Attribute control is some of the most important things you can do in gore sims.

If you are working with FLIP simulations, or POP Fluids, you most likely will be working with various attributes. Mass, velocity, density, etc. A lot of these attributes can be controlled and set up pre-simulation.

For example, let’s say your goal is to create an accurate simulation of a head explosion. There is going to be the initial pop of the skull cracking open, the blood and flying debris, the blood pouring out from the neck, slower blood trails flowing over the neck, etc. You'll have a lot of simulations to layer, and need to set that up extremely efficiently. Not to mention, control the overall timing of everything.

When creating simulations, 90% of the problem is always something to do with the emitter. 90% of your time will be spent modifying it, and the incoming attributes. Simulations just take the information they are given, and act accordingly on them.

By controlling attributes such as viscosity, mass, velocity pre-simulation, you can move faster through your simulation. Plus, if you edit attributes pre-simulation you don’t have to wait for the simulation to playback to see the changes, switch houdini over to manual, and have more confidence that the changes in the attributes are correct even before they are simulated.

You can easily create sliders and fit statements in Houdini with attribute wrangles for attributes to accurately animate timing of attributes to your shot. For example, let’s say your supervisor wants the velocity of the blood from your character’s neck (post head explosion) to slow down with each spurt over time. You could use this wrangle method to slowly decrease the velocity vectors over time. Which in turn will lower the starting velocity per frame.

This method is also great if you have multiple holes that gore needs to be emitted from, but need different areas to emit liquid with different speeds.

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