I created this procedural HDA in the course of my master thesis about Houdini-Unreal integration. Here is a quick rundown of the different steps.
Houdini:
First, the tool takes the input-curves and runs a simple vellum simulation over it. In Unreal, the user can adjust the droopiness of the rope by changing the rope resolution, or choosing a later simulation frame via the timeshift node.
The tool contains several prepared clothing meshes, which can all be activated/deactivated by the user inside the engine.
For each of those clothing items, the width of the bounding box is stored inside a detail attribute.
Along every input curve, points are created along the curve. The distance of each point takes into account the width of a random clothing item. Then, the points are deformed along the curve and the respective clothing items are scattered on them. For a more detailed explanation on this technique, check out Viktor Anfimovs' tutorial on aligning objects along a curve in Houdini.
For an increased realistic look, you can run the scattered clothing through another vellum simulation, before baking the HDA. This should take about 30 seconds, but that depends on the number of clothing items and the simulation frame you select. However, when testing the HDA in Unreal with the wind material turned on, I found that this last step often isn't necessary to get a good look.
Unreal Material: Wind + Patterns
The wind for the Clothesline is controlled by the World Position Offset inside the material. It offers customization of the wind strength and wind direction based on the world space UVs. The wind strength is also multiplied by the green vertex color of the clothing items, so it affects the clothing stronger at the bottom. The different color tints are based on the value of the red vertex channel, the seed of which can also be customized inside the HDA.
