One PolyData Mapper Instead of Two: Measuring Vertex Pulling on the Desktop 

VTK ships two OpenGL polydata mappers that do the same job two different ways. We maintain both. I wrote the second WebGL2/GLES3.0 mapper back in 2023 due to a need for polydata rendering in VTK.wasm using vertex pulling. It’s called vertex pulling since it’s the vertex shader that decides which vertex data to read vs the traditional way where vertex data is supplied automatically via attributes. The historical reason for keeping them separate was a performance belief: vertex pulling is too slow for the desktop. We turned that belief into measurements on a native NVIDIA GL stack, and it does not hold up. With a two-line change: an indexed draw, vertex pulling can match the classic interleaved-VBO mapper on GPU time across every workload we tried, it carries a realistic 4-attribute vertex with no penalty, and adds zero CPU overhead per frame. The assumption that kept the mappers apart is no longer relevant. This post shows the numbers and argues we should merge the two mappers.

Polyhedron Processing Improvements in VTK

Polyhedral cells (general convex or non-convex 3D cells with arbitrary face and vertex counts) appear throughout large-scale simulation, particularly in CFD. Some solvers produce them as the dual of a tetrahedral mesh; others use them as transition cells across refinement boundaries; still others build directly on face-based polyhedral connectivity as the native primitive. Several commercial and open source CFD codes have invested in face-based arbitrary polyhedral cells as a first-class primitive, and that investment runs all the way through the pre- and post-processing pipeline because handling polyhedra well at every stage is non-trivial.

Post-processing Smoothed-Particle Hydrodynamics (SPH) using ParaView

Following Kitware’s participation in the PARTICLES25 conference last October, including the presentation of a survey paper, this article provides an overview of current approaches for post-processing SPH data in ParaView.

Smoothed Particles Hydrodynamics, or SPH for short, is a mesh-free fluid simulation method used in a variety of fields, including hydrodynamics and astrophysics. SPH uses particles to represent mass: each particle has a position, a velocity, and discretizes continuous fields such as pressure in space using kernel functions around their position. Many physics solvers using SPH, such as DualSPHysics or OpenRadioss, can run in parallel on supercomputers, simulating billions of particles at once. This creates a challenge for visualization, as direct rendering of a large number of particles as points or spheres does not always give scientifically interesting results.