GLPIXELMAP(3G) UNIX Programmer's Manual GLPIXELMAP(3G)
NAME
glPixelMapfv, glPixelMapuiv, glPixelMapusv - set up pixel
transfer maps
C SPECIFICATION
void glPixelMapfv( GLenum map,
GLint mapsize,
const GLfloat *values )
void glPixelMapuiv( GLenum map,
GLint mapsize,
const GLuint *values )
void glPixelMapusv( GLenum map,
GLint mapsize,
const GLushort *values )
PARAMETERS
map 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.
mapsize Specifies the size of the map being defined.
values Specifies an array of mapsize 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 com-
mands. Only the specification of the maps is described in
this reference page.
map is a symbolic map name, indicating one of ten maps to
set. mapsize specifies the number of entries in the map, and
values is a pointer to an array of mapsize map values.
The ten maps are as follows:
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GLPIXELMAP(3G) UNIX Programmer's Manual GLPIXELMAP(3G)
GL_PIXEL_MAP_I_TO_I Maps color indices to color
indices.
GL_PIXEL_MAP_S_TO_S Maps stencil indices to sten-
cil indices.
GL_PIXEL_MAP_I_TO_R Maps color indices to red com-
ponents.
GL_PIXEL_MAP_I_TO_G Maps color indices to green
components.
GL_PIXEL_MAP_I_TO_B Maps color indices to blue
components.
GL_PIXEL_MAP_I_TO_A Maps color indices to alpha
components.
GL_PIXEL_MAP_R_TO_R Maps red components to red
components.
GL_PIXEL_MAP_G_TO_G Maps green components to green
components.
GL_PIXEL_MAP_B_TO_B Maps blue components to blue
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 larg-
est 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.
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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 mapsize = 2n for some n or the
results are undefined. The maximum allowable size for each
map depends on the implementation and can be determined by
calling glGet with argument GL_MAX_PIXEL_MAP_TABLE. The sin-
gle maximum applies to all maps; it is at least 32.
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