glpixelmap - Man Page
glPixelMap(3G) OpenGL Reference 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 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.
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glPixelMap(3G) OpenGL Reference glPixelMap(3G)
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 = 2n 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.
______________________________________________________________________________________
|____________________|________________|________________|______________|_______________|
|GL_PIXEL_MAP_I_TO_I | color index | color index | 1 | 0.0 |
|GL_PIXEL_MAP_S_TO_S | stencil index | stencil index | 1 | 0 |
|GL_PIXEL_MAP_I_TO_R | color index | R | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_G | color index | G | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_B | color index | B | 1 | 0.0 |
|GL_PIXEL_MAP_I_TO_A | color index | A | 1 | 0.0 |
|GL_PIXEL_MAP_R_TO_R | R | R | 1 | 0.0 |
|GL_PIXEL_MAP_G_TO_G | G | G | 1 | 0.0 |
|GL_PIXEL_MAP_B_TO_B | B | B | 1 | 0.0 |
|GL_PIXEL_MAP_A_TO_A | A | A | 1 | 0.0 |
|____________________|________________|________________|______________|_______________|
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glPixelMap(3G) OpenGL Reference glPixelMap(3G)
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
MACHINE DEPENDENCIES
The following problems are known to exist on InfiniteReality systems.
All should be fixed in the next software release.
1. The GL_INDEX_SHIFT and GL_INDEX_OFFSET pixel transfer operations
are not applied properly in some cases when GL_MAP_COLOR is
enabled.
2. Incorrect results are produced if the I-to-I pixel map contains
entries with negative values.
3. Incorrect results are produced if the I-to-RGBA pixel map or the
RGBA-to-RGBA pixel maps contain values that are outside the
range [0.0,1.0].
SEE ALSO
glCopyPixels, glDrawPixels, glPixelStore, glPixelTransfer, glReadPixels,
glTexImage1D, glTexImage2D
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