW_AUX_BUFFERS` hint specifies the desired number of auxiliary |
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buffers. |
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The `GLFW_STEREO` hint specifies whether to use stereoscopic rendering. |
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The `GLFW_SAMPLES` hint specifies the desired number of samples to use for |
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multisampling. Zero disables multisampling. |
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The `GLFW_SRGB_CAPABLE` hint specifies whether the framebuffer should be |
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sRGB capable. |
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The `GLFW_REFRESH_RATE` hint specifies the desired refresh rate for full screen |
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windows. If set to zero, the highest available refresh rate will be used. This |
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hint is ignored for windowed mode windows. |
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@subsection window_hints_ctx Context related hints |
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The `GLFW_CLIENT_API` hint specifies which client API to create the context |
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for. Possible values are `GLFW_OPENGL_API` and `GLFW_OPENGL_ES_API`. |
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The `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR` hints |
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specify the client API version that the created context must be compatible |
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with. |
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For OpenGL, these hints are *not* hard constraints, as they don't have to |
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match exactly, but @ref glfwCreateWindow will still fail if the resulting |
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OpenGL version is less than the one requested. It is therefore perfectly |
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safe to use the default of version 1.0 for legacy code and you may still |
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get backwards-compatible contexts of version 3.0 and above when available. |
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While there is no way to ask the driver for a context of the highest supported |
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version, most drivers provide this when you ask GLFW for a version |
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1.0 context. |
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For OpenGL ES, these hints are hard constraints. |
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If an OpenGL context is requested, the `GLFW_OPENGL_FORWARD_COMPAT` hint |
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specifies whether the OpenGL context should be forward-compatible, i.e. one |
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where all functionality deprecated in the requested version of OpenGL is |
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removed. This may only be used if the requested OpenGL version is 3.0 or |
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above. If another client API is requested, this hint is ignored. |
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If an OpenGL context is requested, the `GLFW_OPENGL_DEBUG_CONTEXT` hint |
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specifies whether to create a debug OpenGL context, which may have |
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additional error and performance issue reporting functionality. If another |
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client API is requested, this hint is ignored. |
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If an OpenGL context is requested, the `GLFW_OPENGL_PROFILE` hint specifies |
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which OpenGL profile to create the context for. Possible values are one of |
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`GLFW_OPENGL_CORE_PROFILE` or `GLFW_OPENGL_COMPAT_PROFILE`, or |
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`GLFW_OPENGL_ANY_PROFILE` to not request a specific profile. If requesting |
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an OpenGL version below 3.2, `GLFW_OPENGL_ANY_PROFILE` must be used. If |
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another client API is requested, this hint is ignored. |
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The `GLFW_CONTEXT_ROBUSTNESS` hint specifies the robustness strategy to be |
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used by the context. This can be one of `GLFW_NO_RESET_NOTIFICATION` or |
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`GLFW_LOSE_CONTEXT_ON_RESET`, or `GLFW_NO_ROBUSTNESS` to not request |
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a robustness strategy. |
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@subsection window_hints_values Supported and default values |
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| Name | Default value | Supported values | |
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| ---------------------------- | ------------------------- | ----------------------- | |
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| `GLFW_RESIZABLE` | `GL_TRUE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_VISIBLE` | `GL_TRUE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_DECORATED` | `GL_TRUE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_RED_BITS` | 8 | 0 to `INT_MAX` | |
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| `GLFW_GREEN_BITS` | 8 | 0 to `INT_MAX` | |
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| `GLFW_BLUE_BITS` | 8 | 0 to `INT_MAX` | |
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| `GLFW_ALPHA_BITS` | 8 | 0 to `INT_MAX` | |
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| `GLFW_DEPTH_BITS` | 24 | 0 to `INT_MAX` | |
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| `GLFW_STENCIL_BITS` | 8 | 0 to `INT_MAX` | |
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| `GLFW_ACCUM_RED_BITS` | 0 | 0 to `INT_MAX` | |
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| `GLFW_ACCUM_GREEN_BITS` | 0 | 0 to `INT_MAX` | |
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| `GLFW_ACCUM_BLUE_BITS` | 0 | 0 to `INT_MAX` | |
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| `GLFW_ACCUM_ALPHA_BITS` | 0 | 0 to `INT_MAX` | |
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| `GLFW_AUX_BUFFERS` | 0 | 0 to `INT_MAX` | |
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| `GLFW_SAMPLES` | 0 | 0 to `INT_MAX` | |
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| `GLFW_REFRESH_RATE` | 0 | 0 to `INT_MAX` | |
