This week will be about volume and smoke, fire or explosion.

In Volumes, we will learn to create and control combustion style simulations in the sparse pyrolysis solver, and then further study by running a bunch of wedge simulations using PDG so that we can work more efficiently. Custom simulation and post-simulation techniques, as well as custom shaders and lighting strategies, will allow us to create production-quality works in ways not possible with out-of-the-box tools.

Atmospheric volume

This shader simulates light scattered by a thin, uniform atmosphere. It produces optical axis and volumetric shadows cast from geometric objects. It is suitable for point light sources, spotlights and area light sources, but not suitable for distant or skylights. This is a scene-wide volume shader.

Smoke:

Time Scale-Specify a scale factor that relates the DOP time to the simulation time of this microsolver. A value greater than 1 means that the simulation time is earlier than the DOP time. Values less than 1 cause the simulation to appear to run in slow motion relative to the DOP time. There are multiple expression functions, such as doptime, which are used to convert global time to analog time and vice versa.
Scale-The turbulence amplitude applied to the specified velocity field.
Swirl size — Initialize the (base) vortex size value. Measured in world units. The value comes from frequency.
Particles-The amount of influence of the added turbulence zone, relative to the initial vortex size.
Pulse length-the speed at which the noise moves. A higher value will result in a slower movement speed.
Seed-defines the initial noise offset
Attenuation — Defines the gradual attenuation of intensity.
Impact threshold-When to apply turbulence based on the specified density field.
Turbulence-For a smoother transition relative to the applied turbulence level of the initial vortex size, use a lower value

fire：

First remove the temperature attributes of attribnoise and volumerasterizeattributes, increase the flame density source and target field attributes, then add interference, add gas vortex restriction and restriction scale 0.5.

Then use Gas Wind DOP to apply wind force and adjust the speed field in the direction of the ambient wind direction，and finally adjust the volume to add color.

explosion

The first input provides the source for the Pyro simulation, and the second input provides the collision for the Pyro simulation to make the density smaller and the flame effect clearer, adding density and divergence to make it expand quickly.