On 19 jan, 09:52, Bo Schwarzstein <bo.sc...@...> wrote:

Hello folks,

In specification, it sais "Arbitrary derivatives without grids or
extra shading points.", but I really confused how it works without
explicit grid. Does it like the GPU, compute the derivatives on screen
space ?

No, it does automatic differentiation.

The overall idea is that if your inputs know their derivatives ( for
instance, when raytracing a primitive, computing P, dP/dx and dP/dy is
easy )
and your shading library know how to differentiate all its operators,
you are able to maintain derivatives quantities while shading.

Look at http://jgt.akpeters.com/papers/Piponi04/ for a complete
reference.


Hopes this helps

Henri

Thanks.