From Valve Developer Community
- Render Rope
- This render type renders the particles as a ribbon or rope, connected in series from the oldest particle to the newest. Ropes require a specific .vmt type to render properly - it must have $splinetype set to 1 or 2. Additionally, ropes which have $orientation 3 set in their .vmt will use the normal to render oriented to the per-particle normal.
- subdivision_count [integer]
- The number of polygons, or subdivisions between each particle. More subdivisions will create smoother curves at a performance cost.
- texel_size [float]
- The visual density of the rope along its length. Quite small numbers may be required.
- texture_scroll_rate [float]
- The rate at which the texture will scroll along its length
- The offset to the initial texture placement. Note that as each new particle is created or as they move, the rope will "scroll" along the length to maintain the specified texel density.
- scale CP start/end
- Setting these two control points which switch the texture mapping mode of the ropes to be relative to the two control points. This will allow the other "scale" options to work.
- scale texture by CP distance
- If set, will treat the texel_size as relative to the distance between the two control points, with 1 being a single span of the texture between the two.
- scale scroll by CP distance
- If set, will treat the texture_scroll_rate as relative to the distance between the two control points.
- scale offset by CP distance
- If set, will treat the texture_offset as relative to the distance between the two control points.