The Explosia FX Source Tag

This tag must be added to any object intended to be used as a source for an Explosia solver. It controls the initial parameters for the burn model.

Interface

The tag's interface looks like this:

Parameters

If you click the little black arrow next to the labels, additional parameters are made available. In the above screenshot, only those for smoke are shown, but they are identical for the other four parameters.

These additional parameters are:

Custom

This drop-down menu allows you to specify what area on the object is used by the solver as the source of the smoke or heat etc. Normally this is the entire object but you can set this menu to Tag or Texture.

If 'Tag' is selected, you can drag a selection tag, vertex map tag or texture tag into the 'Tag' field and then only that part of the object is used as the source.

If 'Texture' is selected you can add a shader or bitmap to a 'Texture' field to specify the area to use as the source.

Tag

A link field for a selection tag, vertex map tag, or texture tag if 'Custom' is set to 'Tag'.

Texture

A field for a shader or bitmap if 'Custom' is set to 'Texture'.

Important notes when using textures to control burning

1. Explosia actually samples the source object per-vertex. What this means is that a texture is only sampled at the points where there are vertices in the object. If you have an object with only a small number of vertices the texture may appear to have no effect, or you may see no burning at all, depending on the texture sample at each vertex. Therefore, to use textures effectively, make sure your objects have plenty of vertices to ensure the texture is sampled adequately.

2. When textures are rendered in Cinema 4D, this is normally a multi-threaded process. But sampling a texture tag without a full render can only be single-threaded - there is a risk of random crashes if multi-threaded sampling is done outside an actual render. This does not apply if shaders are sampled directly. The result of this is that if you set 'Custom' to 'Tag' and drop a texture tag in the link field, sampling is single-threaded and therefore much slower than if you set 'Custom' to 'Texture' and add a shader or bitmap directly to the 'Texture' link field.

Solid

If this is checked, the object is treated as a solid and its surface is used as the source. If it is unchecked the object's volume is used as the source.

Smoke

Smoke is normally generated from fuel, but this parameter lets you generate it independently. The value is zero by default, but if you set 'Fuel' to be very low, and you still want plenty of smoke, you can increase this value as desired.

Heat

The amount of heat to generate.

Fuel

The fuel used in the simulation. If it is set to zero, there will be no burning.

Curl

The amount of curl in the simulation.

Pressure

The pressure applied to the gas on ignition. The higher this is the more violent the ignition.

Color From

This setting is only used if 'Color' has been checked in the Explosia solver's Solver tab and 'Color' is selected as the display channel. There are three options in the menu:

Object

The colour to use is obtained from the source object, that is, the 'Display Color' colour in the object's Basic tab.

Shader

With this option a shader link field is available. You can add a shader or bitmap to use as the colour to this shader link.

Custom

Selecting this option displays a colour field from which you can select a colour to use.