GLGETHISTOGRAM(3G)GLGETHISTOGRAM(3G)NAMEglGetHistogram - get histogram table
C SPECIFICATION
void glGetHistogram( GLenum target,
GLboolean reset,
GLenum format,
GLenum type,
GLvoid *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 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_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.
DESCRIPTIONglGetHistogram 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 of the histogram, are returned as
zero. 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
-----------------------------------------
NOTESglGetHistogram 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_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 glGetHistogram 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 ALSOglHistogram(3G), glResetHistogram(3G), glGetHistogramParameter(3G)
March 1, 2011
