so I'm trying to recreate this effect https://twitter.com/Erisdraw3D/status/1056931358185086976

and I've gotten as far as having the white area around a rock, but I've been struggling with animating the area where the brush touches the canvas. Eris gives a few notes on how he did it, but I haven't been able to follow them. Does anyone have a more detailed step on how to use noise texture to only affect the Brush area of effect?

Thank you


1 Answer 1


It sounds as if you've done most of this already.. but will illustrate anyway..

The Canvas

A plane, subdivided sufficiently for resulting texture resolution.

  • Format: vertex colors, as per your example, no effects (Drying, etc)
  • We're only interested in the Paintmap

enter image description here

The Brush

  • Color, White, this is just going to be a mask, Alpha: 1, this example isn't overlaying anything.
  • Wetness: 1 - the full 'load' of paint should be available immediately
  • Proximity will do, we can't see inside the rocks
  • A Color ramp for falloff. A nice soft falloff will expose the waviness of the noise in the material, gradually decreasing away from the rock. Also provides another adjustment for the final effect.

enter image description here

The Brush, on its own:

enter image description here

The Nodes

Here, the Brush color is used as a multiplier on an animated Noise texture, before the product is put through a threshold in a Color Ramp, as part of the river's material.

  • If you've UV mapped your river, you may want to use that texture coordinate.
  • The Y location in the Mapping node is keyframed to make the Noise 'flow' down the river
  • An Attribute node is used to pick up the vertex color layer. Just enter its name in the text field.
  • Strictly, I probably should have used the 'Fac' output of the noise node for a 0 to 1 output, but clamping the multiply and tweaking elsewhere seems to be enough

enter image description here

The result - tweak the brush Falloff, texture scale, threshold in the Color Ramp, to vary the effect.

enter image description here

  • $\begingroup$ By painting with a stream of particles emitted from the rock, instead of just the rock itself, you could bias the effect in the direction of flow. (more below the rock than above it) introduce turbulence, 'bubbles', etc.. but that would be a lot of tweaking.. maybe another question.. :) $\endgroup$
    – Robin Betts
    Dec 2, 2018 at 14:55
  • $\begingroup$ Thank you so much Robin! I think the one thing that I was struggling the most is understanding which part of the dynamic paint affects the brush's color, and from what I understand the canvas projects all of that information, the brush is just for coordinates? I'm still trying to get my head around Blender nodes, so this definitely helps a ton! $\endgroup$
    – bgall44
    Dec 3, 2018 at 5:50
  • $\begingroup$ @Ben The DP metaphor is quite complete.. a Brush 'carries' a flow of colour, which it 'deposits' from its current location into some form of storage associated with the canvas each frame. The storage can be vertex colours or weights, displacement, or a texture. The Canvas decides what happens to the accumulated colour .. drying, spreading, etc. This example doesn't use any of those canvas effects- just using a colour of (1,1,1,1) as a mask. To imitate the example you gave, set the paint to dissolve instantly in the canvas, so when you lift out the rock, the effect disappears $\endgroup$
    – Robin Betts
    Dec 3, 2018 at 8:19

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