glPixelMap
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## 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`);`

## Python Specification

``glPixelMapfv`` | `(` | ``map`, `mapsize`, `values`) → `None``
``glPixelMapuiv`` | `(` | ``map`, `mapsize`, `values`) → `None``
``glPixelMapusv`` | `(` | ``map`, `mapsize`, `values`) → `None``

## 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 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, glColorSubTable, glConvolutionFilter1D, glConvolutionFilter2D, glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glDrawPixels, glHistogram, glMinmax, glPixelStore, glPixelTransfer, glReadPixels, glSeparableFilter2D, glTexImage1D, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D

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