1GLGETHISTOGRAM(3G) GLGETHISTOGRAM(3G)
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6 glGetHistogram - get histogram table
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10 void glGetHistogram( GLenum target,
11 GLboolean reset,
12 GLenum format,
13 GLenum type,
14 GLvoid *values )
15
18 target Must be GL_HISTOGRAM.
19 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.
23 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.
27 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.
38 values A pointer to storage for the returned histogram table.
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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.
46 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:
52 ─────────────────────────────────────────
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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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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69 GL_INVALID_ENUM is generated if target is not GL_HISTOGRAM.
70 GL_INVALID_ENUM is generated if format is not one of the allowable val‐
72 ues.
73 GL_INVALID_ENUM is generated if type is not one of the allowable val‐
75 ues.
76 GL_INVALID_OPERATION is generated if glGetHistogram is executed between
78 the execution of glBegin and the corresponding execution of glEnd.
79 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.
84 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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93 glHistogram(3G), glResetHistogram(3G), glGetHistogramParameter(3G)
94 GLGETHISTOGRAM(3G)