dFdx, dFdy - OpenGL ES 3 Reference Pages

## Name

dFdx, dFdy — return the partial derivative of an argument with respect to x or y

## Declaration

`genType dFdx(` | genType p`)`;

`genType dFdy(` | genType p`)`;

## Parameters

`p`

  Specifies the expression of which to take the partial derivative.

## Description

Available only in the fragment shader, `dFdx` and `dFdy` return the partial derivative of expression `p` in x and y, respectively. Deviatives are calculated using local differencing. Expressions that imply higher order derivatives such as `dFdx(dFdx(n))` have undefined results, as do mixed-order derivatives such as `dFdx(dFdy(n))`. It is assumed that the expression `p` is continuous and therefore, expressions evaluated via non-uniform control flow may be undefined.

## Version Support

| OpenGL ES Shading Language Version
--- | ---
Function Name | 1.00 | 3.00
dFdx | - | ✔
dFdy | - | ✔

## See Also

fwidth

## 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. http://opencontent.org/openpub/.