From OpenGL Reference
Jump to navigation Jump to search

Return the sum of the absolute value of derivatives in x and y.


genType fwidth( genType p );
genType fwidthCoarse( genType p );
genType fwidthFine( genType p );


p - Specifies the expression of which to take the partial derivative.


Available only in the fragment shader, these functions return the sum of the absolute derivatives in [math]x[/math] and [math]y[/math] using local differencing for the input argument p . fwidth is equivalent to abs (dFdx(p)) + abs (dFdy(p)). fwidthCoarse is equivalent to abs (dFdxCoarse(p)) + abs (dFdyCoarse(p)). fwidthFine is equivalent to abs (dFdxFine(p)) + abs (dFdyFine(p)).

Version Support[edit]

fwidth 1.1+
fwidthCoarse, fwidthFine 4.5+

See Also[edit]



Copyright© 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.