about "du,dv" in houdini!

[zbhoudini]

there are parameters "du,dv" to represent an estimate of the amount that the surface parameter u ,v change from sample to sample.for example:

#define MINFILTERWIDTH  1e-7
#define MINDERIV        0.0003    /* sqrt(MINFILTERWIDTH) */

#define filterwidth(x) (max(abs(Du(x) * (du)) + (Dv(x) * (dv)),MINFILTERWIDTH))

;are there some parameters like that to substitute for "du,dv" in houdini?

[SpencerL]

there are parameters "du,dv" to represent an estimate of the amount that the surface parameter u ,v change from sample to sample.for example:

#define MINFILTERWIDTH  1e-7
#define MINDERIV        0.0003    /* sqrt(MINFILTERWIDTH) */

#define filterwidth(x) (max(abs(Du(x) * (du)) + (Dv(x) * (dv)),MINFILTERWIDTH))

;are there some parameters like that to substitute for "du,dv" in houdini?

check out the "primduv" expression

[Mario Marengo]

Have a look at this wiki page. Following the mappings in that table, your RSL fragment would become:

#define filterwidth(x) (max(abs(Du(x)) + abs(Dv(x)),MINFILTERWIDTH))

BTW, note that I added another abs() to your expression as it wouldn't make much sense otherwise... perhaps a typo when copy-pasting?

Cheers.

[zbhoudini]

thank you very much!