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So i have been trying to recreate a specific material in blender for quite a while now, but i just can' seem to get it working. the picture attached shows what i am trying to recreate, basically what you would see if you were to put a mold capsule under a microscope, very translucent, but not reflective almost gelatineous, but more importantly i want to get the effect where it darkens as the material gets "thicker" around the edges and such. i would show my progress, but i really haven't done anything substantial other than messing with subsurface nodes and translucency nodes, i don't even know where to start as far as the darkened edges go. mold spores under microscope

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  • $\begingroup$ Have you used available vectors and a dot product? $\endgroup$
    – atomicbezierslinger
    Apr 16, 2019 at 18:49
  • $\begingroup$ as atomicbezierslinger says in his answer, Input > Fresnel or LayerWeight nodes may help you $\endgroup$
    – moonboots
    Apr 16, 2019 at 19:01

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Dot Product and Fresnel

In your nodes you should consider the dot product node depicted in the image below or fresnel node

  • VectorA • VectorB

    • computes the strength of the parallel component for the two vectors as a scalar.
      • VectorA and VectorB are normalized for ease of understanding.
      • A result of [1.0] would mean the vectors are parallel
      • A result of [0.0] would mean the vectors are orthogonal
      • A result of [-1.0] would mean the vectors are antiparallel

  • In the image provided in the question the color is different at the glancing angles and more transparent when looking directly at the faces of an imagined 3D model.

  • [viewing vector] dot product the [face geometric normal vector]

  • Using the result of VectorA • VectorB can be used to determine the mix of two colors or transparency and et cetera. When they are not so parallel use different color. vector1 and vector2 can be normalized. When the dot product is close to zero [0.0] then the vectors are at right angles. You will be able to identify looking at the edge silhouette or directly at a face. Experimenting with this will be a start.

  • dot product and those vectors are available in the nodes

enter image description here

https://en.wikipedia.org/wiki/Normal_(geometry)

https://en.wikipedia.org/wiki/Dot_product

This has been used in 3D CG long ago 40+ years

enter image description here

Image above with dot product calculations. When your viewing vector is more orthogonal to the [face normal] the color will be more opaque. When your viewing vector is more parallel to the [face normal] the color will be more transparent. Transparent factor is the property that was designated to be affected by the calculation.

  • Please also secondarily search Fresnel which is related.

  • Depending on your models. You could consider textures and the compositor.

  • At this moment this is not a tutorial. I am trying to give you some quick action tips.

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  • $\begingroup$ Hi, thank you very much for a good answer, these are great tips and just messing around a little with fresnel and dot product i have already gotten much more pleasing results! $\endgroup$
    – Stag beetle
    Apr 16, 2019 at 19:37
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    $\begingroup$ Good. The best way to convey that is to ... upvote this candidate answer or downvote it. $\endgroup$
    – atomicbezierslinger
    Apr 16, 2019 at 19:55
  • $\begingroup$ can't unfortunately :( my account is too new so it doesn't let me add an upvote, but thanks for the great tips. $\endgroup$
    – Stag beetle
    Apr 16, 2019 at 20:18

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