Particle Fluid Surface surface node

The polygon size to use when polygonizing the surface.

This SOP generates geometry using an implicit function similar to the one used when generating geometry around metaballs. Namely, each particle in the input has associated with it a radius of influence in which it can affect the surface. Initially, this radius is established by each particle’s “pscale” attribute. This parameter scales that radius of influence. Increasing this parameter causes each point on the generated surface to be sampled from a larger set of a particles. This means that the resulting surface may appear smoother, but will also have less detail. Similarly, decreasing this parameter causes each point on the generated surface to be sampled from a smaller set of particles, potentially resulting in more detail at the cost of making the surface less smooth.

Average Position, or Metaball.

Controls the thickness of the surface around the particle field. Larger values here create a surface which lies farther away from the fluid particles. Smaller values may force the fluid surface to wrap the particles more tightly, but may also cause the surface to lie inside of the particle field. This parameter is scaled internally by the Point Radius Scale parameter.

Increasing this parameter has the effect of tightening the surface around the fluid particles.

Specifies the interpolating metaball kernel.

Specifies the weight of each metaball.

When this option is enabled, particles with no neighbor’s within their support radii are excluded from the surfacing calculation.

Only generate surface polygons inside of the explicitly specified bounding box.

The minimum boundaries of the user-defined bounding box.

The maximum boundaries of the user-defined bounding box.

When this option is enabled, volume primitives specified in Input 2 are subtracted from the fluid surface.

The distance from the collision volume at which subtraction occurs.

Specifies the list of point attributes to transfer from the particles to the fluid surface.

Computes normals based on the gradient of the fluid density.

When this parameter is enabled, the SOP stretches the surface in the opposite direction of each particle’s velocity vector.

Speed stretching is accomplished by making copies of a particle along its velocity vector. This parameter controls the number of copies of each particle that are used.

When this parameter is enabled the distance at which particles are trailed behind input particles is scaled on a per-particle basis by the particle scale of each input particle. This is useful when inputs to the SOP have varying particle scales.

Each input particle is stretched according to the length of its velocity vector scaled by this parameter.

The maximum distance that any particle may be stretched.

Setting this parameter to anything other than one will cause the duplicated stretch particles to differ in size from the original particle. This controls the ratio in size of the smallest stretch particle (which is positioned farthest away from the original particle) to the original particle.

Enables/disables the filtering feature.

Filtering is an iterative process. This parameter controls the number of filter iterations to perform. Increasing the number of filter steps further smooths out details in the generated surface and, depending on the Filter Tightness parameter, may cause the surface to further shrink around its input particles. More detailed geometry (surfaces with smaller Step Size parameters) will require more steps to achieve the same effect as less detailed surfaces.

When this SOP generates a surface, it computes surface density values on a grid with cell sizes specified by the Step Size parameter. Filtering is achieved by blending together values from each grid cell and some number of adjacent cells. This parameter controls the number of grid cells involved in each blend operation.

Increasing this parameter causes the filtering operation to “shrink” the generated surface. This effect can be used to move the generated surface closer to the input particle field.

When this parameter is enabled, attributes transferred to the surface also have their values filtered.