GLGETCONVOLUTIONPARAMETEREXT(3GL)GLGETCONVOLUTIONPARAMETEREXT(3GL)NAME
glGetConvolutionParameterEXT - get convolution parameters
C SPECIFICATION
void glGetConvolutionParameterivEXT ( GLenum target,
GLenum pname,
GLint* params)
void glGetConvolutionParameterfvEXT ( GLenum target,
GLenum pname,
GLint* params)
PARAMETERS
target The target Convolution filter. Must be GL_CONVOLUTION_1D_EXT,
GL_CONVOLUTION_2D_EXT or GL_SEPARABLE_2D_EXT.
pname The Symbolic names of various convolution parameters. Must be
one of GL_CONVOLUTION_FILTER_SCALE_EXT, GL_CONVOLUTION_FIL‐
TER_BIAS_EXT, GL_CONVOLUTION_BORDER_MODE_EXT, GL_CONVOLU‐
TION_FORMAT_EXT, GL_CONVOLUTION_WIDTH_EXT, GL_CONVOLU‐
TION_HEIGHT_EXT, GL_MAX_CONVOLUTION_WIDTH_EXT, GL_MAX_CONVOLU‐
TION_HEIGHT_EXT, or GL_CONVOLUTION_BORDER_COLOR_HP.
params A pointer to an array where the values of the parameters are
stored.
DESCRIPTION
glGetConvolutionParameterEXT is part of the GL_EXT_convolution exten‐
sion, which adds convolution to the pixel transfer path.
When pname is set to GL_CONVOLUTION_FILTER_SCALE_EXT, GL_CONVOLU‐
TION_FILTER_BIAS_EXT, or GL_CONVOLUTION_BORDER_COLOR_HP, glGetConvolu‐
tionParameterEXT returns the convolution filter image scale, bias or
border color parameters for the image specified by target. <params>
point to an array of four elements, which receive the scale, bias and
border colors respectively for red, green, blue, and alpha, in that
order.
glGetConvolutionParameterEXT can also be used to retrieve the border
mode, format, width, height, maximum width or maximum height of a con‐
volution filter image. For these pname needs to be set to GL_CONVOLU‐
TION_BORDER_MODE_EXT, GL_CONVOLUTION_FORMAT_EXT, GL_CONVOLU‐
TION_WIDTH_EXT, GL_CONVOLUTION_HEIGHT_EXT, GL_MAX_CONVOLU‐
TION_WIDTH_EXT, or GL_MAX_CONVOLUTION_HEIGHT_EXT. A single value will
be returned in the params array.
The following table lists the format, border mode, width, and height
parameters that may be queried. For each symbolic constant listed below
for pname, params must point to an array of the given length, and
receive the values indicated.
┌────────────────────────────────────────────────────────────────────────────┐
│ pname N Meaning │
├────────────────────────────────────────────────────────────────────────────┤
│GL_CONVOLUTION_FORMAT_EXT 1 Internal format (e.g. GL_RGBA) │
│GL_CONVOLUTION_BORDER_MODE_EXT 1 Border mode (e.g GL_IGNORE_BORDER_HP) │
│GL_CONVOLUTION_WIDTH_EXT 1 Width of filter image │
│GL_CONVOLUTION_HEIGHT_EXT 1 Height of filter image │
│GL_MAX_CONVOLUTION_WIDTH_EXT 1 Maximum allowed width of filter image │
│GL_MAX_CONVOLUTION_HEIGHT_EXT 1 Maximum allowed height of filter image │
└────────────────────────────────────────────────────────────────────────────┘
ERRORS
GL_INVALID_ENUM is generated if target is not one of the acceptable
values.
GL_INVALID_ENUM is generated if pname is not one of the acceptable val‐
ues.
SEE ALSO
glGetConvolutionFilterEXT, glGetSeparableFilterEXT, glConvolutionFil‐
ter1DEXT, glConvolutionFilter2DEXT, glSeparableFilter2DEXT, glCopyCon‐
volutionFilter1DEXT, glCopyConvolutionFilter2DEXT, glConvolutionParame‐
teriEXT, glConvolutionParameterivEXT, glConvolutionParameterfEXT,
glConvolutionParameterfvEXT, glTexImage1D, glGetTexImage, glDrawPixels,
glCopyPixels, glReadPixels, glTexImage2D, glTexSubImage2DEXT, glCopy‐
TexImage2DEXT, glCopyTexSubImage2DEXT, glGetTexImage, glEnable, glDis‐
able, glIsEnabled.
1 Dec 97 GLGETCONVOLUTIONPARAMETEREXT(3GL)