The Book of Shaders by Patricio Gonzalez Vivo


Return the partial derivative of an argument with respect to x


genType dFdx(float x);


p specifies the expression of which to take the partial derivative.


Available only in the fragment shader, dFdx return the partial derivative of expression p in x. Derivatives 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.

See Also