docs/specs/EXT_shader_integer_mix.spec

   1 Name
   2
   3     EXT_shader_integer_mix
   4
   5 Name Strings
   6
   7     GL_EXT_shader_integer_mix
   8
   9 Contact
  10
  11     Matt Turner (matt.turner 'at' intel.com)
  12
  13 Contributors
  14
  15     Matt Turner, Intel
  16     Ian Romanick, Intel
  17
  18 Status
  19
  20     Shipping
  21
  22 Version
  23
  24     Last Modified Date:         09/12/2013
  25     Author Revision:            6
  26
  27 Number
  28
  29     TBD
  30
  31 Dependencies
  32
  33     OpenGL 3.0 or OpenGL ES 3.0 is required. This extension interacts with
  34     GL_ARB_ES3_compatibility.
  35
  36     This extension is written against the OpenGL 4.4 (core) specification
  37     and the GLSL 4.40 specification.
  38
  39 Overview
  40
  41     GLSL 1.30 (and GLSL ES 3.00) expanded the mix() built-in function to
  42     operate on a boolean third argument that does not interpolate but
  43     selects. This extension extends mix() to select between int, uint,
  44     and bool components.
  45
  46 New Procedures and Functions
  47
  48     None.
  49
  50 New Tokens
  51
  52     None.
  53
  54 Additions to Chapter 8 of the GLSL 4.40 Specification (Built-in Functions)
  55
  56     Modify Section 8.3, Common Functions
  57
  58     Additions to the table listing common built-in functions:
  59
  60       Syntax                       Description
  61       ---------------------------  --------------------------------------------------
  62       genIType mix(genIType x,     Selects which vector each returned component comes
  63                    genIType y,     from. For a component of a that is false, the
  64                    genBType a)     corresponding component of x is returned. For a
  65       genUType mix(genUType x,     component of a that is true, the corresponding
  66                    genUType y,     component of y is returned.
  67                    genBType a)
  68       genBType mix(genBType x,
  69                    genBType y,
  70                    genBType a)
  71
  72 Additions to the AGL/GLX/WGL Specifications
  73
  74     None.
  75
  76 Modifications to The OpenGL Shading Language Specification, Version 4.40
  77
  78     Including the following line in a shader can be used to control the
  79     language features described in this extension:
  80
  81       #extension GL_EXT_shader_integer_mix : <behavior>
  82
  83     where <behavior> is as specified in section 3.3.
  84
  85     New preprocessor #defines are added to the OpenGL Shading Language:
  86
  87       #define GL_EXT_shader_integer_mix        1
  88
  89 Interactions with ARB_ES3_compatibility
  90
  91     On desktop implementations that support ARB_ES3_compatibility,
  92     GL_EXT_shader_integer_mix can be enabled (and the new functions
  93     used) in shaders declared with '#version 300 es'.
  94
  95 GLX Protocol
  96
  97     None.
  98
  99 Errors
 100
 101     None.
 102
 103 New State
 104
 105     None.
 106
 107 New Implementation Dependent State
 108
 109     None.
 110
 111 Issues
 112
 113     1) Should we allow linear interpolation of integers via a non-boolean
 114        third component?
 115
 116     RESOLVED: No.
 117
 118     2) Should we allow mix() to select between boolean components?
 119
 120     RESOLVED: Yes. Implementing the same functionality using casts would be
 121     possible but ugly.
 122
 123 Revision History
 124
 125     Rev.    Date      Author    Changes
 126     ----  --------    --------  ---------------------------------------------
 127       6   09/12/2013  idr       After discussions in Khronos, change vendor
 128                                 prefix to EXT.
 129
 130       5   09/09/2013  idr       Add ARB_ES3_compatibility interaction.
 131
 132       4   09/06/2013  mattst88  Allow extension on OpenGL ES 3.0.
 133
 134       3   08/28/2013  mattst88  Add #extension/#define changes.
 135
 136       2   08/26/2013  mattst88  Change vendor prefix to MESA. Add mix() that
 137                                 selects between boolean components.
 138       1   08/26/2013  mattst88  Initial revision