glPixelMap
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
glDrawPixels,
glReadPixels,
glCopyPixels,
glTexImage1D, and
glTexImage2D.
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 zero 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 zeros to the
right of the binary point.
The table below shows the initial sizes and values for each of the maps.
Maps that are indexed by either color or stencil indices must have
mapsize = 2^n for some n or 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, and it is at least 32.
ERRORS
GL_INVALID_ENUM is generated if map is not an accepted value.
GL_INVALID_VALUE is generated if mapsize is negative 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 called between
a call to glBegin and the corresponding
call to 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,
glDrawPixels,
glPixelStore,
glPixelTransfer,
glReadPixels,
glTexImage1D,
glTexImage2D
back to the OpenGL index page
© 1995 Uwe Behrens. All rights reserved.