GL_SGI_fft
https://www.khronos.org/registry/OpenGL/extensions/SGI/SGI_fft.txt
GL_SGI_fft

	GL_PIXEL_TRANSFORM_OPERATOR_SGI 0x81C4
	GL_CONVOLUTION_SGI 0x81C5
	GL_FFT_1D_SGI 0x81C6
	GL_PIXEL_TRANSFORM_SGI 0x81C7
	GL_MAX_FFT_WIDTH_SGI 0x81C8
	void glGetPixelTransformParameterfvSGI (GLenum target, GLenum pname, GLfloat* params)
	void glGetPixelTransformParameterivSGI (GLenum target, GLenum pname, GLint* params)
	void glPixelTransformParameterfSGI (GLenum target, GLenum pname, GLfloat param)
	void glPixelTransformParameterfvSGI (GLenum target, GLenum pname, const GLfloat* params)
	void glPixelTransformParameteriSGI (GLenum target, GLenum pname, GLint param)
	void glPixelTransformParameterivSGI (GLenum target, GLenum pname, const GLint* params)
	void glPixelTransformSGI (GLenum target)