Houdini 21.0 Pyro

Pyro Configure Fire

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Overview

There are several Pyro Configure examples available through the tab menu. These are similar to shelf tools that put down networks of nodes for learning purposes. The Pyro Configure Fire example illustrates a fast moving fire. It shows a minimal fire setup that can be used as a template for building fire in your scene.

Important nodes

SOURCE

Wire a Mono layer into this node to adjust where the smoke emits from. This node controls the thickness of the fire emission. A value of 0 will have no fire and 1 will have the full thickness.

pyro_configure1

Adjusts the resolution of the fire. This is the number of voxels across the default imaging window. Higher resolutions will take considerably more time and memory.

layertovdbleafpoints2, pyro_sourcefromlayer2, pyro_sourcefromlayer3

The VDB has to be activated so you can source into it. Layer to VDB Leaf Points handles the activation from the SOURCE layer, while the Pyro Source from Layer handles the actual sourcing. The thickness and inputs for these two nodes should match.

pyro_block_begin2

The start of the simulation loop. All nodes inside the convex hull (highlighted area) will run every simulation step. The simulation is clipped from -1 to 1 by default, and can be controlled by modifying the Clip X/Y/Z parameters.

pyro_dissipate2

Controls how fast the temperature decays. Temperature is used for the glow of the fire, so a slower decay will result in longer flames.

pyro_lightambient2

Computes lighting for the fire’s smoke using an ambient light source. Increasing smoke density (with the Density Scale parameter) increases the contrast of self-shadows.

rasterizevolume2

Renders the fire into a layer. The camera_ref can use an imported camera from the Camera Import COP to change the view or resolution of the render. The Emission parameters can be used to make the fire brighter or control the envelope of the glow.

Learning from this example

To...Do this

Create different fire sources

Change the input to SOURCE. You can use any shape, or even a Font COP to make the smoke sourced from text.

Slow down how fast the fire moves

Reduce the Scale on the pyro_buoyancy1 node to 100. The default is 1000, which produces very fast moving fire. Lowering this value creates more lethargic flames.

Create smoother flames

Reduce the Amplitude on the pyro_tubulence1 node to 0.5. The default is 5, which rips the fire apart.

Pyro

Sparse Pyro

Pyro instancing

Legacy Pyro

COP Pyro