PDA

View Full Version : Fresnel like effect controlled by ramps.


RichSuchy
04-10-2003, 07:04 PM
I want to control difuse and even color variations of specular based on facing ratio so that one end of a ramp relates to one and the other end relates to zero... in other words I want my ramp assigned to the faceing ratio returned value...
How do I set that up.

I used to do thyis in lightwave but Im a little confused about how to go about it in Maya... do I require layered shaders or does that needlessly complicate the issue?

Rich

stunndman
04-11-2003, 05:07 AM
use a sampler info node

connect it's "Facing Ratio" to the "Uv Coord->V Coord" attribute of a ramp node (if it is a V Ramp type ramp)

that's it - now you can set up the colors of your ramp to your liking - facing ratio will be 1 if you are facing the surface head-on

RichSuchy
04-11-2003, 05:15 AM
Thank you for pointing out what should have been obvious. Im a little embarassed i was unable to figure it out.

Now life is good.

Rich


Originally posted by stunndman
use a sampler info node

connect it's "Facing Ratio" to the "Uv Coord->V Coord" attribute of a ramp node (if it is a V Ramp type ramp)

that's it - now you can set up the colors of your ramp to your liking - facing ratio will be 1 if you are facing the surface head-on

Stahlberg
04-12-2003, 03:47 AM
Hm, I don't know if that's so obvious... this is one of the many little things that bug me about the Maya renderer... this effect should be a single node or parameter somewhere, called Falloff, when you turn it on you access the ramp. A 'mappable' button to add some texture on top of it. Intuitive and quick, yet not sacrificing any flexibility. (Because you could still have the utility nodes for those who like to spend weeks testing different networks.)

edit: yes I know I can just make MEL buttons for this, and perhaps many other things I find are missing, but not for all... and the fun of making your own buttons with your own icons, and searching and installing free scripts, qiuckly grows old. Especially at version-change time, or 're-install' time...

CIM
04-12-2003, 04:55 AM
Rich, you really need to move from Geocities.

yohan
04-12-2003, 12:21 PM
There is this node called clearCoat that has the same effect. But even though it might take a few extra clicks using the sampler info>ramp technique, i don't think many people care about that node. I know i don't ;)

stunndman
04-12-2003, 12:46 PM
Originally posted by Stahlberg
Hm, I don't know if that's so obvious... this is one of the many little things that bug me about the Maya renderer... this effect should be a single node or parameter somewhere, called Falloff, when you turn it on you access the ramp. A 'mappable' button to add some texture on top of it. Intuitive and quick, yet not sacrificing any flexibility. (Because you could still have the utility nodes for those who like to spend weeks testing different networks.)


but they would have to make this for diffuse, transparency, reflectivity, ... - this would be quite some overhead for the interface - having all this checkboxes and remap buttons

i'm not sure if this would be any good

jeremybirn
04-13-2003, 05:05 PM
Originally posted by Stahlberg
this effect should be a single node or parameter somewhere, called Falloff, when you turn it on you access the ramp. A 'mappable' button to add some texture on top of it. Intuitive and quick, yet not sacrificing any flexibility. (Because you could still have the utility nodes for those who like to spend weeks testing different networks.)

The "ramp shader" (added in Maya 4.5) includes editable gradients on a lot of parameters. You can add points and edit the graph on a reflectivity gradient and simulate the fresnel effect all within that 1 node, or edit a color gradient based on a center to edge tansition or other dependencies. It certainly doesn't replace everything that you could build in hypershade, but it does give more convenient access to a lot of effects.

-jeremy

Stahlberg
04-14-2003, 06:35 AM
Sounds good, I should get 4.5

RichSuchy
04-14-2003, 09:09 PM
OK...


It isnt as straight forward as I thought. Something is NOT working with the ramps and facing ratio.

It looks correct on the little preview balls but It seems that when I use layered shaders and blend in anything at all I get strange sharp edged and random appearing results on my uv mapped objects. What am I missing? Im sure some of you have had similar results when trying to use this.

What im trying to do is blend a little color shift accross a womans face... yellow in the faceing, through red across the meat of the model, and blue in the glancing angle... again all very subtle. Im getting random globs of color, that have little to do with the faceing angle.

:hmm:

CGTalk Moderation
01-14-2006, 08:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.