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enter image description hereenter image description hereenter image description hereSlowly but surely getting the hang of using nodes in Cycles. I thought I would try to make a star sapphire. While making a cornflower-blue, translucent shiny oblong is easy, figuring out the important part (the star) isn't. Any suggestions? I was initially trying to pair a voroni-type surface with an emission shader. Didn't work. I am open to suggestions.

Due to restrictions of my system, I am using Blender 2.79. I am in no position to upgrade, because that would mean getting a whole new computer. Please do not make suggestions of upgrading my system or program. Thank you.

The top picture is the Star of India, what I'm shooting for. The bottom picture is what I have thus far. The node pic is what I've done with it. There are two other nodes, but are disconnected since they had no effect on anything.

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  • $\begingroup$ Hello and welcome. Can you edit your post to include some screenshots of what you have now and the effect you're trying to recreate? $\endgroup$
    – Allen Simpson
    Commented Sep 9, 2022 at 17:58

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Believe it or not, I used to consider myself a "master" of 2.79, and now I can't even remember what features it has, or doesn't have.

That being said, I hope much of my shader graph translates "back in time", so to speak.

The basic idea is to make the "glow lines" using the top section of the shader graph, however, this makes the lines go all the way around the object, and it seems from the sample image, that this is not the case, and that the lines terminate somewhere below the midpoint. To make this happen in the graph, I used a Gradient Texture, separated on the Z, and multiplied over the "glow lines" to darken the lower areas.

Shell

The real magic in the graph, is the use of an Emission Shader, transferring the lines into a glowing volume inside the object. This, coupled with a less than 1 alpha value for the surface lets them show through. To aid this "inner glow" I also used a transmission value of .4 and a rather large (0.5) subsurface value. I changed the subsurface radius colors to accommodate blue light passing (RGB - 0.2, 0.6, 1.0). I added the "glow lines" to the surface as well, so it seems they are on the "skin" and continue below the object's surface.

Lastly, and kind of an afterthought, I used a Noise Texture as the basis for a bump on the surface, just so it looks more irregular and natural, rather than a simple 3D spheroid.

Final result looks like this:

Shell2

I know not all of this will translate 1 for 1 to 2.79, but I hope the content contains enough of the "gist" that you can find workarounds. Feel free to ask any questions, and I will try to answer to the best of my ability.

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  • $\begingroup$ Your example exceeded my expectations. Your answer was not only clear and understandable, but kindly delivered. Thank you. While you're right, I may not be able to do 1 for 1, but I've done other Blender tutorials which used newer versions with satisfactory results. This should come out pretty good. Many thanks! $\endgroup$
    – Mike
    Commented Sep 10, 2022 at 11:50
  • $\begingroup$ Update: had to do some trial and error with the nodes. Seeing as 2.79's principled shader doesn't have a slot for emission, I ended up making an emission shader, ran it and the principled shader through a mix shader, cranked the factor and ended up with something passable. Will I do something like this again? Not unless I'm getting paid...which is unlikely. $\endgroup$
    – Mike
    Commented Sep 11, 2022 at 19:42
  • $\begingroup$ For proper emission, I recommend using a Mix Shader to combine your Principled BSDF with an Emission Shader (colored by the same node as I connected to emission in my example), using the same MixRGB node output that I used as a mix factor for the Subsurface color (the one that is the multiplication of a color burn and a gradient texture). $\endgroup$
    – Christopher Bennett
    Commented Sep 11, 2022 at 20:11
  • $\begingroup$ At first, I was trying to figure out what exactly you were saying, but then realized that was what I had stumbled upon! Thank you again! $\endgroup$
    – Mike
    Commented Sep 13, 2022 at 1:49

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