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'\" t
'\"! tbl | mmdoc
'\"macro stdmacro
.ds Vn Version 1.2
.ds Dt 24 September 1999
.ds Re Release 1.2.1
.ds Dp Jan 14 18:30
.ds Dm 01 gethistog
.ds Xs 52081 6 gethistogram.gl
.TH GLGETHISTOGRAM 3G
.SH NAME
.B "glGetHistogram
\- get histogram table
.SH C SPECIFICATION
void \f3glGetHistogram\fP(
GLenum \fItarget\fP,
.nf
.ta \w'\f3void \fPglGetHistogram( 'u
GLboolean \fIreset\fP,
GLenum \fIformat\fP,
GLenum \fItype\fP,
GLvoid \fI*values\fP )
.fi
.SH PARAMETERS
.TP \w'\f2target\fP\ \ 'u
\f2target\fP
Must be
\%\f3GL_HISTOGRAM\fP.
.TP
\f2reset\fP
If \%\f3GL_TRUE\fP, each component counter that is actually returned
is reset to zero. (Other counters are unaffected.)
If \%\f3GL_FALSE\fP, none of the counters in the histogram table is modified.
.TP
\f2format\fP
The of values to be returned in \f2values\fP.
Must be one of
\%\f3GL_RED\fP,
\%\f3GL_GREEN\fP,
\%\f3GL_BLUE\fP,
\%\f3GL_ALPHA\fP,
\%\f3GL_RGB\fP,
\%\f3GL_BGR\fP,
\%\f3GL_RGBA\fP,
\%\f3GL_BGRA\fP,
\%\f3GL_LUMINANCE\fP, or
\%\f3GL_LUMINANCE_ALPHA\fP.
.TP
\f2type\fP
The type of values to be returned in \f2values\fP.
Symbolic constants
\%\f3GL_UNSIGNED_BYTE\fP,
\%\f3GL_BYTE\fP,
\%\f3GL_BITMAP\fP,
\%\f3GL_UNSIGNED_SHORT\fP,
\%\f3GL_SHORT\fP,
\%\f3GL_UNSIGNED_INT\fP,
\%\f3GL_INT\fP,
\%\f3GL_FLOAT\fP,
\%\f3GL_UNSIGNED_BYTE_3_3_2\fP,
\%\f3GL_UNSIGNED_BYTE_2_3_3_REV\fP,
\%\f3GL_UNSIGNED_SHORT_5_6_5\fP,
\%\f3GL_UNSIGNED_SHORT_5_6_5_REV\fP,
\%\f3GL_UNSIGNED_SHORT_4_4_4_4\fP,
\%\f3GL_UNSIGNED_SHORT_4_4_4_4_REV\fP,
\%\f3GL_UNSIGNED_SHORT_5_5_5_1\fP,
\%\f3GL_UNSIGNED_SHORT_1_5_5_5_REV\fP,
\%\f3GL_UNSIGNED_INT_8_8_8_8\fP,
\%\f3GL_UNSIGNED_INT_8_8_8_8_REV\fP,
\%\f3GL_UNSIGNED_INT_10_10_10_2\fP, and
\%\f3GL_UNSIGNED_INT_2_10_10_10_REV\fP
are accepted.
.TP
\f2values\fP
A pointer to storage for the returned histogram table.
.SH DESCRIPTION
\%\f3glGetHistogram\fP 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.
.PP
Color components that are requested in the specified \f2format\fP, but which
are not included in the internal of the histogram, are returned as
zero.
.bp
The assignments of internal color components to the components
requested by \f2format\fP are:
.TS
center;
lb lb
l l.
_
Internal Component Resulting Component
_
Red Red
Green Green
Blue Blue
Alpha Alpha
Luminance Red
_
.TE
.SH NOTES
\%\f3glGetHistogram\fP is present only if \%\f3GL_ARB_imaging\fP is returned when \%\f3glGetString\fP
is called with an argument of \%\f3GL_EXTENSIONS\fP.
.SH ERRORS
\%\f3GL_INVALID_ENUM\fP is generated if \f2target\fP is not \%\f3GL_HISTOGRAM\fP.
.P
\%\f3GL_INVALID_ENUM\fP is generated if \f2format\fP is not one of the allowable
values.
.P
\%\f3GL_INVALID_ENUM\fP is generated if \f2type\fP is not one of the allowable
values.
.P
\%\f3GL_INVALID_OPERATION\fP is generated if \%\f3glGetHistogram\fP is executed
between the execution of \%\f3glBegin\fP and the corresponding
execution of \%\f3glEnd\fP.
.P
.P
\%\f3GL_INVALID_OPERATION\fP is generated if \f2type\fP is one of
\%\f3GL_UNSIGNED_BYTE_3_3_2\fP,
\%\f3GL_UNSIGNED_BYTE_2_3_3_REV\fP,
\%\f3GL_UNSIGNED_SHORT_5_6_5\fP, or
\%\f3GL_UNSIGNED_SHORT_5_6_5_REV\fP
and \f2format\fP is not \%\f3GL_RGB\fP.
.P
\%\f3GL_INVALID_OPERATION\fP is generated if \f2type\fP is one of
\%\f3GL_UNSIGNED_SHORT_4_4_4_4\fP,
\%\f3GL_UNSIGNED_SHORT_4_4_4_4_REV\fP,
\%\f3GL_UNSIGNED_SHORT_5_5_5_1\fP,
\%\f3GL_UNSIGNED_SHORT_1_5_5_5_REV\fP,
\%\f3GL_UNSIGNED_INT_8_8_8_8\fP,
\%\f3GL_UNSIGNED_INT_8_8_8_8_REV\fP,
\%\f3GL_UNSIGNED_INT_10_10_10_2\fP, or
\%\f3GL_UNSIGNED_INT_2_10_10_10_REV\fP
and \f2format\fP is neither \%\f3GL_RGBA\fP nor \%\f3GL_BGRA\fP.
.SH SEE ALSO
\%\f3glHistogram(3G)\fP,
\%\f3glResetHistogram(3G)\fP,
\%\f3glGetHistogramParameter(3G)\fP
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