I've got a semi-transparent outer block, and two semi-transparent inner blocks. I'm trying to animate the inner blocks fading out by bringing the transparency alpha to zero. I'm using Blender Internal.

My model looks like this:

enter image description here

These are wax blocks, with objects embedded inside. First, the small inner blocks are created separately as 2x1 blocks. Then they're placed next to each other to make a large 2x2 block. Once the outer wax is in place (a boolean modifier/plane reveals the outer wax) the inner wax should fade away, "melting" as it's replaced by the the outer wax.

The problem I'm having is that the sharp edges of the inner wax don't fade away as alpha approaches zero. My guess about what's going on is the amount of light that's reflected off the inner faces is unaffected by their material's transparency.

Effectively, I don't like the discontinuity between when alpha is very small, and when alpha is zero. Here's is the difference between the inner blocks transparency alpha at 0.001, and 0.000:

enter image description here enter image description here

  • $\begingroup$ Would it work to delete the inner face? (or give it some thickness?) $\endgroup$
    – gandalf3
    Oct 14, 2013 at 2:59
  • $\begingroup$ Hmm.. I'm not sure exactly what you mean by giving it thickness, but I could give it a try. The inner blocks are outside and off by themselves earlier in the animation though, so I don't think deleting the face is an option. $\endgroup$
    – ajwood
    Oct 14, 2013 at 3:12
  • $\begingroup$ I'm not entirely sure what you want. could you upload your .blend or make a mockup of how you want it to look? (nvm about giving it thickness, I thought that the inner block was one object with an internal face) Also, just to be clear, is the "nasty edge" an intersection of the two inner block objects? $\endgroup$
    – gandalf3
    Oct 14, 2013 at 5:58
  • $\begingroup$ See if my edits make more sense.. if not, I'll do up a .blend file. $\endgroup$
    – ajwood
    Oct 14, 2013 at 15:11
  • 1
    $\begingroup$ Is it time for the author of the question to post an "answer" which outlines the pros and cons of the various fixes he tried (with credit to the originators) and which he settled on as the "solution" to his specific problem ? $\endgroup$
    – Mutant Bob
    Feb 25, 2014 at 15:24

1 Answer 1


Turns out the problem goes away if I switched the transparency of the outer block from raytraced to z-transparency.

enter image description here


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