Trying to understand ‘best practices’ and the ‘why’ of Houdini.

I noticed that if you create an AutoDopNetwork, that Houdini adds the gravity at the very end, even after the static solver.

Is there a reason for this?

It's also hard for me to understand how gravity can affect the Rigid Body Solver even when it's downstream.

Just trying to understand how Houdini works.

Thanks,

Jim

it's important to view the video tuts and the Master Classes
DOPs isn't a network like SOPs…it doesn't just run top down.

This page also explains how DOP works:
http://www.sidefx.com/docs/houdini15.0/dyno/top10_medium [sidefx.com]

Yeah, I have been watching some other tutorials on DOPs, which is why I have my question.

I've watched one masterclass on DOPs, but it didn't explain any of the hows and whys of the layout and inner workings.

Thanks for the page, that explains a lot.

reelinspirations
I noticed that if you create an AutoDopNetwork, that Houdini adds the gravity at the very end, even after the static solver.

Is there a reason for this?

The Static Solver ignores gravity data but a Gravity DOP is added to the network because you likely will later add something that should be affected by gravity. Using a standard layout with placeholder merge nodes makes it easier to write shelf tools that need to manipulate the DOP network.

reelinspirations
It's also hard for me to understand how gravity can affect the Rigid Body Solver even when it's downstream.

The DOP network basically performs two passes when it cooks each frame. The first pass evaluates nodes in the DOP network. In most simple simulations, the DOP nodes introduce objects and data into the simulation during this pass on the first frame and do nothing on all later frames. The second pass runs the solvers that have been applied to objects in the simulation. In most simple simulations, nothing happens on the first frame during this pass but on later frames the solvers update simulation objects to reflect the passing of a timestep.

It doesn't matter which order the Rigid Body Solver and Gravity DOP are applied because the gravity data is added to the simulation during the first pass and the Rigid Body Solver discovers the applied gravity data when it is run during the second pass.

The Geometry Spreadsheet is really helpful in understanding what is happening during a simulation.