Opal Shader Need Help

[chris-giusti]

Alright, I made some blinn's to replicate how opal produces exquisite colours, and these are in specific not-physically possible shades (over a value of 1 for some features anyways). Then I made some nCloth and a shrinking sphere to crumple a piece of geometry so that it would reflect at different angles, and that came out nice with the shaders applied but the mesh was so complicated and still flat and some parts still look 'too sharp' I suppose. The problem is that it was many meshes of the same mesh though, but if I make a single mesh, how could I mix a shader so that each blinn appears smoothly throughout the mesh instead of assigning to faces? The blinns do not have the same specular rolloff, eccentricity or other values.

[joojaa]

how could I mix a shader so that each blinn appears smoothly throughout the mesh instead of assigning to faces?

Im trtying to imagine what fundamental misunderstanding you have. You dont need to mix the shaders. Each time a shader is calculated in the scene its a separate entity, thus each point in ONE blinn shader can havce different values for ANY attrubute. All you have to do is connect some phycially plausible fuction as input the the slots. This is called texturing and it does not have to be based on just position and just drive color it can affect anythhing.

Now the real problem is what kind of fundamental thinking block are you missing, so i would know where to start.

[chris-giusti]

Okay.. well.. you are not helping..

There are 4 blinns, with different specular roll off etc. because for each, when lit, produce color differently.

I would like to know how I can get a mesh to have 4 blinns on it (or more) that are changing from one to the other, and not assigned to faces.. but somehow mixed.

And I have said before, I am not the greatest with shaders or texturing at all.. that is why I am asking, I AM clueless. Thanks for rubbing it in.

Any help would be great so long as it's helpful.. 

Basically I would like to paint 1 blinn in one area and another blinn in another area on a mesh. 

[joojaa]

Okay.. well.. you are not helping..

You know its the kind of situation where no matter what i would say you wouldn't be helped by any initial answer. I can only ever anybody they are  wrong or thinking upside down, every person needs to realize and work thsi out for themselves. Now you came back so your saying that your willing to work out your world view. Theres nothing i can do to people who dont have this capacity.

I would like to know how I can get a mesh to have 4 blinns on it (or more) that are changing from one to the other

Yes, but you dont want to do that, you dont need 4 blinns one is enough. The only reason you would want to have different shaders mix together is if they are not same base -> in other words you want to mix a blinn and a phong for example. If you just have 4- unlimited number of blinns mixing them together is the same thing as having 1 blinn. Theers no difference no difference other than having 4 - unlimited number of separate blinns is slower and uses more memory, harder to control and more convoluted. Just the kind of wrong way of thinking im talking about.

Let me illustrate this:

lets assume you want to do something where you are mixing 2 blinn shaders. Lets for arguments sake say that your mixing pattern is a cheker to keep things simple. Well now each and every sample in the object is a different blinn form ALL the rest, they just inherit the same database. However each point can have any vaue differently:

So lets make each specular color different colored, im doing this in mel so you can just copy paste and look at the result. No magic here its just like sending you a file just shorter (copy text to your script editor and hit ctrl enter):

file -f -new;

sphere -p 0 0 0 -ax 0 1 0 -ssw 0 -esw 360 -r 3 -d 3 -ut 0 -tol 0.01 -s 8 -nsp 4 -ch 1;

shadingNode -asShader blinn;

sets -renderable true -noSurfaceShader true -empty -name blinn1SG;

connectAttr -f blinn1.outColor blinn1SG.surfaceShader;

shadingNode -asTexture checker;

shadingNode -asUtility place2dTexture;

connectAttr place2dTexture1.outUV checker1.uv;

setAttr "checker1.color1" -type double3 1 0 0 ;

setAttr "checker1.color2" -type double3 0 1 0 ;

connectAttr -force checker1.outColor blinn1.specularColor;

setAttr "place2dTexture1.repeatU" 8;

setAttr "place2dTexture1.repeatV" 8;

sets -e -forceElement blinn1SG nurbsSphere1;

Now if you render you have a gray plane with red and green specular colors. Its like having 2 separate blinn shaders, except you only have one wich does the same thing as 2 separate ones. Ok that's simplistic you can connect different values too you fdont have to contend with just specular color, you can connect them all. In fact you can connect a continious noise function that affects many values:

file -f -new;
sphere -p 0 0 0 -ax 0 1 0 -ssw 0 -esw 360 -r 3 -d 3 -ut 0 -tol 0.01 -s 8 -nsp 4 -ch 1;
shadingNode -asShader blinn;
sets -renderable true -noSurfaceShader true -empty -name blinn1SG;
connectAttr -f blinn1.outColor blinn1SG.surfaceShader;
shadingNode -asTexture noise;
shadingNode -asUtility place2dTexture;
shadingNode -asTexture ramp;
connectAttr place2dTexture1.outUV noise1.uv;
connectAttr -f noise1.outAlpha ramp1.vCoord;
sets -e -forceElement blinn1SG nurbsSphere1;
connectAttr -force ramp1.outColor blinn1.specularColor;

Ok you now have  sphere that has a funky sheen, you can boost the values if you wish. Ok so far we have been using values That depend on position and texture coordinates. You dont need to just do that all inputs have same effect just different manifestations. The value your driving does not need to be a color, it doenst need to be based on 2 or 3d texturing, it can be based on camera surface angle or anything really. Such as vertex color which automatically blends form one vertex to another (you may want to use this but still i think noises even better). Now the chain can be arbitrarily long. (now i would use some sort of noise not this one but some better one to do this along with facing ratio)

Now so what you want to do is

1 assign each separate thing with a vertex color,
2 merge them all merge vertices.
3 drive your specular by that vertex color

Hopefully  thinking the right way around makes it MUCH easier to get the grips of what you want to get done.