Combining Dynamic Paint Displacement With Fluid Sim - Island Emerging From Sea?

I have an animated island forming from the bottom of a ‘bathtub’ by using dynamic paint displacement with the canvas ‘incremental’ option turned on. Starting at frame 250, particles rain down on a the bottom of the bathtub and build up a ‘volcano’ until frame 500. Quite happy with that.

In the same scene, I have a fluid simulation that uses that same bathtub (the one being displaced) as a fluid obstacle.

All this is contained in a domain with a fluid object to initially fill the bathtub about 25%. The fluid simulation starts at frame 1 (well before the displacement starts).

So what I want to see is the bathtub about 25% full and becoming relatively calm by frame 250. Then I want to see the island begin to form. As the island pushes up, I want to see the water spilling off it and the fluid level in the bathtub rise slightly.

Anyway, I have the fluid simulation working and baked,and I have the dynamic paint displacement working and baked, but I am not seeing the right effect. The fluid just doesn’t see the island.

I am missing a concept regarding whether this is even possible to simulate, and how I should be baking and/or applying the modifiers. The bathtub has the fluid sim (obstacle) modifier above the dynamic paint modifier (displacement). I feel like I need to move the dynamic paint above the fluid, but Blender won’t let me do this because “cannot move above a modifier requiring original data”. I tried baking the dynamic paint and then applying the dynamic paint, but I clearly don’t know what I’m doing - all of the animated displacement disappears.

I saw another post where it is possible to combine hair and cloth if you get the modifier order right. But I don’t seem to have any choice in my case. So what am I missing? Is it even possible?

I’ve attached a .blend if that helps. Bake the dynamic paint, then bake to fluid sim to duplicate my actions.



DynamicPaintDisplacementWithFluid02.blend (377 KB)

i havn’t looked at your file, nor have i used dynamic paint with the fluid sim ( i have enough trouble with the fluid on its own without complicating things :smiley: ) but i wonder if you made your canvas a collision object in the physics panel, would that help any?

Just tried that, but the fluid sim cannot see the bathtub at all in that case Sort of as expected, the fluid does not fill the tub, just spills straight to the domain. In my .blend, the bathtub is a fluid obstacle and it does the initial filling fine. Its just getting the later animated displacement to be recognized that’s the problem. Thanks for the suggestion though!