glPixelStorei
- set pixel storage modes
void glPixelStorei(GLenum pname, GLint param)
pname
Specifies the symbolic name of the parameter to be set. GL_PACK_ALIGNMENT
affects the packing of pixel data into memory. GL_UNPACK_ALIGNMENT
affects the unpacking of pixel data from
memory.
param
Specifies the value that pname
is set to.
glPixelStore
sets pixel storage modes that affect the operation of subsequent glReadPixels
as well as the unpacking of glTexImage2D
, and glTexSubImage2D
.
pname
is a symbolic constant indicating the parameter to be set, and param
is the new value. The following storage parameter affects how pixel data is returned to client memory. This value is significant for glReadPixels
:
GL_PACK_ALIGNMENT
Specifies the alignment requirements for the start of each pixel row in memory. The allowable values are 1 (byte-alignment), 2 (rows aligned to even-numbered bytes), 4 (word-alignment), and 8 (rows start on double-word boundaries). The initial value is 4.
The following storage parameter affects how pixel data is read from client memory. This value is significant for glTexImage2D
and glTexSubImage2D
:
GL_UNPACK_ALIGNMENT
Specifies the alignment requirements for the start of each pixel row in memory. The allowable values are 1 (byte-alignment), 2 (rows aligned to even-numbered bytes), 4 (word-alignment), and 8 (rows start on double-word boundaries). The initial value is 4.
Pixel storage modes are client states.
glCompressedTexImage2D
and glCompressedTexSubImage2D
are not affected by glPixelStore
.
GL_INVALID_ENUM
is generated if pname
is not an accepted value.
GL_INVALID_VALUE
is generated if alignment is specified as other than 1, 2, 4, or 8.
Copyright © 2003-2004 Silicon Graphics, Inc.
This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.
glReadPixels
, glCompressedTexImage2D
, glCompressedTexSubImage2D
, glTexImage2D
, glTexSubImage2D