glCopyConvolutionFilter1D man page on OpenBSD

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GLCOPYCONVOLUTIONFILTER1D(3G)			 GLCOPYCONVOLUTIONFILTER1D(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 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.

DESCRIPTION
       glCopyConvolutionFilter1D 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 glConvolutionFilter1D).

       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 glReadPixels
       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 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.

       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)

								 March 1, 2011
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