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# docs.GL

GLSL 4
GLSL ES 3

# fwidth

## Name

fwidth — return the sum of the absolute derivatives in x and y

## Declaration

`genType fwidth(` | genType p`)`;

## Parameters

`p`

  Specifies the expression of which to take the partial derivative.

## Description

Available only in the fragment shader, `fwidth` returns the sum of the absolute derivatives in x and y using local differencing for the input argument `p`. It is equivalent to `abs(dFdx(p)) + abs(dFdy(p))`.

## Version Support

| OpenGL ES Shading Language Version
--- | ---
Function Name | 1.00 | 3.00 | 3.10
fwidth | - | ✔ | ✔

## See Also

abs, dFdx, dFdy

## Copyright

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. https://opencontent.org/openpub/.

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