fglCopyConvolutionFilter1D(3G) OpenGL Reference
NAMEfglCopyConvolutionFilter1D - copy pixels into a one-dimensional
convolution filter
FORTRAN SPECIFICATION
SUBROUTINE fglCopyConvolutionFilter1D( INTEGER*4 target,
INTEGER*4 internalformat,
INTEGER*4 x,
INTEGER*4 y,
INTEGER*4 width )
PARAMETERS
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.
x, y The window space coordinates of the lower-left coordinate
of the pixel array to copy.
width The width of the pixel array to copy.
DESCRIPTIONfglCopyConvolutionFilter1D defines a one-dimensional convolution filter
kernel with pixels from the current GL_READ_BUFFER (rather than from main
memory, as is the case for fglConvolutionFilter1D).
The screen-aligned pixel rectangle with lower-left corner at (x, y),
width width and height 1 is used to define the convolution filter. If
any pixels within this region are outside the window that is associated
with the GL context, the values obtained for those pixels are undefined.
The pixels in the rectangle are processed exactly as if fglReadPixels had
been called with format set to RGBA, but the process stops just before
final conversion. 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 fglConvolutionParameter using the
GL_CONVOLUTION_1D target and the names GL_CONVOLUTION_FILTER_SCALE and
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fglCopyConvolutionFilter1D(3G) OpenGL Reference
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.
Pixel ordering is such that lower x screen coordinates correspond to
lower i filter image coordinates.
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 fglPixelTransfer.
NOTESfglCopyConvolutionFilter1D is present only if GL_ARB_imaging is returned
when fglGetString 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
fglGetConvolutionParameter using target GL_CONVOLUTION_1D and name
GL_MAX_CONVOLUTION_WIDTH.
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fglCopyConvolutionFilter1D(3G) OpenGL Reference
GL_INVALID_OPERATION is generated if fglCopyConvolutionFilter1D is
executed between the execution of fglBegin and the corresponding
execution of fglEnd.
ASSOCIATED GETS
fglGetConvolutionParameter, fglGetConvolutionFilter
SEE ALSO
fglConvolutionFilter1D, fglConvolutionParameter, fglPixelTransfer
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