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Name
INGR_interlace_read
Name Strings
GL_INGR_interlace_read
Version
Date: 12/14/98 Revision: 1.0
Number
175
Dependencies
None
Overview
This extension provides a way to skip rows of pixels when reading
or copying pixel rectangles. This extension is complementary to
the EXT_interlace extension except that it has no affect on getting
texture images.
New Procedures and Functions
None
New Tokens
Accepted by the <cap> parameter of of Enable, Disable, IsEnabled, and
by the <pname> parameter of GetBooleanv, GetIntegerv, GetFloatv,
GetDoublev:
INTERLACE_READ_INGR 0x8568
Additions to Chapter 2 of the 1.2 Specification (OpenGL Operation)
None
Additions to Chapter 3 of the 1.2 Specification (Rasterization)
None
Additions to Chapter 4 of the 1.2 Specification (Per-Fragment Operations
and the Frame Buffer)
[In section 4.3.2 "Reading Pixels" the specification of an interlace
read operation is added to the GL Specification in the sectino on
"Obtaining Pixels from the FrameBuffer."]
Reading interlaced rows of pixels is enabled or disabled with Enable
or Disable using the symbolic constant INTERLACE_READ_INGR. If
INTERLACE_READ_INGR is disabled, then ReadPixels obtains values from
the selected buffer from each pixel with lower left hand corner at
(x+i, y+j) for 0 <= i < width and 0 <= j < height; this pixel is said
to be the ith pixel in the jth row.
If INTERLACE_READ_INGR is enabled, then ReadPixels obtains values
from the selected buffer from each pixel with lower left hand corner
at (x+i, y+(j*2)) for 0 <= i < width and 0 <= j < height; this pixel
is said to be the ith pixel in the jth row.
If any of these pixels lies outside of the window...
Additions to Chapter 5 of the 1.2 Specification (Special Functions)
None
Additions to Chapter 6 of the 1.2 Specification (State and State Requests)
None
Additions to the GLX Specification
None
Errors
None
New State
Get Value Get Command Type Initial Value Attribute
-------------------- --------------- ----- -------------- -------------
INTERLACE_READ_INGR IsEnabled B False pixel/enable
New Implementation Dependent State
None