Agreed, great job.

Any tricks you've learned by using a PTC oriented approach?

I find myself creating another instance of the same shader for each object to adjust the bias and MSA to get a good result on each object, because a good bias that works on smooth objects doesn't work for flat objects with corners.

Hi Jakub

Awesome image!!

Thanks all! :)

cleger wrote:

Agreed, great job.

Any tricks you've learned by using a PTC oriented approach?

I find myself creating another instance of the same shader for each object to adjust the bias and MSA to get a good result on each object, because a good bias that works on smooth objects doesn't work for flat objects with corners.

Well my approach is plain simple (as I'm not a shader writer) so only things I'm changing are global bias and solid angle parameters in PTC GI. I usually go with bias just a little bit higher than a default value. I guess maximum ever was 0.05 for me. Which gives me the best compromise between "white lines" and black artifacts.

Also I tried to avoid using any external shader and use as many Maya nodes as possible. Which resulted in having only one RSL Node in Hypershade - it adds PTC SSS attributes to the Blinn shader. (Now it's a good place to thank you for sharing the PTC sss code on your blog, which I used here :) )

So this is for me the biggest trick I've learned - to be able to add PTC attributes to Maya shaders. It allows me to use layeredTextures and everything else as I'm used to. And it all works well with standard PTC GI implemented in 3delight - using the same ptc files in one pass.

I hope it makes sense.

Jakub.

clojster wrote:

Also I tried to avoid using any external shader and use as many Maya nodes as possible. Which resulted in having only one RSL Node in Hypershade - it adds PTC SSS attributes to the Blinn shader. (Now it's a good place to thank you for sharing the PTC sss code on your blog, which I used here :) )

So this is for me the biggest trick I've learned - to be able to add PTC attributes to Maya shaders. It allows me to use layeredTextures and everything else as I'm used to. And it all works well with standard PTC GI implemented in 3delight - using the same ptc files in one pass.

I hope it makes sense.

Jakub.

Can you elaborate a bit the RSL node bit? I'm really interested! So basically, I add the SSS attribute on the object, assign a blinn to it... and then? When the RSL node comes into play? And what about the actual code?

The image is amazing! Congratulations!

Btw, let me understand one aspect: basically at the end you texture your object using normal maya workflow (including layered textures)  shade the object with blinn and adding SSS "ontop" using the RLS code? (not bothering to texture subdermal and all that stuff, common in characters)

Marco Cattaneo wrote:

Can you elaborate a bit the RSL node bit? I'm really interested! So basically, I add the SSS attribute on the object, assign a blinn to it... and then? When the RSL node comes into play? And what about the actual code?

The image is amazing! Congratulations!

Btw, let me understand one aspect: basically at the end you texture your object using normal maya workflow (including layered textures)  shade the object with blinn and adding SSS "ontop" using the RLS code? (not bothering to texture subdermal and all that stuff, common in characters)

Cameron is right about the thread. There you'll find the code for RSL...

But to elaborate a bit more: You create RSL node, put the code in it and then connect "out color" of any maya shader (I use Blinn for almost anything) into the "mayacolor" of RSL node. Then, connect "ssscolor" of RSL node into "out color" of SurfaceShader. Then assign that SurfaceShader to your geometry.

So basically you do all your material setup on the Blinn shader, connecting all the textures you like into it, set specularity and reflectivity etc. Then RSL node adds SSS contribution to it and sends it together to the surface shader, which now has everything in it (excluding transparency, but you can connect you transparency textures to out transparency of surface shader directly and it works).

About the SSS - this implementation is quite simple one - not doing any subdermal, backscatter etc. But you could look into misss_fast_skin for implementation of such things and rewrite those for this RSL code. In fact, I might do it next time, but for now I'm ok with this simple SSS.


I can't wait what Cameron will come up with (latter post). I think it will be great!

Last edited by clojster (2012-06-10 01:26:33)

Amazing image!

If you want to add more realism (and IMHO):

1- Use velvet shader for underlying surfaces (instead of Blinn) to simulate the small squale "fur" on leaves.
2- Subsurface model in 3Delight (bi-pole) is not quite right to simulate very thin surface such as leaves. It means that in this case the back-side of a green leaf should be much brighter than the front side (about 30%).

-- aghiles

Last edited by aghiles (2012-06-10 09:51:22)

aghiles wrote:

Amazing image!

If you want to add more realism (and IMHO):

1- Use velvet shader for underlying surfaces (instead of Blinn) to simulate the small squale "fur" on leaves.
2- Subsurface model in 3Delight (bi-pole) is not quite right to simulate very thin surface such as leaves. It means that in this case the back-side of a green leaf should be much brighter than the front side (about 30%).

-- aghiles

Thanks aghiles!

1 - well, Maya doesn't have a velvet shader and I wanted to use just standard Maya shaders as it should be best supported and error-proof. There are tricks to simulate velvet on Blinn, but as it is through Incadescence channel, it shines when using with PTC. But I'm using it anyway in a small scale on blossom. I might do it on leaves too.

2 - you are right. Actually I have double sided material on leaves with separate textures for front/back and the back is brighter to simulate this effect. I think I will make it even stronger. Thanks.
(Is there any chance 3Delight will have implementation for such cases? Or what would be the best workaround?)

EDIT: so I tweaked it...

Last edited by clojster (2012-06-10 14:34:08)

Of course. Mind messaging me what error you get? I'm assuming you've downloaded the blinnSpecularity.h file as well?

Other than that, I think I only had a few errors which are to be expected with compiling a PRM shader in 3Delight, and which were simple enough to change.