xnoised

void  xnoised(float x, float &v, float &dvdx)

void  xnoised(float x, vector &v, vector &dvdx)

void  xnoised(float x, float y, float &v, float &dvdx, float &dvdy)

void  xnoised(float x, float y, vector &v, vector &dvdx, vector &dvdy)

void  xnoised(vector xyz, float &v, float &dvdx, float &dvdy, float &dvdz)

void  xnoised(vector xyz, vector &v, vector &dvdx, vector &dvdy, vector &dvdz)

void  xnoised(vector4 xyzw, float &v, float &dvdx, float &dvdy, float &dvdz, float &dvdw)

void  xnoised(vector4 xyzw, vector &v, vector &dvdx, vector &dvdy, vector &dvdz, vector &dvdw)

This computes both the simplex noise value, and the derivatives of the noise along each axis. This can be performed quite efficiently as there are analytic derivatives available.

See noise and randomness in the VEX language guide for more information.