MirOS Manual: glCopyConvolutionFilter1D(3)


GLCOPYCONVOLUTIONFILTUNIX(ProgrammerGLCOPYCONVOLUTIONFILTER1D(3G)

NAME

     glCopyConvolutionFilter1D - copy pixels into a one-
     dimensional convolution filter

C SPECIFICATION

     void glCopyConvolutionFilter1D( GLenum target,
                                     GLenum internalformat,
                                     GLint x,
                                     GLint y,
                                     GLsizei width )

PARAMETERS

     target          Must be GL_CONVOLUTION_1D.

     internalformat  The internal  of the convolution filter ker-
                     nel. 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.

DESCRIPTION

     glCopyConvolutionFilter1D defines a one-dimensional convolu-
     tion filter kernel with pixels from the current
     GL_READ_BUFFER (rather than from main memory, as is the case
     for glConvolutionFilter1D).

     The screen-aligned pixel rectangle with lower-left corner at
     (x, y), width width and height 1 is used to define the con-
     volution filter.  If any pixels within this region are out-
     side 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
     glReadPixels had been called with format set to RGBA, but

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GLCOPYCONVOLUTIONFILTUNIX(ProgrammerGLCOPYCONVOLUTIONFILTER1D(3G)

     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 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

     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 glPixelTransfer.

NOTES

     glCopyConvolutionFilter1D 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.

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GLCOPYCONVOLUTIONFILTUNIX(ProgrammerGLCOPYCONVOLUTIONFILTER1D(3G)

     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_OPERATION is generated if
     glCopyConvolutionFilter1D is executed between the execution
     of glBegin and the corresponding execution of glEnd.

ASSOCIATED GETS

     glGetConvolutionParameter, glGetConvolutionFilter

SEE ALSO

     glConvolutionFilter1D(3G), glConvolutionParameter(3G),
     glPixelTransfer(3G)

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