1GLCONVOLUTIONPARAMET(3G) OpenGL Manual GLCONVOLUTIONPARAMET(3G)
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6 glConvolutionParameter - set convolution parameters
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9 void glConvolutionParameterf(GLenum target, GLenum pname,
10 GLfloat params);
11 void glConvolutionParameteri(GLenum target, GLenum pname,
13 GLint params);
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16 target
17 The target for the convolution parameter. Must be one of
18 GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, or GL_SEPARABLE_2D.
19 pname
21 The parameter to be set. Must be GL_CONVOLUTION_BORDER_MODE.
22 params
24 The parameter value. Must be one of GL_REDUCE, GL_CONSTANT_BORDER,
25 GL_REPLICATE_BORDER.
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29 void glConvolutionParameterfv(GLenum target, GLenum pname,
30 const GLfloat * params);
31 void glConvolutionParameteriv(GLenum target, GLenum pname,
33 const GLint * params);
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36 target
37 The target for the convolution parameter. Must be one of
38 GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, or GL_SEPARABLE_2D.
39 pname
41 The parameter to be set. Must be one of GL_CONVOLUTION_BORDER_MODE,
42 GL_CONVOLUTION_BORDER_COLOR, GL_CONVOLUTION_FILTER_SCALE, or
43 GL_CONVOLUTION_FILTER_BIAS.
44 params
46 The parameter value. If pnamev is GL_CONVOLUTION_BORDER_MODE,
47 paramsv must be one of GL_REDUCE, GL_CONSTANT_BORDER, or
48 GL_REPLICATE_BORDER. Otherwise, must be a vector of four values
49 (for red, green, blue, and alpha, respectively) to be used for
50 scaling (when pnamev is GL_CONVOLUTION_FILTER_SCALE), or biasing
51 (when pnamev is GL_CONVOLUTION_FILTER_BIAS) a convolution filter
52 kernel or setting the constant border color (when pnamev is
53 GL_CONVOLUTION_BORDER_COLOR.
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56 glConvolutionParameter sets the value of a convolution parameter.
57 target selects the convolution filter to be affected:
59 GL_CONVOLUTION_1D, GL_CONVOLUTION_2D, or GL_SEPARABLE_2D for the 1D,
60 2D, or separable 2D filter, respectively.
61 pname selects the parameter to be changed. GL_CONVOLUTION_FILTER_SCALE
63 and GL_CONVOLUTION_FILTER_BIAS affect the definition of the convolution
64 filter kernel; see glConvolutionFilter1D(), glConvolutionFilter2D(),
65 and glSeparableFilter2D() for details. In these cases, paramsv is an
66 array of four values to be applied to red, green, blue, and alpha
67 values, respectively. The initial value for GL_CONVOLUTION_FILTER_SCALE
68 is (1, 1, 1, 1), and the initial value for GL_CONVOLUTION_FILTER_BIAS
69 is (0, 0, 0, 0).
70 A pname value of GL_CONVOLUTION_BORDER_MODE controls the convolution
72 border mode. The accepted modes are:
73 GL_REDUCE
75 The image resulting from convolution is smaller than the source
76 image. If the filter width is Wf and height is Hf, and the source
77 image width is Ws and height is Hs, then the convolved image width
78 will be Ws - Wf + 1 and height will be Hs - Hf + 1. (If this
79 reduction would generate an image with zero or negative width
80 and/or height, the output is simply null, with no error generated.)
81 The coordinates of the image resulting from convolution are zero
82 through Ws - Wf in width and zero through Hs - Hf in height.
83 GL_CONSTANT_BORDER
85 The image resulting from convolution is the same size as the source
86 image, and processed as if the source image were surrounded by
87 pixels with their color specified by the
88 GL_CONVOLUTION_BORDER_COLOR.
89 GL_REPLICATE_BORDER
91 The image resulting from convolution is the same size as the source
92 image, and processed as if the outermost pixel on the border of the
93 source image were replicated.
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96 glConvolutionParameter is present only if ARB_imaging is returned when
97 glGetString() is called with an argument of GL_EXTENSIONS.
98 In cases where errors can result from the specification of invalid
100 image dimensions, it is the dimensions after convolution that are
101 tested, not the dimensions of the source image. For example,
102 glTexImage1D() requires power-of-two image size. When GL_REDUCE border
103 mode is in effect, the source image must be larger than the final
104 power-of-two size by one less than the size of the 1D filter kernel.
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107 GL_INVALID_ENUM is generated if target is not one of the allowable
108 values.
109 GL_INVALID_ENUM is generated if pname is not one of the allowable
111 values.
112 GL_INVALID_ENUM is generated if pname is GL_CONVOLUTION_BORDER_MODE and
114 params is not one of GL_REDUCE, GL_CONSTANT_BORDER, or
115 GL_REPLICATE_BORDER.
116 GL_INVALID_OPERATION is generated if glConvolutionParameter is executed
118 between the execution of glBegin() and the corresponding execution of
119 glEnd().
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122 glGetConvolutionParameter()
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125 glConvolutionFilter1D(), glConvolutionFilter2D(),
126 glSeparableFilter2D(), glGetConvolutionParameter()
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129 Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed
130 under the SGI Free Software B License. For details, see
131 http://oss.sgi.com/projects/FreeB/.
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134 opengl.org
135opengl.org 06/10/2014 GLCONVOLUTIONPARAMET(3G)