## DFdx

Return the partial derivative of an argument with respect to x

### Declaration

`genType dFdx(float x);`

### Parameters

`p`

specifies the expression of which to take the partial derivative.

### Description

Available only in the fragment shader, `dFdx`

return the partial derivative of expression `p`

in `x`

. 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.