1GLGETHISTOGRAM(3G)                                          GLGETHISTOGRAM(3G)
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NAME

6       glGetHistogram - get histogram table
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C SPECIFICATION

10       void glGetHistogram( GLenum target,
11                            GLboolean reset,
12                            GLenum format,
13                            GLenum type,
14                            GLvoid *values )
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PARAMETERS

18       target  Must be GL_HISTOGRAM.
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20       reset   If GL_TRUE, each component counter that is actually returned is
21               reset to zero.  (Other counters are unaffected.)  If  GL_FALSE,
22               none of the counters in the histogram table is modified.
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24       format  The   of  values  to  be  returned  in  values.  Must be one of
25               GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,  GL_BGR,  GL_RGBA,
26               GL_BGRA, GL_LUMINANCE, or GL_LUMINANCE_ALPHA.
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28       type    The  type  of  values  to be returned in values.  Symbolic con‐
29               stants GL_UNSIGNED_BYTE, GL_BYTE, GL_BITMAP, GL_UNSIGNED_SHORT,
30               GL_SHORT,        GL_UNSIGNED_INT,       GL_INT,       GL_FLOAT,
31               GL_UNSIGNED_BYTE_3_3_2,             GL_UNSIGNED_BYTE_2_3_3_REV,
32               GL_UNSIGNED_SHORT_5_6_5,           GL_UNSIGNED_SHORT_5_6_5_REV,
33               GL_UNSIGNED_SHORT_4_4_4_4,       GL_UNSIGNED_SHORT_4_4_4_4_REV,
34               GL_UNSIGNED_SHORT_5_5_5_1,       GL_UNSIGNED_SHORT_1_5_5_5_REV,
35               GL_UNSIGNED_INT_8_8_8_8,           GL_UNSIGNED_INT_8_8_8_8_REV,
36               GL_UNSIGNED_INT_10_10_10_2,  and GL_UNSIGNED_INT_2_10_10_10_REV
37               are accepted.
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39       values  A pointer to storage for the returned histogram table.
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DESCRIPTION

42       glGetHistogram returns the current histogram table as a one-dimensional
43       image  with  the same width as the histogram.  No pixel transfer opera‐
44       tions are performed on this image, but pixel  storage  modes  that  are
45       applicable to 1D images are honored.
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47       Color  components that are requested in the specified format, but which
48       are not included in the internal  of the  histogram,  are  returned  as
49       zero.
50       The   assignments  of  internal  color  components  to  the  components
51       requested by format are:
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53                      ─────────────────────────────────────────
54                      Internal Component   Resulting Component
55                      ─────────────────────────────────────────
56                      Red                  Red
57                      Green                Green
58                      Blue                 Blue
59                      Alpha                Alpha
60                      Luminance            Red
61                      ─────────────────────────────────────────
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NOTES

65       glGetHistogram is present  only  if  GL_ARB_imaging  is  returned  when
66       glGetString is called with an argument of GL_EXTENSIONS.
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ERRORS

69       GL_INVALID_ENUM is generated if target is not GL_HISTOGRAM.
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71       GL_INVALID_ENUM is generated if format is not one of the allowable val‐
72       ues.
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74       GL_INVALID_ENUM is generated if type is not one of the  allowable  val‐
75       ues.
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77       GL_INVALID_OPERATION is generated if glGetHistogram is executed between
78       the execution of glBegin and the corresponding execution of glEnd.
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80       GL_INVALID_OPERATION   is    generated    if    type    is    one    of
81       GL_UNSIGNED_BYTE_3_3_2,                     GL_UNSIGNED_BYTE_2_3_3_REV,
82       GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and  format  is
83       not GL_RGB.
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85       GL_INVALID_OPERATION    is    generated    if    type    is    one   of
86       GL_UNSIGNED_SHORT_4_4_4_4,               GL_UNSIGNED_SHORT_4_4_4_4_REV,
87       GL_UNSIGNED_SHORT_5_5_5_1,               GL_UNSIGNED_SHORT_1_5_5_5_REV,
88       GL_UNSIGNED_INT_8_8_8_8,                   GL_UNSIGNED_INT_8_8_8_8_REV,
89       GL_UNSIGNED_INT_10_10_10_2,  or GL_UNSIGNED_INT_2_10_10_10_REV and for‐
90       mat is neither GL_RGBA nor GL_BGRA.
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SEE ALSO

93       glHistogram(3G), glResetHistogram(3G), glGetHistogramParameter(3G)
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97                                                            GLGETHISTOGRAM(3G)