GLGETMINMAX(3G)

NAME
glGetMinmax - get minimum and maximum pixel values

C SPECIFICATION
void glGetMinmax( GLenum target,
	GLboolean reset,
	GLenum format,
	GLenum type,
	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 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.

type
    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 of the return values is determined by format, and their type is determined by type.

No pixel transfer operations are performed on the return values, but pixel storage modes that are applicable to 1-dimensional images are performed. Color components that are requested in the specified format, but that are not included in the internal 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 GL_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 type is not one of the allowable values.

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

GL_INVALID_OPERATION is generated if type 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 type 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.

SEE ALSO
glMinmax, glResetMinmax, glGetMinmaxParameter