In my toying around with pixel-wise depth-of-field blur, I am

encountering a need for pixel jitter. I want to run

vwrays -fd -vf tempvf -x 740 -y 480 | rcalc -id6

-e `vwright i < tempvf`

[expressions to modify $1..$6, the ray origin and direction]

-od | rtrace -fdc -x 740 -y 480 @opts scene.oct > img.pic

but there is no facility to incorporate pixel jitter, as defined

in rpict(1), save the use of the variables returned by vwright:

## ···

------------

Nt: view type ('v'==1,'l'==2,'a'==3,'h'==4,'c'==5)

Npx: view point x value

Npy: view point y value

Npz: view point z value

Ndx: view direction x value (normalized)

Ndy: view direction y value (normalized)

Ndz: view direction z value (normalized)

Nux: view up vector x value (normalized)

Nuy: view up vector y value (normalized)

Nuz: view up vector z value (normalized)

Nh: view horizontal size

Nv: view vertical size

Ns: view shift

Nl: view lift

No: view fore clipping distance

Na: view aft clipping distance

Nhx: derived horizontal image vector x value (normalized)

Nhy: derived horizontal image vector y value (normalized)

Nhz: derived horizontal image vector z value (normalized)

Nhn: derived horizontal image vector multiplier

Nvx: derived vertical image vector x value (normalized)

Nvy: derived vertical image vector y value (normalized)

Nvz: derived vertical image vector z value (normalized)

Nvn: derived vertical image vector multiplier

------------

My question is: how do I use these variables to incorporate pixel

jitter into these renderings? I do not know how to scale the

Nhx,Nhy,Nhz and Nvx,Nvy,Nvz vectors to jitter over one pixel's

width. Do I multiply by Nh,Nv and divide by 740 and 480,

respectively? Or does it depend on the view type?

Mark