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 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 , 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 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 , 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.

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 = $2 sup n$ 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
glColorTable(3G), glColorSubTable(3G), glConvolutionFilter1D(3G), glConvolutionFilter2D(3G), glCopyPixels(3G), glCopyTexImage1D(3G), glCopyTexImage2D(3G), glCopyTexSubImage1D(3G), glCopyTexSubImage2D(3G), glDrawPixels(3G), glHistogram(3G), glMinmax(3G), glPixelStore(3G), glPixelTransfer(3G), glReadPixels(3G), glSeparableFilter2D(3G), glTexImage1D(3G), glTexImage2D(3G), glTexImage3D(3G), glTexSubImage1D(3G), glTexSubImage2D(3G), glTexSubImage3D(3G)