glSeparableFilter2D(3G) OpenGL Reference glSeparableFilter2D(3G)
glSeparableFilter2D - define a separable two-dimensional convolution
filter
void glSeparableFilter2D( GLenum target,
GLenum internalformat,
GLsizei width,
GLsizei height,
GLenum format,
GLenum type,
const GLvoid *row,
const GLvoid *column )
target Must be GL_SEPARABLE_2D.
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 number of elements in the pixel array referenced by
row. (This is the width of the separable filter kernel.)
height The number of elements in the pixel array referenced by
column. (This is the height of the separable filter
kernel.)
format The format of the pixel data in row and column. The
allowable values are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA,
GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_ABGR_EXT,
GL_INTENSITY, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
type The type of the pixel data in row and column. 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,
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glSeparableFilter2D(3G) OpenGL Reference glSeparableFilter2D(3G)
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.
row Pointer to a one-dimensional array of pixel data that is
processed to build the row filter kernel.
column Pointer to a one-dimensional array of pixel data that is
processed to build the column filter kernel.
glSeparableFilter2D builds a two-dimensional separable convolution filter
kernel from two arrays of pixels.
The pixel arrays specified by (width, format, type, row) and (height,
format, type, column) are processed just as if they had been passed to
glDrawPixels, but processing stops after the final expansion to RGBA is
completed.
Next, the R, G, B, and A components of all pixels in both arrays are
scaled by the four separable 2D GL_CONVOLUTION_FILTER_SCALE parameters
and biased by the four separable 2D GL_CONVOLUTION_FILTER_BIAS
parameters. (The scale and bias parameters are set by
glConvolutionParameter using the GL_SEPARABLE_2D 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:
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glSeparableFilter2D(3G) OpenGL Reference glSeparableFilter2D(3G)
________________________________________________________________________
Internal Format Red Green Blue Alpha Luminance Intensity
_______________________________________________________________________
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 two one-dimensional filter kernel images. The row
image is indexed by coordinate i starting at zero and increasing from
left to right. Each location in the row image is derived from element i
of row. The column image is indexed by coordinate j starting at zero and
increasing from bottom to top. Each location in the column image is
derived from element j of column.
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.
glSeparableFilter2D is present only if GL_ARB_imaging is returned when
glGetString is called with an argument of GL_EXTENSIONS.
GL_ABGR_EXT is valid only if the EXT_abgr extension is supported.
GL_INVALID_ENUM is generated if target is not GL_SEPARABLE_2D.
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_SEPARABLE_2D and name
GL_MAX_CONVOLUTION_WIDTH.
GL_INVALID_VALUE is generated if height is less than zero or greater than
the maximum supported value. This value may be queried with
glGetConvolutionParameter using target GL_SEPARABLE_2D and name
GL_MAX_CONVOLUTION_HEIGHT.
GL_INVALID_ENUM is generated if format is not one of the allowable
values.
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glSeparableFilter2D(3G) OpenGL Reference glSeparableFilter2D(3G)
GL_INVALID_ENUM is generated if type is not one of the allowable values.
GL_INVALID_OPERATION is generated if glSeparableFilter2D is executed
between the execution of glBegin and the corresponding execution of
glEnd.
GL_INVALID_OPERATION is generated if height 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 format is not
GL_RGB.
GL_INVALID_OPERATION is generated if height 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 format
is not GL_RGBA, GL_BGRA or GL_ABGR_EXT.
glGetConvolutionParameter, glGetSeparableFilter
glConvolutionFilter1D, glConvolutionFilter2D, glConvolutionParameter,
glPixelTransfer
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