Add this tag to the object that will serve as an emitter for smoke, steam or a flame. You can find the Pyro tag in the Object Manager under Tags>Simulation Tags. You can combine it with any objects that represent geometry in the form of polygons or splines. However, for spline objects and for polygon objects that do not represent a closed volume, the Surface Emitter option must be enabled for the Pyro tag so that the Emitter for the gas can also calculate a volume from which the smoke, steam, or flames can rise.

If you want to create an explosion, you can also directly access the Pyro Fuel tag, which can be found in the same menu. This is also the Pyro tag, except that it has different presets. The calculations of Density and Temperature are switched off and only fuel is generated, which can then be converted into heat, smoke (density) and pressure by the settings of the Pyro Scene at the Pyro Output object. However, fuel can also be simulated with the Pyro tag. Switching between the two Pyro tag types is therefore possible at any time.

The Pyro tag therefore forms the basis of every Pyro simulation and automatically creates the Pyro Output object(if none is already present in the scene), which can then be used to define the simulation in more detail in the second step and also to save it as a cache file, for example. By default, the Pyro Output object's settings are taken from the defaults of the Project Settings (Simulation tab, Pyro subgroup). However, a Simulation Scene object can also be linked there, which can also be used to specify Pyro simulation settings. The Simulation Scene object can be found in the Cinema 4D Simulate menu .

A simulation of steam, smoke or fire is based on various components that can be generated individually or in combination. A steam or smoke component of the simulation can be created using the Density settings in the Pyro tag and can also be colored individually.
The typical color gradients of a flame are characterized by different temperatures, which can also be calculated in the simulation. Fuel can be added to control the heat or even the pressure in the simulation. For a continuous or varied supply of fuel to the simulation, its temperature and therefore the size and color of the visible flame can be controlled. By burning a large amount of fuel for a short time, explosions and their characteristic mushroom clouds can even be simulated. Burned fuel in turn creates a density that can represent smoke, even if no Density simulation was previously activated. All these elements can be simulated individually via the Pyro or Pyro Fuel tag. The evaluation of the fuel and the definition of Forces and calculation parameters for the smoke and temperature development, can then be found in the Pyro Scene tab of the separate Pyro Output object.