NAME
glPixelMapfv, glPixelMapuiv, glPixelMapusv - set up pixel
transfer maps
C SPECIFICATION
void glPixelMapfv( GLenum map,
GLsizei mapsize,
const GLfloat *values )
void glPixelMapuiv( GLenum map,
GLsizei mapsize,
const GLuint *values )
void glPixelMapusv( GLenum map,
GLsizei 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, glDrawPixels,
glReadPixels, glTexImage1D, glTexImage2D, glTexSubImage1D,
and glTexSubImage2D. Use of these maps is described
completely 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.
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:
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_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 format, with unspecified
mantissa and exponent sizes. Floating-point values
specified by glPixelMapfv are converted directly to the
internal floating-point format 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
format, 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 format 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 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
single maximum applies to all maps; it is at least 32.
______________________________________________________________________________________
| map | lookup index | lookup value | initial size | initial value |
|____________________|________________|________________|______________|_______________|
|GL_PIXEL_MAP_I_TO_I | color index | color index | 1 | 0 |
|GL_PIXEL_MAP_S_TO_S | stencil index | stencil index | 1 | 0 |
|GL_PIXEL_MAP_I_TO_R | color index | R | 1 | 0 |
|GL_PIXEL_MAP_I_TO_G | color index | G | 1 | 0 |
|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 map is not an accepted
value.
GL_INVALID_VALUE is generated if mapsize is less than one or
larger than GL_MAX_PIXEL_MAP_TABLE.
GL_INVALID_VALUE is generated if map 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 mapsize is not a power of two.
GL_INVALID_OPERATION is generated if glPixelMap is executed
between the execution of glBegin and the corresponding
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
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D,
glCopyTexSubImage1D, glCopyTexSubImage2D, glDrawPixels,
glPixelStore, glPixelTransfer, glReadPixels, glTexImage1D,
glTexImage2D, glTexSubImage1D, glTexSubImage2D