glPixelMap — set up pixel transfer maps
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);
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.
Specifies the size of the map being defined.
Specifies an array of mapsize values.
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 ARB_imaging subset is supported,
the routines glColorTable, glColorSubTable, glConvolutionFilter1D,
glConvolutionFilter2D, glHistogram, glMinmax, and glSeparableFilter2D. 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.
If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer) while a
pixel transfer map is specified, values is treated as a byte offset into the buffer object's data store.
The ten maps are as follows:
Maps color indices to color indices.
Maps stencil indices to stencil indices.
Maps color indices to red components.
Maps color indices to green components.
Maps color indices to blue components.
Maps color indices to alpha components.
Maps red components to red components.
Maps green components to green components.
Maps blue components to blue components.
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 int 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 |
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 a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target
and the buffer object's data store is currently mapped.
GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the GL_PIXEL_UNPACK_BUFFER target
and the data would be unpacked from the buffer object such that the memory reads required would exceed the data store size.
GL_INVALID_OPERATION is generated by glPixelMapfv if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and values is not evenly divisible into the number of bytes needed to store in memory
a GLfloat datum.
GL_INVALID_OPERATION is generated by glPixelMapuiv if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and values is not evenly divisible into the number of bytes needed to store in memory
a GLuint datum.
GL_INVALID_OPERATION is generated by glPixelMapusv if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and values is not evenly divisible into the number of bytes needed to store in memory
a GLushort datum.
GL_INVALID_OPERATION is generated if glPixelMap is executed between the execution of glBegin and the
corresponding execution of glEnd.
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
glGet with argument GL_PIXEL_UNPACK_BUFFER_BINDING
glColorTable, glColorSubTable, glConvolutionFilter1D, glConvolutionFilter2D, glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glDrawPixels, glHistogram, glMinmax, glPixelStore, glPixelTransfer, glReadPixels, glSeparableFilter2D, glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D