| Name |
| |
| EXT_swap_control |
| |
| Name Strings |
| |
| WGL_EXT_swap_control |
| |
| Version |
| |
| Date: 9/23/1999 Revision: 1.5 |
| |
| Number |
| |
| 172 |
| |
| Dependencies |
| |
| WGL_EXT_extensions_string is required. |
| |
| Overview |
| |
| This extension allows an application to specify a minimum periodicity |
| of color buffer swaps, measured in video frame periods. |
| |
| New Procedures and Functions |
| |
| BOOL wglSwapIntervalEXT(int interval) |
| |
| int wglGetSwapIntervalEXT(void) |
| |
| New Tokens |
| |
| None |
| |
| Additions to Chapter 2 of the 1.2 GL Specification (OpenGL Operation) |
| |
| None |
| |
| Additions to Chapter 3 of the 1.2 GL Specification (Rasterization) |
| |
| None |
| |
| Additions to Chapter 4 of the 1.2 GL Specification (Per-Fragment Operations |
| and the Framebuffer) |
| |
| None |
| |
| Additions to Chapter 5 of the 1.2 GL Specification (Special Functions) |
| |
| None |
| |
| Additions to Chapter 6 of the 1.2 GL Specification (State and State Requests) |
| |
| None |
| |
| Additions to the WGL Specification |
| |
| wglSwapIntervalEXT specifies the minimum number of video frame periods |
| per buffer swap for the window associated with the current context. |
| The interval takes effect when SwapBuffers or wglSwapLayerBuffer |
| is first called subsequent to the wglSwapIntervalEXT call. |
| |
| The parameter <interval> specifies the minimum number of video frames |
| that are displayed before a buffer swap will occur. |
| |
| A video frame period is the time required by the monitor to display a |
| full frame of video data. In the case of an interlaced monitor, |
| this is typically the time required to display both the even and odd |
| fields of a frame of video data. An interval set to a value of 2 |
| means that the color buffers will be swapped at most every other video |
| frame. |
| |
| If <interval> is set to a value of 0, buffer swaps are not synchron- |
| ized to a video frame. The <interval> value is silently clamped to |
| the maximum implementation-dependent value supported before being |
| stored. |
| |
| The swap interval is not part of the render context state. It cannot |
| be pushed or popped. The current swap interval for the window |
| associated with the current context can be obtained by calling |
| wglGetSwapIntervalEXT. The default swap interval is 1. |
| |
| Dependencies on WGL_EXT_extensions_string |
| |
| Because there is no way to extend wgl, these calls are defined in |
| the ICD and can be called by obtaining the address with |
| wglGetProcAddress. Because this extension is a WGL extension, it |
| is not included in the GL_EXTENSIONS string. Its existence can be |
| determined with the WGL_EXT_extensions_string extension. |
| |
| For historical reasons, GL_EXT_SWAP_CONTROL is also included in the |
| GL_EXTENSIONS string as return from glGetString. |
| |
| Errors |
| |
| If the function succeeds, the return value is TRUE. If the function |
| fails, the return value is FALSE. To get extended error information, |
| call GetLastError. |
| |
| ERROR_INVALID_DATA The <interval> parameter is negative. |
| |
| ERROR_DC_NOT_FOUND An RC was not current to the calling |
| thread; therefore, no DC could be |
| obtained. |
| |
| New State |
| |
| None |
| |
| New Implementation Dependent State |
| |
| None |