Vellum "Fluid" Sim

To get the Droplet and Fabric to interact, I used Vellum Grains for the Droplet, and Vellum Cloth for the Fabric, instead of FLIP interacting with Vellum.

To get fluid like motion on the grains, I applied POP Fluids DOP node only for the grains.

Simulation Retime

The resulting simulation was then retimed separately (between droplet and fabric) to get the most appealing motion.

Since it was retimed separately, the fabric and droplet was out of sync and were intersecting. To solve the issue, the droplet's position was offset based on the fabric's deformation starting from when it collided so that it keeps the same distance to the fabric as it deforms.

Droplet Interpolation Shaping

To achieve the iconic water droplet shape instead of a simple spherical blob, the droplet's position between the current frame and the previous frame was interpolated in-between while also scaled based on an art directable curve.

Droplet Surface Tension Shaping

To mimic the look of the surface tension as found in the reference (found at the bottom of the page), a cross section of a retimed, slower droplet was "draped over" the current frame of the droplet (which is smaller than the cross section) using a ray node and an attribute blur.

That same geometry was once again "ray-ed" on to the displacement texture of the fabric to have it seem to be interacting with the intricate details of the fabric


The wetmaps are then simulated baed on data from the post processed droplet and the fabric.

Flipbook of Final Geometry

Texture Generation

The specific details and patterns of the fabric were generated procedurally. It starts from a drawn curve which was then mirrored, added a cosine wave to get that weave shape and copied onto a grid of points which were selected according to a hexagonal shape. This hexagon is then copied and transformed into a grid of hexagons. which is in essence the texture pattern.

Initially the idea was to render the fabric as this detailed geometry however it proved too heavy to render so it was turned into a displacement map by rendering the texture top down with an orthographic camera and with a Z-Depth AOV. The AOV is then cropped and resized to have the ability to tile the texture on the simple grid geometry which was simulated as the fabric.


cloth photographic reference

recorded water absorption reference

© 2019 By Erhardian Siswadi.

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