Function glPixelMapfv

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:

• 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 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

Summary

set up pixel transfer maps

See

glPixelMap