Prot Fur Sop

[AA74]

Hi all!

this morning i started to check out the proto fur SOP for Houdini 8.1;

i found a great resource on side effects forum done by Wolfwood;

i downloaded his file and everything seems clear.

But, when i started creating a different network to simply put fur on a grid

i get a permanent error on the fur sop; i tried to get the same attributes, i copied and pasted the original nodes,

under the same object node, in the same file provided by Wolfwood, and nothing.

Does anybody can help me to figure out what is going on?

Thanks!

Andrea

furball_150_mod.rar

[Jason]

I know that SESI, around 8.1.711 or something, released a new version of the Fur tools which broke some of Wolfwoods earlier examples. Which version are you running? I thought that he updated his examples for the newer version so I'll bet that you just have a mismatch in versions. Download the latest 8.2 and find the latest archive in Wolfwoods thread and try again perhaps?

[jason_slab]

if u remove your scatter1 from the network the fur works, the scatter is creating unmached geomerty

hope that helps

jason

[AA74]

Thanks a lot!

I removed the scatter from the guides network and it works perfectly, interesting!

At the moment I'm running the 8.1.874 version, I still did not try the 8.2 version, i will do it soon :-)

I was also wandering, wath are the "must have" attributes to make fur works?

in the Wolfwood file i can list the following:

for Guides:

. point attributes:

uv

Cd

width

for rest skin geometry:

. point attributes:

N

up

rotation

furdensity

furangle

furkink

furrandomscale

. vertex attributes

uv

. primitive attributes

area

for the clump geometry:

. vertex attributes

uv

clumppercent

. primitive attributes

clumporigin

clumpradius

Are all those attributes all strictly necesserary, and of the same type

(for example, the uv are vertex attributes instead of point attributes)?

then there is a detail attribute common to every branch of the network: varmap.

is this created automatically by Houdini?

Thanks a lot for the help!

Andrea

[GallenWolf]

Hiya!

I remember if you run the proto_install again (in 8.2), try to find the SOP_Fur.inst in the list (if I am not mistaken after you've installed it it appears on a list to the right, so you may need to scroll up to find it) - if you read the readme there is a detailed descripton on what attributes are read by the fur sop.

GW

[AA74]

Thanks a lot!

now I see the meaning of one of the options during the installation process: view the read-me file :-)

Cheers!

Andrea

[AA74]

i found out the read-me file and we can say that the attributes needed are:

for Guides:

-Cd

-width

-> for what I see those are not mandatory for the fur it-self, but fundamentals to render lines

for rest skin geometry:

-furdensity

-furangle

-furkink

-furrandomscale

for the clump geometry:

-clumppercent

-clumporigin

-clumpradius

Thanks!

and see you soon with some furry images :-)

A.

[GallenWolf]

Hi!

Just a note, some of the attributes are vertex attributes (i think the clumping stuff), not point attribs, that used to trip me up. Have fun!

GW

[AA74]

oh yes, you are right!

the clumping attributes in the Wolfwood file are vertex and primitive attributes:

so, for the clump geometry:

. vertex attributes

clumppercent

. primitive attributes

clumporigin

clumpradius

all the other (for rest and guide geometry) seem to be point attributes

Cheers!

Andrea

[AA74]

Hello!

i applied fur on a character I did 3 years ago, and i got these results;

http://www.3dartist.it/wip/jaw_05_A.jpg

http://www.3dartist.it/wip/jaw_05_B.jpg

I used 3 points lights casting Z-depth shadows;

the color of the fur is done in the sop network;

so I just applied a simple lighting model shader, and on the

diffuse, i plugged the color took from the sop network.

But,

when i started lighting, i had some weird problems;

it seems that the shading was exactly at the opposite side of where it should be;

so i just did a simple normal pass, and i got these results:

http://www.3dartist.it/wip/jaw_06_normal_fur.jpg

and i think I have a problem;

the fur seems not to have any normal value;

is it correct? or I should have a different result?

I think I'm missing something

Any suggestion is more than welcome!

Thanks!

Andrea

p.s.: I'm using the proto fur sop for Houdini 8.1

[Wolfwood]

Hello!

i applied fur on a character I did 3 years ago, and i got these results;

http://www.3dartist.it/wip/jaw_05_A.jpg

http://www.3dartist.it/wip/jaw_05_B.jpg

I used 3 points lights casting Z-depth shadows;

the color of the fur is done in the sop network;

so I just applied a simple lighting model shader, and on the

diffuse, i plugged the color took from the sop network.

