say i take a cube of water

how would i get the "depth" or "thickness" to show in it as darker as with real water?

currently whenever i see water, its always as if its a single plane tinted blue, which always looks fake to me, rather than showing depth, to show its an accual liquid filling that space

can't use a shader to simply color it darker, as that also looks a bit too fake

any ideas?-.-

pure water (with nothing but h2o) doesn't darken AFAIK. it only darkens with depth if particulates/microscopic life forms are present.

Attached Link: Fake liquid absorbtion

CD World 85 had a free version of RealFlow4. (Limited to 50,000 particles) that may still be available and a help?

pure water (water was only an example to explain my goal) does darken with depth, the existence of other particals will influence and speed up how much light is absorbed though. proof of this can be found by taking a piece of pipe, capping both ends with a clear see-through material say glass, and fill with highly filtered water, or so you can't claim not clean enough, buy some hydrogen and oxygen and make your own water =P the degree of absorbtion is different, but it still happens

mark, the technic in your post is using color change based on the elevation of the part of the model, which is basicly the same as attaching a color map to fake it, no offence just trying to avoid that -_- 

wonder if a shader plugin can be wrote to measure the length of rays (after taking into account raytracing effects)  as they travel "inside" of an object, and provide a color gradient for it to color the model that way?

Mark did say it was fake.  What you're looking for is custom programming similar to what was used for the remake of The Poseidon Adventure.