GLSEPARABLEFILTER2D

NAME

C SPECIFICATION

                            GLenum internalformat,
                            GLsizei width,
                            GLsizei height,
                            GLenum format,
                            GLenum type,
                            const GLvoid *row,
                            const GLvoid *column )

PARAMETERS

target

Must be GL_SEPARABLE_2D.

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.

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 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_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, 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.

DESCRIPTION

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 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:

The red, green, blue, alpha, luminance, and/or intensity components of the resulting pixels are stored in floating-point rather than integer 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.  

NOTES

ERRORS

ASSOCIATED GETS

SEE ALSO