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 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 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 FormatRedGreenBlueAlphaLuminanceIntensityGL_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 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 takes on the values RED, GREEN, BLUE, and ALPHA ). These parameters are set by glPixelTransfer.
glCopyConvolutionFilter1D is present only if ARB_imaging is returned when glGetString is called with an argument of GL_EXTENSIONS.
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glCopyConvolutionFilter1D: man2/glCopyConvolutionFilter1D.xml
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 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 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 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 takes on the values RED, GREEN, BLUE, and ALPHA ). These parameters are set by glPixelTransfer.
glCopyConvolutionFilter1D is present only if ARB_imaging is returned when glGetString is called with an argument of GL_EXTENSIONS.