Color Ramp & Density In Fluids

[user_deleted]

Hi guys,

I need to change my fluid color related to the density, so where it's more dense it is for example red and where it's less dense it's green.... so I created a color ramp in the color section of the fluid shape and mapped the color input attribute to the density.... but when I hit play the fluids get just the first color and I don't understand why....

thanks for any suggestions

[allegro]

Depending on your fluid's settings, you may need to adjust the input bias, however it should work no problem simply by putting your colors in. If you have adjusted the input bias, set it back to 0. If you have your slider all the way to one or the other side, of course you'll only see one color from your ramp. Note that in this screen grab, the view port is in shaded mode, and also note that this is a 2D fluid... if you're using a 3D fluid and you don't have any forces pushing your fluid around, it may appear to be the same color as you would be looking through a fairly uniform volume.

[duncanbrinsmead]

A basic confusion in the 3d case is that the less dense outside of the fluid obscures the more dense inside, (like a gumball) so it is hard to see the range of colors. In general one needs to define the color in a different way than the opacity in order for the color range to be very noticable on a 3d fluid.

Duncan

[user_deleted]

Thanks a lot guys

[12monkey]

hi Duncan.

Sorry I didn't quite get it, what is the different way of defining color?

Thanks

[allegro]

One could push particles through the system and render the particles, or you could have temperature/fuel reactions for color and incandescence instead of linking them purely to density.
And you can start playing with the texture settings which will help.

[12monkey]

Thanks for the reply Allegro

But as long as you hook up opacity with density, the outer fluid will still obscures the inside no matter what color method you use. And only way to see the range of colors is make the opacity really low or texture the opacity and hope the texture could slice into the fluid and let us see something inside. And Im talking about 3D fluid since 2D fluid's range of colors are always clear.

[allegro]

If you load up a couple of the fluid examples, you can see a couple of different files that will give you insight into coloring your 3D fluids. Go to your menu, and select Fluid Dynamics->Get Fluid Examples

In the Explosions folder, is Blast.ma a non-dynamic explosion type of effect.
In the Fire folder, is the flame.ma
and in Space, is Meteor.ma

Hopefully looking through these will give you a better idea of how Color, Incandescence and Opacity can be used to have some nice 3D fluids.

Unfortunately for your case where you specifically want it colored based on density... I don't know exactly how to help without knowing what's happening in your file... if you make the outside too opaque, you won't be able to see what's on the inside, and if you make the outside, too transparent, you won't be able to see it... so as I said, hopefully the above files give you ideas...