fglGetHistogram(3G) OpenGL Reference fglGetHistogram(3G)NAME
fglGetHistogram - get histogram table
FORTRAN SPECIFICATION
SUBROUTINE fglGetHistogram( INTEGER*4 target,
LOGICAL*1 reset,
INTEGER*4 format,
INTEGER*4 type,
CHARACTER*8 values )
PARAMETERS
target Must be GL_HISTOGRAM.
reset If GL_TRUE, each component counter that is actually returned is
reset to zero. (Other counters are unaffected.) If GL_FALSE,
none of the counters in the histogram table is modified.
format The format of values 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_ABGR_EXT, GL_LUMINANCE, or GL_LUMINANCE_ALPHA.
type The type of values 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 histogram table.
DESCRIPTION
fglGetHistogram returns the current histogram table as a one-dimensional
image with the same width as the histogram. No pixel transfer operations
are performed on this image, but pixel storage modes that are applicable
to 1D images are honored.
Color components that are requested in the specified format, but which
are not included in the internal format of the histogram, are returned as
zero.
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fglGetHistogram(3G) OpenGL Reference fglGetHistogram(3G)
The assignments of internal color components to the components requested
by format are:
________________________________________
Internal Component Resulting Component
________________________________________
Red Red
Green Green
Blue Blue
Alpha Alpha
Luminance Red
________________________________________
NOTES
fglGetHistogram is present only if GL_ARB_imaging is returned when
fglGetString is called with an argument of GL_EXTENSIONS.
GL_ABGR_EXT is valid only if the EXT_abgr extension is supported.
ERRORS
GL_INVALID_ENUM is generated if target is not GL_HISTOGRAM.
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 fglGetHistogram is executed between
the execution of fglBegin and the corresponding execution of fglEnd.
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 not GL_RGBA, GL_BGRA or GL_ABGR_EXT.
SEE ALSO
fglHistogram, fglResetHistogram, fglGetHistogramParameter
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