GLenum internalforma )
PARAMETERS
target Must be one of GL_COLOR_TABLE,
GL_POST_CONVOLUTION_COLOR_TABLE,
GL_POST_COLOR_MATRIX_COLOR_TABLE, GL_PROXY_COLOR_TABLE,
GL_PROXY_POST_CONVOLUTION_COLOR_TABLE, or
GL_PROXY_POST_COLOR_MATRIX_COLOR_TABLE.
internalforma 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_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, and GL_RGBA16.
_param3 The number of entries in the color lookup table specified
by _param6.
_param4 The format of the pixel data in _param6. The allowable
values are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA,
GL_LUMINANCE, GL_LUMINANCE_ALPHA, GL_RGB, GL_BGR,
GL_RGBA, and GL_BGRA.
_param5 The type of the pixel data in _param6. The allowable
values are GL_UNSIGNED_BYTE, GL_BYTE, GL_UNSIGNED_SHORT,
GL_SHORT, GL_UNSIGNED_INT, GL_INT, GL_FLOAT,
GL_UNSIGNED_BYTE_3_3_2, GL_UNSIGNED_BYTE_2_3_3_REV,
GL_UNSIGNED_SHORT_5_6_5, GL_UNSIGNED_SHORT_5_6_5_REV,
GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_4_4_4_4_REV,
GL_UNSIGNED_SHORT_5_5_5_1, GL_UNSIGNED_SHORT_1_5_5_5_REV,
GL_UNSIGNED_INT_8_8_8_8, GL_UNSIGNED_INT_8_8_8_8_REV,
GL_UNSIGNED_INT_10_10_10_2, and
GL_UNSIGNED_INT_2_10_10_10_REV.
_param6 Pointer to a one-dimensional array of pixel data that is
processed to build the color table.
DESCRIPTION
glColorTable may be used in two ways: to test the actual size and color
resolution of a lookup table given a particular set of parameters, or to
load the contents of a color lookup table. Use the targets GL_PROXY_*
for the first case and the other targets for the second case.
If target is GL_COLOR_TABLE, GL_POST_CONVOLUTION_COLOR_TABLE, or
GL_POST_COLOR_MATRIX_COLOR_TABLE, glColorTable builds a color lookup ta‐
green, blue, alpha, luminance, and intensity). The mapping is as fol‐
lows:
────────────────────────────────────────────────────────────────────────
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 compo‐
nents of the resulting pixels are stored in the color table. They form
a one-dimensional table with indices in the range [0, _param3 - 1].
If target is GL_PROXY_*, glColorTable recomputes and stores the values
of the proxy color table's state variables GL_COLOR_TABLE_FORMAT,
GL_COLOR_TABLE_WIDTH, GL_COLOR_TABLE_RED_SIZE,
GL_COLOR_TABLE_GREEN_SIZE, GL_COLOR_TABLE_BLUE_SIZE,
GL_COLOR_TABLE_ALPHA_SIZE, GL_COLOR_TABLE_LUMINANCE_SIZE, and
GL_COLOR_TABLE_INTENSITY_SIZE. There is no effect on the image or state
of any actual color table. If the specified color table is too large to
be supported, then all the proxy state variables listed above are set to
zero. Otherwise, the color table could be supported by glColorTable us‐
ing the corresponding non-proxy target, and the proxy state variables
are set as if that target were being defined.
The proxy state variables can be retrieved by calling
glGetColorTableParameter with a target of GL_PROXY_*. This allows the
application to decide if a particular glColorTable command would suc‐
ceed, and to determine what the resulting color table attributes would
be.
If a color table is enabled, and its width is non-zero, then its con‐
tents are used to replace a subset of the components of each RGBA pixel
group, based on the internal format of the table.
Each pixel group has color components (R, G, B, A) that are in the range
[0.0, 1.0]. The color components are rescaled to the size of the color
lookup table to form an index. Then a subset of the components based on
the internal format of the table are replaced by the table entry se‐
lected by that index. If the color components and contents of the table
are represented as follows:
──────────────────────────────────────────────────
Representation Meaning
──────────────────────────────────────────────────
r Table index computed from R
g Table index computed from G
Resulting Texture Components
Table Internal Format R G B A
─────────────────────────────────────────────────────
GL_ALPHA R G B A[a]
GL_LUMINANCE L[r] L[g] L[b] At
GL_LUMINANCE_ALPHA L[r] L[g] L[b] A[a]
GL_INTENSITY I[r] I[g] I[b] I[a]
GL_RGB R[r] G[g] B[b] A
GL_RGBA R[r] G[g] B[b] A[a]
─────────────────────────────────────────────────────
When GL_COLOR_TABLE is enabled, the colors resulting from the pixel map
operation (if it is enabled) are mapped by the color lookup table before
being passed to the convolution operation. The colors resulting from the
convolution operation are modified by the post convolution color lookup
table when GL_POST_CONVOLUTION_COLOR_TABLE is enabled. These modified
colors are then sent to the color matrix operation. Finally, if
GL_POST_COLOR_MATRIX_COLOR_TABLE is enabled, the colors resulting from
the color matrix operation are mapped by the post color matrix color
lookup table before being used by the histogram operation.
NOTES
glColorTable is present only if GL_ARB_imaging is returned when
glGetString is called with an argument of GL_EXTENSIONS.
If target is set to GL_COLOR_TABLE, GL_POST_CONVOLUTION_COLOR_TABLE, or
GL_POST_COLOR_MATRIX_COLOR_TABLE, then _param3 must be a power of two or
a GL_INVALID_VALUE error is generated.
ERRORS
GL_INVALID_ENUM is generated if target is not one of the allowable val‐
ues.
GL_INVALID_ENUM is generated if internalforma is not one of the allow‐
able values.
GL_INVALID_VALUE is generated if _param3 is less than zero.
GL_INVALID_ENUM is generated if _param4 is not one of the allowable val‐
ues.
GL_INVALID_ENUM is generated if _param5 is not one of the allowable val‐
ues.
GL_TABLE_TOO_LARGE is generated if the requested color table is too
large to be supported by the implementation, and target is not a
GL_PROXY_* target.
GL_INVALID_OPERATION is generated if glColorTable is executed between
the execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
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