docs/MESA_swap_control.spec

   1 Name
   2
   3     MESA_swap_control
   4
   5 Name Strings
   6
   7     GLX_MESA_swap_control
   8
   9 Contact
  10
  11     Ian Romanick, IBM, idr at us.ibm.com
  12
  13 Status
  14
  15     Deployed in DRI drivers post-XFree86 4.3.
  16
  17 Version
  18
  19     Date: 5/1/2003   Revision: 1.1
  20
  21 Number
  22
  23     ???
  24
  25 Dependencies
  26
  27     None
  28
  29     Based on GLX_SGI_swap_control version 1.9 and WGL_EXT_swap_control
  30     version 1.5.
  31
  32 Overview
  33
  34     This extension allows an application to specify a minimum periodicity
  35     of color buffer swaps, measured in video frame periods.
  36
  37 Issues
  38
  39     * Should implementations that export GLX_MESA_swap_control also export
  40       GL_EXT_swap_control for compatibility with WGL_EXT_swap_control?
  41
  42     UNRESOLVED.
  43
  44 New Procedures and Functions
  45
  46     int glXSwapIntervalMESA(int interval)
  47     int glXGetSwapIntervalMESA(void)
  48
  49 New Tokens
  50
  51     None
  52
  53 Additions to Chapter 2 of the 1.4 GL Specification (OpenGL Operation)
  54
  55     None
  56
  57 Additions to Chapter 3 of the 1.4 GL Specification (Rasterization)
  58
  59     None
  60
  61 Additions to Chapter 4 of the 1.4 GL Specification (Per-Fragment Operations
  62 and the Framebuffer)
  63
  64     None
  65
  66 Additions to Chapter 5 of the 1.4 GL Specification (Special Functions)
  67
  68     None
  69
  70 Additions to Chapter 6 of the 1.4 GL Specification (State and State Requests)
  71
  72     None
  73
  74 Additions to the GLX 1.3 Specification
  75
  76     [Add the following to Section 3.3.10 of the GLX Specification (Double
  77      Buffering)]
  78
  79     glXSwapIntervalMESA specifies the minimum number of video frame periods
  80     per buffer swap.  (e.g. a value of two means that the color buffers
  81     will be swapped at most every other video frame.)  A return value
  82     of zero indicates success; otherwise an error occurred.  The interval
  83     takes effect when glXSwapBuffers is first called subsequent to the
  84     glXSwapIntervalMESA call.
  85
  86     A video frame period is the time required by the monitor to display a
  87     full frame of video data.  In the case of an interlaced monitor,
  88     this is typically the time required to display both the even and odd
  89     fields of a frame of video data.
  90
  91     If <interval> is set to a value of 0, buffer swaps are not synchron-
  92     ized to a video frame.  The <interval> value is silently clamped to
  93     the maximum implementation-dependent value supported before being
  94     stored.
  95
  96     The swap interval is not part of the render context state.  It cannot
  97     be pushed or popped.  The current swap interval for the window
  98     associated with the current context can be obtained by calling
  99     glXGetSwapIntervalMESA.  The default swap interval is 0.
 100
 101     On XFree86, setting the environment variable LIBGL_THROTTLE_REFRESH sets
 102     the swap interval to 1.
 103
 104 Errors
 105
 106     glXSwapIntervalMESA returns GLX_BAD_VALUE if parameter <interval> is
 107     less than zero.
 108
 109     glXSwapIntervalMESA returns GLX_BAD_CONTEXT if there is no current
 110     GLXContext.
 111
 112 GLX Protocol
 113
 114     None.  This extension only extends to direct rendering contexts.
 115
 116 New State
 117
 118     Get Value           Get Command     Type        Initial Value
 119     ---------           -----------     ----        -------------
 120     [swap interval]     GetSwapInterval Z+          0
 121
 122 New Implementation Dependent State
 123
 124     None
 125
 126
 127 Revision History
 128
 129     1.1,  5/1/03   Added the issues section and contact information.
 130                    Changed the default swap interval to 0.
 131     1.0,  3/17/03  Initial version based on GLX_SGI_swap_control and
 132                    WGL_EXT_swap_control.