glConvolutionFilter1D — define a one-dimensional convolution filter
void glConvolutionFilter1D( | GLenum | target, |
| GLenum | internalformat, | |
| GLsizei | width, | |
| GLenum | format, | |
| GLenum | type, | |
| const GLvoid * | data); |
target
Must be GL_CONVOLUTION_1D.
internalformat
The internal format of the convolution filter kernel.
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.
width
The width of the pixel array referenced by data.
format
The format of the pixel data in data.
The allowable values are
GL_ALPHA,
GL_LUMINANCE,
GL_LUMINANCE_ALPHA,
GL_INTENSITY,
GL_RGB, and
GL_RGBA.
type
The type of the pixel data in data.
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.
dataPointer to a one-dimensional array of pixel data that is processed to build the convolution filter kernel.
glConvolutionFilter1D builds a one-dimensional convolution filter kernel from an array of
pixels.
The pixel array specified by width, format, type, and data
is extracted from memory and
processed just as if glDrawPixels were called, but processing
stops after the final expansion to RGBA is completed.
If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target
(see glBindBuffer) while a convolution filter is
specified, data is treated as a byte offset into the buffer object's data store.
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 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 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 format. 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.
glConvolutionFilter1D is present only if ARB_imaging is returned when glGetString
is called with an argument of GL_EXTENSIONS.
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_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_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_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.
GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and the buffer object's data store is currently mapped.
GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and the data would be unpacked from the buffer
object such that the memory reads required would exceed the data store size.
GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
GL_PIXEL_UNPACK_BUFFER target and data is not evenly divisible
into the number of bytes needed to store in memory a datum indicated by type.
GL_INVALID_OPERATION is generated if glConvolutionFilter1D is executed
between the execution of glBegin and the corresponding
execution of glEnd.
glGetConvolutionParameter, glGetConvolutionFilter
glGet with argument GL_PIXEL_UNPACK_BUFFER_BINDING
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