GLCONVOLUTIONFILTER1D
Section: Misc. Reference Manual Pages (3G)
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NAME
glConvolutionFilter1D
- define a one-dimensional convolution filter
C SPECIFICATION
void glConvolutionFilter1D(
GLenum target,
GLenum internalformat,
GLsizei width,
GLenum format,
GLenum type,
const GLvoid *image )
PARAMETERS
- target
-
Must be GL_CONVOLUTION_1D.
- internalformat
-
The internal of the convolution filter kernel.
The allowable values are
GL_ALPHA,
GL_LUMINANCE,
GL_LUMINANCE_ALPHA,
GL_INTENSITY,
GL_RGB, and
GL_RGBA.
- width
-
The width of the pixel array referenced by image.
- format
-
The of the pixel data in image.
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, or
GL_RGBA16.
- type
-
The type of the pixel data in image.
Symbolic constants
GL_UNSIGNED_BYTE,
GL_BYTE,
GL_BITMAP,
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
are accepted.
- image
-
Pointer to a one-dimensional array of pixel data that is processed to
build the convolution filter kernel.
DESCRIPTION
glConvolutionFilter1D builds a one-dimensional convolution filter kernel from an array of
pixels.
The pixel array specified by width, format, type, and image
is extracted from memory and
processed just as if glDrawPixels were called, but processing
stops after the final expansion to RGBA is completed.
The R, G, B, and A components of each pixel are next scaled by the four
1D GL_CONVOLUTION_FILTER_SCALE parameters and biased by the
four 1D GL_CONVOLUTION_FILTER_BIAS parameters.
(The scale and bias parameters are set by glConvolutionParameter
using the GL_CONVOLUTION_1D target and the names
GL_CONVOLUTION_FILTER_SCALE and GL_CONVOLUTION_FILTER_BIAS.
The parameters themselves are vectors of four values that are applied to red,
green, blue, and alpha, in that order.)
The R, G, B, and A values are not clamped to [0,1] at any time during this
process.
Each pixel is then converted to the internal 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 (red, green, blue,
alpha, luminance, 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 | |
|
|
The red, green, blue, alpha, luminance, and/or intensity components of
the resulting pixels are stored in floating-point rather than integer
They form a one-dimensional filter kernel image indexed with coordinate
i such that i starts at 0 and increases from left to right.
Kernel location i is derived from the ith pixel, counting from 0.
Note that after a convolution is performed, the resulting color
components are also scaled by their corresponding
GL_POST_CONVOLUTION_c_SCALE parameters and biased by their
corresponding GL_POST_CONVOLUTION_c_BIAS parameters (where
c takes on the values RED, GREEN, BLUE, and
ALPHA).
These parameters are set by glPixelTransfer.
NOTES
glConvolutionFilter1D is present only if GL_ARB_imaging is returned when glGetString
is called with an argument of GL_EXTENSIONS.
ERRORS
GL_INVALID_ENUM is generated if target is not
GL_CONVOLUTION_1D.
GL_INVALID_ENUM is generated if internalformat is not one of the
allowable values.
GL_INVALID_VALUE is generated if width is less than zero or greater
than the maximum supported value.
This value may be queried with glGetConvolutionParameter
using target GL_CONVOLUTION_1D and name
GL_MAX_CONVOLUTION_WIDTH.
GL_INVALID_ENUM is generated if format is not one of the allowable
values.
GL_INVALID_ENUM is generated if type is not one of the allowable
values.
GL_INVALID_OPERATION is generated if glConvolutionFilter1D is executed
between the execution of glBegin and the corresponding
execution of glEnd.
GL_INVALID_OPERATION is generated if format is one of
GL_UNSIGNED_BYTE_3_3_2,
GL_UNSIGNED_BYTE_2_3_3_REV,
GL_UNSIGNED_SHORT_5_6_5, or
GL_UNSIGNED_SHORT_5_6_5_REV
and type is not GL_RGB.
GL_INVALID_OPERATION is generated if format is one of
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, or
GL_UNSIGNED_INT_2_10_10_10_REV
and type is neither GL_RGBA nor GL_BGRA.
ASSOCIATED GETS
glGetConvolutionParameter, glGetConvolutionFilter
SEE ALSO
glConvolutionFilter2D(3G),
glSeparableFilter2D(3G),
glConvolutionParameter(3G),
glPixelTransfer(3G)