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| `GLFW_STEREO` | `GL_FALSE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_SRGB_CAPABLE` | `GL_FALSE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_CLIENT_API` | `GLFW_OPENGL_API` | `GLFW_OPENGL_API` or `GLFW_OPENGL_ES_API` | |
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| `GLFW_CONTEXT_VERSION_MAJOR` | 1 | Any valid major version number of the chosen client API | |
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| `GLFW_CONTEXT_VERSION_MINOR` | 0 | Any valid minor version number of the chosen client API | |
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| `GLFW_CONTEXT_ROBUSTNESS` | `GLFW_NO_ROBUSTNESS` | `GLFW_NO_ROBUSTNESS`, `GLFW_NO_RESET_NOTIFICATION` or `GLFW_LOSE_CONTEXT_ON_RESET` | |
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| `GLFW_OPENGL_FORWARD_COMPAT` | `GL_FALSE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_OPENGL_DEBUG_CONTEXT` | `GL_FALSE` | `GL_TRUE` or `GL_FALSE` | |
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| `GLFW_OPENGL_PROFILE` | `GLFW_OPENGL_ANY_PROFILE` | `GLFW_OPENGL_ANY_PROFILE`, `GLFW_OPENGL_COMPAT_PROFILE` or `GLFW_OPENGL_CORE_PROFILE` | |
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@section window_close Window close flag |
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When the user attempts to close the window, for example by clicking the close |
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widget or using a key chord like Alt+F4, the *close flag* of the window is set. |
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The window is however not actually destroyed and, unless you watch for this |
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state change, nothing further happens. |
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The current state of the close flag is returned by @ref glfwWindowShouldClose |
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and can be set or cleared directly with @ref glfwSetWindowShouldClose. A common |
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pattern is to use the close flag as a main loop condition. |
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@code |
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while (!glfwWindowShouldClose(window)) |
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{ |
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render(window); |
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glfwSwapBuffers(window); |
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glfwPollEvents(); |
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} |
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@endcode |
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If you wish to be notified when the user attempts to close a window, you can set |
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the close callback with @ref glfwSetWindowCloseCallback. This callback is |
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called directly *after* the close flag has been set. |
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@code |
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glfwSetWindowCloseCallback(window, window_close_callback); |
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@endcode |
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The callback function can be used for example to filter close requests and clear |
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the close flag again unless certain conditions are met. |
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@code |
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void window_close_callback(GLFWwindow* window) |
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{ |
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if (!time_to_close) |
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glfwSetWindowShouldClose(window, GL_FALSE); |
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} |
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@endcode |
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@section window_size Window size |
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The size of a window can be changed with @ref glfwSetWindowSize. For windowed |
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mode windows, this resizes the specified window so that its *client area* has |
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the specified size. Note that the window system may put limitations on size. |
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For full screen windows, it selects and sets the video mode most closely |
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matching the specified size. |
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@code |
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void glfwSetWindowSize(window, 640, 480); |
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@endcode |
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If you wish to be notified when a window is resized, whether by the user or |
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the system, you can set the size callback with @ref glfwSetWindowSizeCallback. |
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@code |
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glfwSetWindowSizeCallback(window, window_size_callback); |
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@endcode |
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The callback function receives the new size of the client area of the window. |
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@code |
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void window_size_callback(GLFWwindow* window, int width, int height) |
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{ |
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} |
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@endcode |
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There is also @ref glfwGetWindowSize for directly retrieving the current size of |
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a window. |
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@code |
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int width, height; |
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glfwGetWindowSize(window, &width, &height); |
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@endcode |
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@section window_fbsize Window framebuffer size |
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While the size of a window is measured in screen coordinates, OpenGL works with |
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pixels. The size you pass into `glViewport`, for example, should be in pixels |
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and not screen coordinates. On some platforms screen coordinates and pixels are |
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the same, but this is not the case on all platforms supported by GLFW. There is |
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a second set of functions to retrieve the size in pixels of the framebuffer of |
