Emission
This option is used to enable or disable the Liquid FX Emitter. Only when it is enabled will spray, foam, and bubble particles be created from the liquid particles. Animating this option can be used, for example, to start and stop the emission individually.
The new particles are distributed randomly around their source particles. This value forms the basis for this random calculation. A change in the Seed value therefore leads to a different distribution of the particles, but does not change their number. Random variations, such as the Variance of the Age Threshold, also use this Seed value.
This value acts as a multiplier for the number of emitted particles. The number of spray, foam, and bubble particles changes in direct proportion to this value: Doubling the Resolution doubles the number of particles of all three types. This makes it the easiest way to control the overall amount of Liquid FX particles. The size and color of the particles are defined separately on the Properties tab.
Tip: Work with a low Resolution while you adjust the other settings, and increase it only for the final simulation.
Defines how widely the new particles are distributed around their source particle. At 100 %, the new particles fill the cylindrical space that the source particle sweeps with its radius while it moves. Lower values keep the new particles closer to the path of the source particle, higher values distribute them over a larger area. The number of particles is hardly affected by this setting. With very high values, spray and foam particles spread noticeably further, while bubbles remain close to their source particle.
The settings in this group determine which particles of the liquid simulation can act as a source for new spray, foam, and bubble particles. A liquid particle must meet the requirements for age, speed, and number of neighbors in order to emit new particles. The Liquid FX Emitter evaluates all liquid particles within its simulation scene. By default, this is the entire Cinema 4D scene. If you use separate Simulation Scene objects, the emitter only takes into account the liquid particles within its own simulation scene.
Minimum age a liquid particle must have to qualify as a source. This prevents spray, foam, and bubbles from being created directly at a liquid emitter, where the newly created liquid particles are still very young. At a value of 0, freshly emitted liquid particles can also act as a source, which can considerably increase the number of Liquid FX particles.
Use this value to randomly vary the Age Threshold per particle. The required age can deviate from the Age Threshold by up to the entered value. Like all variation values, this setting is based on the Seed value of the emitter.
Minimum speed a liquid particle must have to emit new particles. The value is a speed in centimeters per second. Calm areas of the liquid therefore remain free of spray, foam, and bubbles. Higher values restrict the emission to the fastest parts of the liquid and reduce the number of Liquid FX particles.
Above the Speed Threshold, the number of emitted particles is linearly interpolated over this range of speeds: It increases from the Speed Threshold until the full amount is reached at the Speed Threshold plus Speed Range. A larger value therefore results in a softer transition between areas with and without emission.
Neighbors Threshold[0..2147483647]
Minimum number of neighboring liquid particles a liquid particle needs in order to emit new particles. Higher values reduce the number of all three particle types and shift the mix from foam toward bubbles. Lower values result in noticeably more spray and foam, while the number of bubbles increases only slightly.
Neighbors Range[0..2147483647]
Above the Neighbors Threshold, the emission is scaled over this number of neighbors until it reaches its full amount. Larger values result in a flatter transition and therefore in fewer particles. Below a certain value, reducing the range further has hardly any effect.
Trapped Air describes how much air is trapped in the liquid. This value is estimated for each liquid particle from the velocities of the neighboring particles and their impact against each other. The settings in this group control how many particles are emitted depending on this value. In calm liquids, trapped air mainly produces bubbles, which turn into foam when they reach the surface. In fast-moving liquids, it can also produce a lot of spray and foam.
Minimum Trapped Air value at which particles are emitted. Liquid particles with a lower value do not emit. Note that in calm liquids, the Trapped Air value can remain below the default value of 1 everywhere, so that no particles are created from this source at all. In this case, lower the Threshold step by step until particles appear.
Above the Threshold, the emission increases linearly over this range of Trapped Air values until it reaches the full Rate. A smaller value reaches the full Rate sooner and therefore creates more particles.
Defines the number of particles emitted from trapped air at full strength. The number of particles changes in direct proportion to this value, so doubling the Rate doubles the number of particles from this source. In addition, the result is multiplied by the Resolution value.
Wave Crest is an estimation of the local curvature of the liquid surface. The settings in this group control how many particles are emitted depending on this value. In many scenes, wave crests are the main source of Liquid FX particles, and these settings change the number of spray, foam, and bubble particles to a similar extent.
Minimum Wave Crest value at which particles are emitted. Liquid particles at less curved areas of the surface do not emit. Lower values allow weaker wave crests to emit particles as well.
Above the Threshold, the emission increases linearly over this range of Wave Crest values until it reaches the full Rate. A smaller value reaches the full Rate sooner and therefore creates more particles.
Defines the number of particles emitted from wave crests at full strength. The number of particles changes in direct proportion to this value, so doubling the Rate doubles the number of particles from this source. In addition, the result is multiplied by the Resolution value.
Here you can link the Particle Groups in which the spray, foam, and bubble particles are managed. When you create a Liquid FX Emitter, three groups are created automatically and linked here. By default, existing groups are reused if you create further Liquid FX Emitters or Liquid FX Modifiers.
Note that a particle does not keep its type permanently. It switches automatically between the three groups depending on the number of liquid particles surrounding it: A low number of neighbors turns it into spray, a high number into a bubble, and values in between into foam. The exact values for this can be set on the Liquid tab of the Simulation Scene object. For example, spray that falls back into the liquid turns into foam or bubbles, and bubbles that rise to the surface turn into foam.
The Particle Group in which the spray particles are managed. Spray particles have only a few liquid neighbors, for example drops that fly through the air. Simply drag a different Particle Group from the Object Manager into this field or click on the pipette symbol next to the field and then on a Particle Group in the Object Manager.
The Particle Group in which the foam particles are managed. Foam particles float on the surface of the liquid. You can link a different group here in the same way as for the Spray Group.
The Particle Group in which the bubbles are managed. Bubbles are located inside the liquid and rise to the surface. You can link a different group here in the same way as for the Spray Group.
Clicking this button creates three new Particle Groups for spray, foam, and bubbles and automatically links them to the fields above, even if other groups are already linked there. This allows you, for example, to manage the particles of several Liquid FX Emitters in separate groups.