But,

when i started lighting, i had some weird problems;

it seems that the shading was exactly at the opposite side of where it should be;

so i just did a simple normal pass, and i got these results:

http://www.3dartist.it/wip/jaw_06_normal_fur.jpg

and i think I have a problem;

the fur seems not to have any normal value;

is it correct? or I should have a different result?

Curves are rendered as thin flat planes that are oriented toward camera. Because of this all the normals will be facing the camera which makes it difficult to light when using the standard lighting models. Have a look at the VEX Hair SHOP.

As for your other question, the reason why your normal pass doesn't look too exciting is because N wasn't normalized before the Shift Range VOP.

[AA74]

Great!

thanks a lot

now I see, I tought fur was redered as a geometry during render time;

Now I'll dive into both the hair shader and the hair VOPs node;

I'm doing the first test and it's working fine :-)

Thanks!

Andrea

[Wolfwood]

now I see, I tought fur was redered as a geometry during render time;

The Fur Procedurals spawns tons and tons of curve geometries which are considered to be a "light-weight" geometry primitive. It is possible to attach a orient vector attribute to your curves. Instead of the curve facing the camera it will face in the direction of the orient attribute (in object space).

Left curve has a width of .1, right curve has a width of .1 and a varying orient attribute.

Edited July 2, 2007 by Wolfwood

[AA74]

Hi!

sorry for the delay, busy days!

really interesting and I have some questions :-)

so, the rot attribute you created in your ball scene is the orient one?

I tried to rename it and it orients all the fur guides of the fur;

the orient attribute is a quaternion, so 4 dimensions attribute;

what is the best way to define it?

I saw you used the function matrixtoquad, is it a common workflow or a specific need for that scene?

to do the changing of the orientation in your last images did you set up the orient attribute as a point attribute?

Thanks a lot!

Andrea

p.s.: i fixed the normal pass, yes i did not normalized:-) !

[Wolfwood]

so, the rot attribute you created in your ball scene is the orient one?

I tried to rename it and it orients all the fur guides of the fur;

The rot attribute is independent of the 'orient' one. The rot attribute is a float 4 (quaternion) that I used to rotate the guide hairs to the surface. (The Copy SOP makes use of the 'rot' attribute)

the orient attribute is a quaternion, so 4 dimensions attribute;

what is the best way to define it?

Take a look at this thread, http://www.sidefx.com/index.php?option=com...opic&t=6679

There are two 'orient' attributes in Houdini. The float4 (quaternion) orient attribute is used by the Copy SOP and Instancing. There is also a float3 (vector) version of 'orient' which is used for curve rendering. In the above image I used the vector version.

I saw you used the function matrixtoquad, is it a common workflow or a specific need for that scene?

Using the 'rot' or 'orient' (float4) to rotate objects in conjunction with the Copy SOP is something that I personally like to do. (Using fur doesn't require those attributes.) Some people like to use the 'N' and 'up' vector attributes instead.

to do the changing of the orientation in your last images did you set up the orient attribute as a point attribute?

Thanks a lot!

Setting the 'orient' (vector) attribute works as either point or vertex attribute. However you need to use the latest version of Houdini for it to work. When the Fur Procedural dumps out geometry it automatically converts all Guide hair attributes to vertex attributes. Up until recently mantra only recognized a point version of the orient attribute.

I apolgize for a lack of documentation in the hip file. It was meant more as reference than as a tutorial.

Edited July 3, 2007 by Wolfwood

[AA74]

Hi!

sorry for the delay!

busy days

thanks a lot for all the informations, really clear and useful! i saved the post :-)

reading the other thread, i understood why you used the rot attribute;

looking at the help i did not found it, so I thought it was a substitute of the orient one;

i also finished my first attempt using fur

www.3dartist.it/wip/jaw_comp_02.0169.jpg

www.3dartist.it/wip/jaw_comp_02.mov

i attached and painted (randomly) the fur;

i just rendered out a little sequence (sorry for the animation, i did it 3 years ago, and it sucks )

it was just to render moving fur and see how much it flickers etc..

i used pretty high sampling values (6 6)

thanks for the help

Cheers!

Andrea