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a window. |
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If you wish to be notified when the framebuffer of a window is resized, whether |
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by the user or the system, you can set the size callback with @ref |
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glfwSetFramebufferSizeCallback. |
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@code |
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glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); |
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@endcode |
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The callback function receives the new size of the client area of the window, |
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which can for example be used to update the OpenGL viewport. |
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@code |
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void framebuffer_size_callback(GLFWwindow* window, int width, int height) |
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{ |
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glViewport(0, 0, width, height); |
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} |
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@endcode |
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There is also @ref glfwGetFramebufferSize for directly retrieving the current |
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size of the framebuffer of a window. |
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@code |
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int width, height; |
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glfwGetFramebufferSize(window, &width, &height); |
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glViewport(0, 0, width, height); |
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@endcode |
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Note that the size of a framebuffer may change independently of the size of |
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a window, for example if the window is dragged between a regular monitor and |
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a high-DPI one. |
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@section window_pos Window position |
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The position of a windowed-mode window can be changed with @ref |
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glfwSetWindowPos. This moves the window so that the upper-left corner of its |
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client area has the specified screen coordinates. Note that the window system |
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may put limitations on placement. |
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@code |
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glfwSetWindowPos(window, 100, 100); |
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@endcode |
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If you wish to be notified when a window is moved, whether by the user or |
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the system, you can set the position callback with @ref glfwSetWindowPosCallback. |
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@code |
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glfwSetWindowPosCallback(window, window_pos_callback); |
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@endcode |
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The callback function receives the new position of the upper-left corner of its |
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client area. |
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@code |
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void window_size_callback(GLFWwindow* window, int xpos, int ypos) |
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{ |
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} |
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@endcode |
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There is also @ref glfwGetWindowPos for directly retrieving the current position |
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of the client area of the window. |
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@code |
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int xpos, ypos; |
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glfwGetWindowPos(window, &xpos, &ypos); |
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@endcode |
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@section window_title Window title |
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All GLFW windows have a title, although undecorated or full screen windows may |
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not display it or only display it in a task bar or similar interface. To change |
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the title of a window, use @ref glfwSetWindowTitle. |
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@code |
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glfwSetWindowTitle(window, "My Window"); |
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@endcode |
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The window title is a regular C string using the UTF-8 encoding. This means |
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for example that, as long as your source file is encoded as UTF-8, you can use |
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any Unicode characters. |
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@code |
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glfwSetWindowTitle(window, "さよなら絶望先生"); |
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@endcode |
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@section window_attribs Window attributes |
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Windows have a number of attributes that can be returned using @ref |
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glfwGetWindowAttrib. Some reflect state that may change during the lifetime of |
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the window, while others reflect the corresponding hints and are fixed at the |
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time of creation. |
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@code |
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if (glfwGetWindowAttrib(window, GLFW_FOCUSED)) |
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{ |
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// window has input focus |
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} |
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@endcode |
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@subsection window_attribs_window Window attributes |
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The `GLFW_FOCUSED` attribute indicates whether the specified window currently |
