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1Name
2
3    INGR_interlace_read
4
5Name Strings
6
7    GL_INGR_interlace_read
8
9Version
10
11    Date: 12/14/98    Revision: 1.0
12
13Number
14
15    175
16
17Dependencies
18
19    None
20
21Overview
22
23    This extension provides a way to skip rows of pixels when reading
24    or copying pixel rectangles.  This extension is complementary to
25    the EXT_interlace extension except that it has no affect on getting
26    texture images.
27
28New Procedures and Functions
29
30    None
31
32New Tokens
33
34    Accepted by the <cap> parameter of of Enable, Disable, IsEnabled, and
35    by the <pname> parameter of GetBooleanv, GetIntegerv, GetFloatv,
36    GetDoublev:
37
38      INTERLACE_READ_INGR                   0x8568
39
40Additions to Chapter 2 of the 1.2 Specification (OpenGL Operation)
41
42    None
43
44Additions to Chapter 3 of the 1.2 Specification (Rasterization)
45
46    None
47
48Additions to Chapter 4 of the 1.2 Specification (Per-Fragment Operations
49and the Frame Buffer)
50
51    [In section 4.3.2 "Reading Pixels" the specification of an interlace
52    read operation is added to the GL Specification in the sectino on
53    "Obtaining Pixels from the FrameBuffer."]
54
55    Reading interlaced rows of pixels is enabled or disabled with Enable
56    or Disable using the symbolic constant INTERLACE_READ_INGR.  If
57    INTERLACE_READ_INGR is disabled, then ReadPixels obtains values from
58    the selected buffer from each pixel with lower left hand corner at
59    (x+i, y+j) for 0 <= i < width and 0 <= j < height; this pixel is said
60    to be the ith pixel in the jth row.
61
62    If INTERLACE_READ_INGR is enabled, then ReadPixels obtains values
63    from the selected buffer from each pixel with lower left hand corner
64    at (x+i, y+(j*2)) for 0 <= i < width and 0 <= j < height; this pixel
65    is said to be the ith pixel in the jth row.
66
67    If any of these pixels lies outside of the window...
68
69Additions to Chapter 5 of the 1.2 Specification (Special Functions)
70
71    None
72
73Additions to Chapter 6 of the 1.2 Specification (State and State Requests)
74
75    None
76
77Additions to the GLX Specification
78
79    None
80
81Errors
82
83    None
84
85New State
86
87    Get Value              Get Command        Type    Initial Value    Attribute
88    --------------------   ---------------    -----   --------------   -------------
89    INTERLACE_READ_INGR     IsEnabled          B       False            pixel/enable
90
91New Implementation Dependent State
92
93    None
94