Infection Solver

An infection solver is a dynamic system in Houdini designed to propagate an attribute or variable across neighbouring points based on defined rules. These rules can leverage factors such as proximity, connectivity, or specific attributes like temperature, stress, or custom data fields.

This concept has been widely explored and applied in various creative and technical contexts, such as procedural animation, VFX simulations, and interactive systems. In this guide, we'll cover the foundational mechanics of building an infection solver, providing you with the essential techniques to expand and customize it for more advanced use cases.

Add a scatter to the chosen base geometry and in 2 attribute creates, initialise: @infected (initialized to 0) and @infection_time (initialised to -1).

We also want to have a source for our infection, this can be done manually or randomly, I'll use random for now. This can all be done in a point wrangle.

Now we have some geometry and attributes to work with we can move into a solver. Create a blank solver and jump inside, we're going to be working within a point wrangle. The base concept is we want the infected points to infect the non-infected points around them.

You can customize the infection solver in various ways to make it more dynamic or complex:

• Add decay: Implement a decay mechanism where infection subsides after a certain time.

• Weighted spread: Use an attribute like temperature or distance to influence the likelihood of infection.

• Growth rules: Instead of a simple binary state, use more states (e.g., healthy, infected, recovered).

Here’s an example with a decay mechanism:

This basic infection solver lays the foundation for more advanced simulations and artistic effects. Once a base system has been established, it can extend to work with particles, volumes, or even procedural animations.