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has input focus. |
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The `GLFW_ICONIFIED` attribute indicates whether the specified window is |
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currently iconified, whether by the user or with @ref glfwIconifyWindow. |
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The `GLFW_VISIBLE` attribute indicates whether the specified window is currently |
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visible. Window visibility can be controlled with @ref glfwShowWindow and @ref |
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glfwHideWindow and initial visibility is controlled by the |
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[window hint](@ref window_hints) with the same name. |
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The `GLFW_RESIZABLE` attribute indicates whether the specified window is |
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resizable *by the user*. This is controlled by the |
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[window hint](@ref window_hints) with the same name. |
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The `GLFW_DECORATED` attribute indicates whether the specified window has |
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decorations such as a border, a close widget, etc. This is controlled by the |
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[window hint](@ref window_hints) with the same name. |
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@subsection window_attribs_context Context attributes |
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The `GLFW_CLIENT_API` attribute indicates the client API provided by the |
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window's context; either `GLFW_OPENGL_API` or `GLFW_OPENGL_ES_API`. |
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The `GLFW_CONTEXT_VERSION_MAJOR`, `GLFW_CONTEXT_VERSION_MINOR` and |
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`GLFW_CONTEXT_REVISION` attributes indicate the client API version of the |
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window's context. |
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The `GLFW_OPENGL_FORWARD_COMPAT` attribute is `GL_TRUE` if the window's |
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context is an OpenGL forward-compatible one, or `GL_FALSE` otherwise. |
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The `GLFW_OPENGL_DEBUG_CONTEXT` attribute is `GL_TRUE` if the window's |
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context is an OpenGL debug context, or `GL_FALSE` otherwise. |
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The `GLFW_OPENGL_PROFILE` attribute indicates the OpenGL profile used by the |
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context. This is `GLFW_OPENGL_CORE_PROFILE` or `GLFW_OPENGL_COMPAT_PROFILE` |
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if the context uses a known profile, or `GLFW_OPENGL_ANY_PROFILE` if the |
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OpenGL profile is unknown or the context is for another client API. Note that |
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the returned profile may not match the profile bits of the context flags, as |
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GLFW will try other means of detecting the profile when no bits are set. |
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The `GLFW_CONTEXT_ROBUSTNESS` attribute indicates the robustness strategy |
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used by the context. This is `GLFW_LOSE_CONTEXT_ON_RESET` or |
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`GLFW_NO_RESET_NOTIFICATION` if the window's context supports robustness, or |
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`GLFW_NO_ROBUSTNESS` otherwise. |
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@section window_swap Swapping buffers |
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GLFW windows are always double buffered. That means that you have two |
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rendering buffers; a front buffer and a back buffer. The front buffer is |
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the one being displayed and the back buffer the one you render to. |
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When the entire frame has been rendered, it is time to swap the back and the |
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front buffers in order to display what has been rendered and begin rendering |
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a new frame. This is done with @ref glfwSwapBuffers. |
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@code |
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glfwSwapBuffers(window); |
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@endcode |
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Sometimes it can be useful to select when the buffer swap will occur. With the |
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function @ref glfwSwapInterval it is possible to select the minimum number of |
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monitor refreshes the driver should wait before swapping the buffers: |
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@code |
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glfwSwapInterval(1); |
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@endcode |
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If the interval is zero, the swap will take place immediately when @ref |
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glfwSwapBuffers is called without waiting for a refresh. Otherwise at least |
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interval retraces will pass between each buffer swap. Using a swap interval of |
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zero can be useful for benchmarking purposes, when it is not desirable to |
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measure the time it takes to wait for the vertical retrace. However, a swap |
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interval of one lets you avoid tearing. |
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Note that this may not work on all machines, as some drivers have |
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user-controlled settings that override any swap interval the application |
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requests. It is also by default disabled on Windows Vista and later when using |
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DWM (Aero), as using it there sometimes leads to severe jitter. You can |
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forcibly enable it for machines using DWM using @ref compile_options_win32. |
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*/
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