glCopyColorTable(3gl)

1GLCOPYCOLORTABLE(3G)                                      GLCOPYCOLORTABLE(3G)
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NAME

6       glCopyColorTable - copy pixels into a color table
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C SPECIFICATION

10       void glCopyColorTable( GLenum target,
11                              GLenum internalformat,
12                              GLint x,
13                              GLint y,
14                              GLsizei width )
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PARAMETERS

18       target          The   color   table  target.  Must  be  GL_COLOR_TABLE,
19                       GL_POST_CONVOLUTION_COLOR_TABLE,                     or
20                       GL_POST_COLOR_MATRIX_COLOR_TABLE.
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22       internalformat  The  internal  storage   of the texture image.  Must be
23                       one of  the  following  symbolic  constants:  GL_ALPHA,
24                       GL_ALPHA4,     GL_ALPHA8,    GL_ALPHA12,    GL_ALPHA16,
25                       GL_LUMINANCE,       GL_LUMINANCE4,       GL_LUMINANCE8,
26                       GL_LUMINANCE12,   GL_LUMINANCE16,   GL_LUMINANCE_ALPHA,
27                       GL_LUMINANCE4_ALPHA4,             GL_LUMINANCE6_ALPHA2,
28                       GL_LUMINANCE8_ALPHA8,            GL_LUMINANCE12_ALPHA4,
29                       GL_LUMINANCE12_ALPHA12,         GL_LUMINANCE16_ALPHA16,
30                       GL_INTENSITY,       GL_INTENSITY4,       GL_INTENSITY8,
31                       GL_INTENSITY12,  GL_INTENSITY16,  GL_R3_G3_B2,  GL_RGB,
32                       GL_RGB4,    GL_RGB5,   GL_RGB8,   GL_RGB10,   GL_RGB12,
33                       GL_RGB16,  GL_RGBA,  GL_RGBA2,  GL_RGBA4,   GL_RGB5_A1,
34                       GL_RGBA8, GL_RGB10_A2, GL_RGBA12, GL_RGBA16.
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36       x               The  x coordinate of the lower-left corner of the pixel
37                       rectangle to be transferred to the color table.
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39       y               The y coordinate of the lower-left corner of the  pixel
40                       rectangle to be transferred to the color table.
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42       width           The width of the pixel rectangle.
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DESCRIPTION

45       glCopyColorTable  loads  a  color  table  with  pixels from the current
46       GL_READ_BUFFER (rather than from  main  memory,  as  is  the  case  for
47       glColorTable).
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49       The  screen-aligned  pixel  rectangle  with lower-left corner at (x, y)
50       having width width and height 1 is loaded into the color table. If  any
51       pixels  within  this  region  are outside the window that is associated
52       with the GL context, the values obtained for  those  pixels  are  unde‐
53       fined.
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55       The  pixels in the rectangle are processed just as if glReadPixels were
56       called, with internalformat set to RGBA, but processing stops after the
57       final conversion to RGBA.
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59       The four scale parameters and the four bias parameters that are defined
60       for the table are then used to scale and bias the R, G, B, and A compo‐
61       nents  of  each pixel. The scale and bias parameters are set by calling
62       glColorTableParameter.
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64       Next, the R, G, B, and A values are clamped to the range  [0,1].   Each
65       pixel  is  then converted to the internal  specified by internalformat.
66       This conversion simply maps the component values of the pixel (R, G, B,
67       and  A)  to  the  values  included  in the internal  (red, green, blue,
68       alpha, luminance, and intensity).  The mapping is as follows:
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70       ────────────────────────────────────────────────────────────────────────
71       Internal Format      Red   Green   Blue   Alpha   Luminance   Intensity
72       ────────────────────────────────────────────────────────────────────────
73       GL_ALPHA                                    A
74       GL_LUMINANCE                                          R
75       GL_LUMINANCE_ALPHA                          A         R
76       GL_INTENSITY                                                      R
77       GL_RGB                R      G      B
78       GL_RGBA               R      G      B       A
79       ────────────────────────────────────────────────────────────────────────
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81       Finally, the red, green, blue, alpha, luminance, and/or intensity  com‐
82       ponents  of  the  resulting pixels are stored in the color table.  They
83       form a one-dimensional table with indices in the range [0, width - 1].
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NOTES

86       glCopyColorTable is available only if GL_ARB_imaging is  returned  from
87       calling glGetString with an argument of GL_EXTENSIONS.
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ERRORS

90       GL_INVALID_ENUM  is  generated  when target is not one of the allowable
91       values.
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93       GL_INVALID_VALUE is generated if width is less than zero.
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95       GL_INVALID_VALUE is generated if  internalformat  is  not  one  of  the
96       allowable values.
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98       GL_TABLE_TOO_LARGE  is  generated  if  the requested color table is too
99       large to be supported by the implementation.
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101       GL_INVALID_OPERATION  is  generated  if  glCopyColorTable  is  executed
102       between  the  execution  of  glBegin and the corresponding execution of
103       glEnd.
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ASSOCIATED GETS

106       glGetColorTable, glGetColorTableParameter
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