glCopyColorTableEXT

NAME

glCopyColorTableEXT - define a color lookup table from the frame buffer

C SPECIFICATION

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

PARAMETERS

target	Must be one of the following: GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT, or GL_TEXTURE_COLOR_TABLE_EXT.
internalformat	The internal format of the color table. The allowable values are 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_RGB, GL_RGB2, 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, and GL_RGBA16.
x	The x coordinate of the lower-left corner of the frame buffer image to be copied.
y	The y coordinate of the lower-left corner of the frame buffer image to be copied.
width	The number of entries in the color lookup table specified by table. width must be positive and a power of two.

DESCRIPTION

glCopyColorTableEXT is used to specify a color lookup table in exactly the same manner as glColorTableEXT except that the data is obtained from the frame buffer. target must be set to either GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT, or GL_TEXTURE_COLOR_TABLE_EXT. Use glDisable with argument GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT, or GL_TEXTURE_COLOR_TABLE_EXT to enable and disable the corresponding color table.

The x, y, and count correspond to the x, y, and width arguments of glReadPixels; they specify the image width and the lower-left coordinates in the frame buffer. The image is taken from frame buffer exactly as if these arguments were passed to glReadPixels with argument format set to GL_RGBA and height set to 1, stopping after the final expansion to RGBA. If any pixels defined by the region are outside of the window associated with the GL context, the values obtained for those pixels are undefined. Subsequent processing is identical to that of glColorTableEXT.

EXTENSIONS

Some routines and constants for this function are part of an extension, not part of the core GL command set. The following extension names must be present in the string returned by glGetString when called with argument GL_EXTENSIONS to use these routines and constants.

GL_EXT_color_table: glCopyColorTableEXT, GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, and GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT are part of the EXT_color_table extension.
GL_EXT_texture_color_table: GL_TEXTURE_COLOR_TABLE_EXT is part of the EXT_texture_color_table extension.

ERRORS

GL_INVALID_ENUM is generated if target is not an accepted value.

GL_INVALID_ENUM is generated if internalformat is not an accepted value.

GL_INVALID_VALUE is generated if width is less than zero.

GL_TABLE_TOO_LARGE_EXT is generated if the requested color table is too large to be supported by the implementation, and target is not a proxy target.

GL_INVALID_OPERATION is generated if glCopyColorTableEXT is executed between the execution of glEnd.

ASSOCIATED GETS

glGetColorTableEXT
glGetColorTableParameterEXT
glIsEnabled with argument GL_COLOR_TABLE_EXT, GL_POST_CONVOLUTION_COLOR_TABLE_EXT, GL_POST_COLOR_MATRIX_COLOR_TABLE_EXT, or GL_TEXTURE_COLOR_TABLE_EXT