- set up pixel transfer maps
C SPECIFICATION
PARAMETERS
_param1 Specifies a symbolic map name. Must be one of
the following: GL_PIXEL_MAP_I_TO_I,
GL_PIXEL_MAP_S_TO_S, GL_PIXEL_MAP_I_TO_R,
GL_PIXEL_MAP_I_TO_G, GL_PIXEL_MAP_I_TO_B,
GL_PIXEL_MAP_I_TO_A, GL_PIXEL_MAP_R_TO_R,
GL_PIXEL_MAP_G_TO_G, GL_PIXEL_MAP_B_TO_B, or
GL_PIXEL_MAP_A_TO_A.
_param2 Specifies the size of the map being defined.
_param3 Specifies an array of _param2 values.
DESCRIPTION
glPixelMap sets up translation tables, or maps, used by
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D,
glCopyTexSubImage1D, glCopyTexSubImage2D,
glCopyTexSubImage3D, glDrawPixels, glReadPixels,
glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D,
glTexSubImage2D, and glTexSubImage3D. Additionally, if
the GL_ARB_imaging subset is supported, the routines
glColorTable, glColorSubTable, glConvolutionFilter1D,
glConvolutionFilter2D, glHistogram, glMinmax, and
glSeparableFilter2D. Use of these maps is described com-
pletely in the glPixelTransfer reference page, and partly
in the reference pages for the pixel and texture image
commands. Only the specification of the maps is described
in this reference page.
_param1 is a symbolic map name, indicating one of ten maps
to set. _param2 specifies the number of entries in the
map, and _param3 is a pointer to an array of _param2 map
values.
The ten maps are as follows:
GL_PIXEL_MAP_I_TO_I Maps color indices to color
indices.
GL_PIXEL_MAP_S_TO_S Maps stencil indices to
stencil indices.
GL_PIXEL_MAP_I_TO_R Maps color indices to red
components.
GL_PIXEL_MAP_I_TO_G Maps color indices to green
components.
GL_PIXEL_MAP_A_TO_A Maps alpha components to
alpha components.
The entries in a map can be specified as single-precision
floating-point numbers, unsigned short integers, or
unsigned long integers. Maps that store color component
values (all but GL_PIXEL_MAP_I_TO_I and
GL_PIXEL_MAP_S_TO_S) retain their values in floating-point
, with unspecified mantissa and exponent sizes. Floating-
point values specified by glPixelMapfv are converted
directly to the internal floating-point of these maps,
then clamped to the range [0,1]. Unsigned integer values
specified by glPixelMapusv and glPixelMapuiv are converted
linearly such that the largest representable integer maps
to 1.0, and 0 maps to 0.0.
Maps that store indices, GL_PIXEL_MAP_I_TO_I and
GL_PIXEL_MAP_S_TO_S, retain their values in fixed-point ,
with an unspecified number of bits to the right of the
binary point. Floating-point values specified by
glPixelMapfv are converted directly to the internal fixed-
point of these maps. Unsigned integer values specified
by glPixelMapusv and glPixelMapuiv specify integer values,
with all 0's to the right of the binary point.
The following table shows the initial sizes and values for
each of the maps. Maps that are indexed by either color
or stencil indices must have _param2 = 2n for some n or
the results are undefined. The maximum allowable size for
each map depends on the implementation and can be deter-
mined by calling glGet with argument
GL_MAX_PIXEL_MAP_TABLE. The single maximum applies to all
maps; it is at least 32.
GL_PIXEL_MAP_I_TO_B color index B 1 0
GL_PIXEL_MAP_I_TO_A color index A 1 0
GL_PIXEL_MAP_R_TO_R R R 1 0
GL_PIXEL_MAP_G_TO_G G G 1 0
GL_PIXEL_MAP_B_TO_B B B 1 0
GL_PIXEL_MAP_A_TO_A A A 1 0
-------------------------------------------------------------------------------------
ERRORS
GL_INVALID_ENUM is generated if _param1 is not an accepted
value.
GL_INVALID_VALUE is generated if _param2 is less than one
or larger than GL_MAX_PIXEL_MAP_TABLE.
GL_INVALID_VALUE is generated if _param1 is
GL_PIXEL_MAP_I_TO_I, GL_PIXEL_MAP_S_TO_S,
GL_PIXEL_MAP_I_TO_R, GL_PIXEL_MAP_I_TO_G,
GL_PIXEL_MAP_I_TO_B, or GL_PIXEL_MAP_I_TO_A, and _param2
is not a power of two.
GL_INVALID_OPERATION is generated if glPixelMap is exe-
cuted between the execution of glBegin and the correspond-
ing execution of glEnd.
ASSOCIATED GETS
glGetPixelMap
glGet with argument GL_PIXEL_MAP_I_TO_I_SIZE
glGet with argument GL_PIXEL_MAP_S_TO_S_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_I_TO_A_SIZE
glGet with argument GL_PIXEL_MAP_R_TO_R_SIZE
glGet with argument GL_PIXEL_MAP_G_TO_G_SIZE
glGet with argument GL_PIXEL_MAP_B_TO_B_SIZE
glGet with argument GL_PIXEL_MAP_A_TO_A_SIZE
glGet with argument GL_MAX_PIXEL_MAP_TABLE
SEE ALSO
glColorTable, glColorSubTable, glConvolutionFilter1D,
glConvolutionFilter2D, glCopyPixels, glCopyTexImage1D,
glCopyTexImage2D, glCopyTexSubImage1D,
glCopyTexSubImage2D, glDrawPixels, glHistogram, glMinmax,
glPixelStore, glPixelTransfer, glReadPixels,
glSeparableFilter2D, glTexImage1D, glTexImage2D,
glTexImage3D, glTexSubImage1D, glTexSubImage2D,
glTexSubImage3D