hi
could someone please write more about wren rop
what does it do excactly and how to modify it?

Hi Arzo. Wren renders the outline of the geometry, so you can use it for an inked outline in cel shading style.

Go to /out and lay down a Wren ROP (i.e. instead of a Mantra ROP). Then render an object with it. Mplay will probably show nothing, as it will be displaying the (black) ink outline on what looks like a black background (but I believe is actually an empty alpha channel).

To see the outline, in the Mplay window click the 4th colour plane icon (i.e. the white one next to Red, Green, Blue). If my memory serves me, that will provide a white background to contrast with your ink outline.

For a more permanent (and perhaps reliable) answer you set up a compositing network and just overlay the wren layer onto a colour layer.

hi thanks for reply
i can render with it
i would love to modify it to look more hand drawn though

I understand it to be a legacy thing, having seen it in Houdini since H5 at least. Probably designed for technical drawing type work, not cel shading

ah thats it then
it is fast and ok but for some more elaborate npr stuff its too strict
i got some toon shaders on odforce and they are quite nice

Don´t forget that you can vary the line width by altering the number with the “Render Command” from 1.5 to whatever you like. The more the thicker the linestyle will be.

Lutze

thanks lu tze
i want to add some noise to it like a dry brush

Wren can't do that (brush-style rendering).
One nice thing it can do, however, is to output vector EPS files (which you can then bring into Flash, for example).

Dragos

Have you done this recently? Anything special you need to do? I get errors (in Inkscape) when trying to open an EPS whether i render it through Wren or save it as geo from sops.
S'pose I'll give Illustrator a shot when i get home.

Another good thing that it has attribute “linewidth” which you can use in SOPs. So you can actually vary width of the line with depth or any other ways you want.

tjeeds
Have you done this recently? Anything special you need to do? I get errors (in Inkscape) when trying to open an EPS whether i render it through Wren or save it as geo from sops.
S'pose I'll give Illustrator a shot when i get home.

You need to click the small icon to the right of the render command field and there you activate PostScript and tweak the options.
It's not actually eps but ps (postscript) that gets output. It opens fine in Illustrator.

Dragos

Opening them in illustrator sounds fun, then you could apply a brush to the vectors.
That'd be easier than rendering an op_id pass then creating mattes for all the layers then auto rotoscoping them.
If your animating them they'll probably move all over the place though , more like scratch film, alternatively you could add a brush texture to polygon lines by giving them width and rendering them in mantra.

Digitallysane did you mean adding a post script paramater in the wren renderer? I can't seem to find anything under wren or postscript in the edit parameters interface?
cheers
john

This is where you find the parameters:

thanks for that digitallysane
that's really helpful
john