1991-2006 Silicon Graphics, Inc.
glGetMinmax 3G
glGetMinmax get minimum and maximum pixel values

## C Specification

void `glGetMinmax` GLenum target GLboolean reset GLenum format GLenum types GLvoid * values

## Parameters

target

  Must be `GL_MINMAX`.

reset

  If `GL_TRUE`, all entries in the minmax table that are actually returned are reset to their initial values. (Other entries are unaltered.) If `GL_FALSE`, the minmax table is unaltered.

format

  The format of the data to be returned in values. Must be one of `GL_RED`, `GL_GREEN`, `GL_BLUE`, `GL_ALPHA`, `GL_RGB`, `GL_BGR`, `GL_RGBA`, `GL_BGRA`, `GL_LUMINANCE`, or `GL_LUMINANCE_ALPHA`.

types

  The type of the data to be returned in values. Symbolic constants `GL_UNSIGNED_BYTE`, `GL_BYTE`, `GL_BITMAP`, `GL_UNSIGNED_SHORT`, `GL_SHORT`, `GL_UNSIGNED_INT`, `GL_INT`, `GL_FLOAT`, `GL_UNSIGNED_BYTE_3_3_2`, `GL_UNSIGNED_BYTE_2_3_3_REV`, `GL_UNSIGNED_SHORT_5_6_5`, `GL_UNSIGNED_SHORT_5_6_5_REV`, `GL_UNSIGNED_SHORT_4_4_4_4`, `GL_UNSIGNED_SHORT_4_4_4_4_REV`, `GL_UNSIGNED_SHORT_5_5_5_1`, `GL_UNSIGNED_SHORT_1_5_5_5_REV`, `GL_UNSIGNED_INT_8_8_8_8`, `GL_UNSIGNED_INT_8_8_8_8_REV`, `GL_UNSIGNED_INT_10_10_10_2`, and `GL_UNSIGNED_INT_2_10_10_10_REV` are accepted.

values

  A pointer to storage for the returned values.

## Description

`glGetMinmax` returns the accumulated minimum and maximum pixel values (computed on a per-component basis) in a one-dimensional image of width 2. The first set of return values are the minima, and the second set of return values are the maxima. The format of the return values is determined by format, and their type is determined by types.

If a non-zero named buffer object is bound to the `GL_PIXEL_PACK_BUFFER` target (see glBindBuffer) while minimum and maximum pixel values are requested, values is treated as a byte offset into the buffer object's data store.

No pixel transfer operations are performed on the return values, but pixel storage modes that are applicable to one-dimensional images are performed. Color components that are requested in the specified format, but that are not included in the internal format of the minmax table, are returned as zero. The assignment of internal color components to the components requested by format are as follows:

Internal Component | Resulting Component
--- | ---
Red | Red
Green | Green
Blue | Blue
Alpha | Alpha
Luminance | Red

If reset is `GL_TRUE`, the minmax table entries corresponding to the return values are reset to their initial values. Minimum and maximum values that are not returned are not modified, even if reset is `GL_TRUE`.

## Notes

`glGetMinmax` is present only if `ARB_imaging` is returned when glGetString is called with an argument of `GL_EXTENSIONS`.

## Errors

`GL_INVALID_ENUM` is generated if target is not `GL_MINMAX`.

`GL_INVALID_ENUM` is generated if format is not one of the allowable values.

`GL_INVALID_ENUM` is generated if types is not one of the allowable values.

`GL_INVALID_OPERATION` is generated if types is one of `GL_UNSIGNED_BYTE_3_3_2`, `GL_UNSIGNED_BYTE_2_3_3_REV`, `GL_UNSIGNED_SHORT_5_6_5`, or `GL_UNSIGNED_SHORT_5_6_5_REV` and format is not `GL_RGB`.

`GL_INVALID_OPERATION` is generated if types is one of `GL_UNSIGNED_SHORT_4_4_4_4`, `GL_UNSIGNED_SHORT_4_4_4_4_REV`, `GL_UNSIGNED_SHORT_5_5_5_1`, `GL_UNSIGNED_SHORT_1_5_5_5_REV`, `GL_UNSIGNED_INT_8_8_8_8`, `GL_UNSIGNED_INT_8_8_8_8_REV`, `GL_UNSIGNED_INT_10_10_10_2`, or `GL_UNSIGNED_INT_2_10_10_10_REV` and format is neither `GL_RGBA` nor `GL_BGRA`.

`GL_INVALID_OPERATION` is generated if a non-zero buffer object name is bound to the `GL_PIXEL_PACK_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_PACK_BUFFER` target and the data would be packed to the buffer object such that the memory writes required would exceed the data store size.

`GL_INVALID_OPERATION` is generated if a non-zero buffer object name is bound to the `GL_PIXEL_PACK_BUFFER` target and values is not evenly divisible into the number of bytes needed to store in memory a datum indicated by type.

`GL_INVALID_OPERATION` is generated if `glGetMinmax` is executed between the execution of glBegin and the corresponding execution of glEnd.

## Associated Gets

glGetMinmaxParameter

glGet with argument `GL_PIXEL_PACK_BUFFER_BINDING`

## See Also

glMinmax, glResetMinmax,

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.