Dynamics render node

Saves the state of a DOP network simulation into files.

The Dynamics output driver generates simulation state (.sim) files from a dynamics (DOP) network. Each file contains the complete state of the simulation for a certain frame. You can then read the state back into the network using a File DOP.

Saved state files are a persistent cache of a simulation. You can move these files around to run the simulation in one place and use the results in another. For example, you can use the hscript standalone utility to run a simulation on a renderfarm and save out state files, then play the simulation back locally by loading the state files with a File DOP. This would let you run multiple versions of a simulation on the renderfarm overnight and compare the results the next day.

Parameters

Render

Begins the render with the last render control settings.

Render Control

Opens the render control dialog to allow adjustments of the render parameters before rendering.

Render with Take

Uses the settings in a particular take while rendering. Choose “Current” to use the current take when rendering.

Valid frame range

Limits the rendering of frames, when set to “Render frame range” or “Render frame range only”.

Render any frame	Allow the renderer to render any and all frames.
Render frame range	Only render the frames in the range set below, but allow the renderer to render other frames if they are referenced by in-range frames.
Render frame range only (strict)	Only render the frames in the range set below, and don’t allow the renderer to render other frames, even if they are referenced by in-range frames.

DOP Path

The DOP network to render from. (You can point to a DOP within a DOP network, but Houdini saves the state of the entire network.)

Output File

The file to save the simulation state to. Make sure to include $F in the filename to write out separate files for each frame.

Initialize Simulation OPs

Force all simulation OPs to be reset. This includes DOP Networks, POP SOPs, and other OPs that cache their results.

This is the safest way to render out a simulation, because it starts the simulation from scratch and discards any partial simulations you might have done with different parameters. However, throwing away an already-cooked simulation can be expensive, especially for relatively slow solvers such as fluids.

Compress .sim Files

Determines if .sim files written to disk for caching will be compressed. Compression can reduce the size of the disk cache significantly, but can also increase the time to cache significantly. If loading or writing to cache seems slow, try using uncompressed .sim files, especially with fluid sims.

Scripts

Pre-Render Script	Run this HScript before any rendering.
Pre-Frame Script	Run this HScript before each frame.
Post-Frame Script	Run this HScript after each frame.
Post-Render Script	Run this HScript after all rendering.

Note

To access the current simulation frame $SF from the DOP simulation, the Output File should be:

baked.`dopframe(chs("./doppath"))`.sim

and the frame range Inc should be:

ch(chs("./doppath")+"/timestep")*$FPS

Usages in other examples

Example name	Example for