MirBSD manpage: glCopyColorTable(3)


GLCOPYCOLORTABLE(3G)UNIX Programmer's Manual GLCOPYCOLORTABLE(3G)

NAME

     glCopyColorTable - copy pixels into a color table

C SPECIFICATION

     void glCopyColorTable( GLenum target,
                            GLenum internalformat,
                            GLint x,
                            GLint y,
                            GLsizei width )

PARAMETERS

     target          The color table target. Must be
                     GL_COLOR_TABLE,
                     GL_POST_CONVOLUTION_COLOR_TABLE, or
                     GL_POST_COLOR_MATRIX_COLOR_TABLE.

     internalformat  The internal storage  of the texture image.
                     Must be one of the following symbolic con-
                     stants: GL_ALPHA, GL_ALPHA4, GL_ALPHA8,
                     GL_ALPHA12, GL_ALPHA16, GL_LUMINANCE,
                     GL_LUMINANCE4, GL_LUMINANCE8,
                     GL_LUMINANCE12, GL_LUMINANCE16,
                     GL_LUMINANCE_ALPHA, GL_LUMINANCE4_ALPHA4,
                     GL_LUMINANCE6_ALPHA2, GL_LUMINANCE8_ALPHA8,
                     GL_LUMINANCE12_ALPHA4,
                     GL_LUMINANCE12_ALPHA12,
                     GL_LUMINANCE16_ALPHA16, GL_INTENSITY,
                     GL_INTENSITY4, GL_INTENSITY8,
                     GL_INTENSITY12, GL_INTENSITY16, GL_R3_G3_B2,
                     GL_RGB, GL_RGB4, GL_RGB5, GL_RGB8, GL_RGB10,
                     GL_RGB12, GL_RGB16, GL_RGBA, GL_RGBA2,
                     GL_RGBA4, GL_RGB5_A1, GL_RGBA8, GL_RGB10_A2,
                     GL_RGBA12, GL_RGBA16.

     x               The x coordinate of the lower-left corner of
                     the pixel rectangle to be transferred to the
                     color table.

     y               The y coordinate of the lower-left corner of
                     the pixel rectangle to be transferred to the
                     color table.

     width           The width of the pixel rectangle.

DESCRIPTION

     glCopyColorTable loads a color table with pixels from the
     current GL_READ_BUFFER (rather than from main memory, as is
     the case for glColorTable).

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GLCOPYCOLORTABLE(3G)UNIX Programmer's Manual GLCOPYCOLORTABLE(3G)

     The screen-aligned pixel rectangle with lower-left corner at
     (x, y) having width width and height 1 is loaded into the
     color table. If any pixels within this region are outside
     the window that is associated with the GL context, the
     values obtained for those pixels are undefined.

     The pixels in the rectangle are processed just as if
     glReadPixels were called, with internalformat set to RGBA,
     but processing stops after the final conversion to RGBA.

     The four scale parameters and the four bias parameters that
     are defined for the table are then used to scale and bias
     the R, G, B, and A components of each pixel. The scale and
     bias parameters are set by calling glColorTableParameter.

     Next, the R, G, B, and A values are clamped to the range
     [0,1]. Each pixel is then converted to the internal  speci-
     fied by internalformat. This conversion simply maps the com-
     ponent values of the pixel (R, G, B, and A) to the values
     included in the internal  (red, green, blue, alpha, lumi-
     nance, and intensity).  The mapping is as follows:

_______________________________________________________________________

Internal Format Red Green Blue Alpha Luminance Intensity

_______________________________________________________________________

GL_ALPHA A

GL_LUMINANCE R

GL_LUMINANCE_ALPHA A R

GL_INTENSITY R

GL_RGB R G B

GL_RGBA R G B A

_______________________________________________________________________


     Finally, the red, green, blue, alpha, luminance, and/or
     intensity components of the resulting pixels are stored in
     the color table. They form a one-dimensional table with
     indices in the range [0, width - 1].

NOTES

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

ERRORS

     GL_INVALID_ENUM is generated when target is not one of the
     allowable values.

     GL_INVALID_VALUE is generated if width is less than zero.

     GL_INVALID_VALUE is generated if internalformat is not one
     of the allowable values.

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GLCOPYCOLORTABLE(3G)UNIX Programmer's Manual GLCOPYCOLORTABLE(3G)

     GL_TABLE_TOO_LARGE is generated if the requested color table
     is too large to be supported by the implementation.

     GL_INVALID_OPERATION is generated if glCopyColorTable is
     executed between the execution of glBegin and the
     corresponding execution of glEnd.

ASSOCIATED GETS

     glGetColorTable, glGetColorTableParameter

SEE ALSO

     glColorTable(3G), glColorTableParameter(3G),
     glReadPixels(3G)

MirBSD #10-current     Printed 2021-12-07                       3

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