GLCOPYCOLORTABLE(3G) OpenGL 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 format of the texture image. Must be one of the following symbolic constants: 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, or
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()).
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 format specified by
internalformat. This conversion simply maps the component values of the pixel (R, G, B, and A) to the values included in the internal
format (red, green, blue, alpha, luminance, and intensity). The mapping is as follows:
+---------------------------------+-----------------------------+-------------------------------+------------------------------+-------------------------------+-----------------------------------+-----------------------------------+
| | | | | | | |
| Internal | Red | Green | Blue | Alpha | Luminance | Intensity |
|Format | | | | | | |
| | | | | | | |
+---------------------------------+-----------------------------+-------------------------------+------------------------------+-------------------------------+-----------------------------------+-----------------------------------+
|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 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.
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(), glColorTableParameter(), glReadPixels()
COPYRIGHT
Copyright (C) 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see
http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 06/10/2014 GLCOPYCOLORTABLE(3G)