Fake Caustics (Dot Product)

  • June 13, 2016
  • Blender 2.7x
  • Render: Cycles
  • Creator: janmatys
  • License: CC-0
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Hi there,

here is a SIMPLE fake caustics simulation made using the dot-product. The fakes looks real enough to be used in a renderings and its made as a PUBLIC DOMAIN so feel free to use it anywhere, anytime and anyhow U like ;).

Sincerely, JayM


  • mramshaw profile picture

    Cool idea, materials are not labelled so a little explanation might be nice.

    The IOR of 1.45 seems wrong but the material looks pretty good.

    Thanks for sharing, I gave an upvote and a like.

    Written June 14, 2016
  • janmatys profile picture

    OK, sorry for that mate...

    DotProduct is simple I guess so lets move on to Colour Ramp ... used to control the colour of the shadow under the sphere so feel free to adjust it to needings of Your scene or to make a pretty good looking AO effect without computing it ;).

    The mix node after rulez the strength of the effect no matter if positive or negative number and the rest of the nodes is self-descriptiove imo. BTW I think IOR of 1.45 for the glass is REAL cause the IOR of the glass (depends on the structure for sure) is between 1.44 and 1.90 mate.


    Edited June 22, 2016
  • mramshaw profile picture

    Thanks for the explanation.

    My memory is a little hazy but I think I understood the nodes, even so the colour ramp comments are helpful.

    No, I think my main problem was that I wasn't sure where you were going ... I looked up some IORs to figure out what 1.45 might be (aluminium? no, don't think so).

    1.45 was listed for some special type of glass, and your material does look like glass ... but as you hadn't named the material I really wasn't sure what you were going for.

    Or at least that's how I remember it. Anyhow, thanks for the comments.

    Written June 24, 2016
  • dufloch profile picture

    Hi, nice shader. Would it be possible to use this trick to have also reflection caustics?

    Written June 22, 2016
  • mramshaw profile picture

    I wouldn't think so. The shape of them seems to be mostly determined by micro-structure (meaning waves and wavelets).

    So when you see them (and they seem to be pretty rare), they are often 'dancing'.

    Not sure, but I think you would have to invert the dot product.

    Anyhow, reflection caustics always look very weird, this is a good approximation of refraction caustics though.

    Written June 24, 2016
  • janmatys profile picture

    Simple, YEP this is NOT for reflection ones.

    And THX shaw! ;)

    Edited July 30, 2016
  • joshuapetrofsky profile picture

    what would be a way to fake dispersion, normals, volume, and glass color in dot product caustics?

    Edited January 11, 2017