Type – Sets the shading mode: Bubbles – Each particle is shaded as a spherical, transparent, reflective foam bubble. Surfaces of bubbles that intersect one another are visible inside the bubbles. If you get flickering or noisy renders of tightly packed masses of foam such as beer heads, you should switch to Cellular mode. Otherwise, in animation, pairs of bubbles would appear with one bubble completely in front of another in one frame, and completely behind on the next frame, once the bubble's center goes behind the other bubble's center. This would cause abrupt changes in the overall look of the foam mass in animation. Cellular – Similar to Bubble mode, but replaces intersecting walls between bubbles with a curved wall. This mode is about twice as slow as simple Bubbles but is suitable for close-up foam. Splashes – Each particle is shaded as a spherical, opaque, reflective droplet. Surfaces of droplets that intersect one another are not visible. Note that when a Liquid Simulator is connected, particles do not render as Splashes when they are inside the liquid volume of the Liquid Simulator. This is because Splashes represents small liquid droplets used to add more detail to the Liquid mesh, so it does not make sense to render them underwater. Points – Particles are shaded as flat discs, each the size of one pixel by default. This mode is faster than Bubbles, Cellular, and Splashes and thus is suitable for large scale foam and splashes over a large surface such as an ocean surface. This mode is also suitable for rendering non-foamy fluids such as smoke or ink. Because the points are pixel sized, moving the camera away or decreasing the render resolution makes them appear denser, while moving the camera in closer or increasing the render resolution makes the particles look more scattered. Note that Point mode does not do reflections or refractions like the Bubbles, Cellular, and Splashes, so the particles look diffuse and sometimes darker if you render them next to strongly reflective materials. Count Multiplier – Increases or decreases the number of particles for rendering. When the value is below 1, the particle count decreases, skipping the particles randomly. When the value is above 1, new particles are created and placed randomly among the original ones in a way that attempts to preserve the group's overall shape. Note that you have to export the particle ID channel if you want to render animation, otherwise the particles would start appearing and disappearing in different places during the animation. ColorFoam Color – Specifies the particle color. Diffuse Multiplier – Provides an additional option to multiply the color brightness. Bubbles|Cellular|SplashesRefraction Index – The IOR of the bubble material. Higher refractive indices produce more pronounced reflection and refraction. Bounces – Specifies the maximum depth of reflection/refraction branches. When the limit is reached, the color of the Environment texture is used instead of starting new rays. Using more bounces slows down the rendering considerably, but reduces any flickering that may appear with a higher Refractive Index. Reflection Cut Off – Starting a reflection ray is an expensive operation because it produces an avalanche of rays that can consume resources very quickly. Because of this, a reflection ray is only started if its result is very visible. This parameter is used to determine the critical visibility at which new reflection rays will start. If the visibility is less than the specified value, the Environment map is used instead of tracing a new ray. This option has no effect if the Bounces are 0. Highlights Width – Specifies the width of the specular highlights. Highlights Strength – Specifies a multiplier to control the brightness of the highlights. Pressure Variation – Used when Type is set to Cellular, which produces a wall between each two bubbles in contact. In nature, no two bubbles in contact have exactly the same internal pressure, and the bubble with the higher pressure pushes against the lower-pressure bubble to produce a curved wall between the two. In the simulation, a random pressure difference is assigned to bubbles in contact, with the Pressure Variation value as the maximum. Larger values result in a more pronounced curve between the bubbles. Optimize Congestion – When the particles overlap significantly in tight bunches such as beer head simulations, the render speed may drop significantly. With this option, an optimization pre-process is performed that deletes the bubbles that are fully inside other bubbles, and decreases the sizes of significantly overlapped bubbles. This reduces render times with a minimal impact on quality. Enabling this option is highly recommended. TexturesOverride Reflections – Enables reflection map. Reflection Coloring – Used to represent the coloring of the bubble reflection due to interference. The texture is sampled using the direction instead of the explicit coordinates. Override Environment – Enables environment map. Environment – This map is used when the visibility is less than the Reflection Cut Off value or when the renderer's reflection depth is reached. The texture is sampled using the direction instead of the explicit coordinates. PointsIgnore Particle Size – By default, the point shader calculates the alpha by considering the size of the particle and the distance to it. This option is used when the particle system contains particles that are too large and leave hard tracks with motion blur. Motion Blur Step – Unlike the Bubbles, Cellular, and Splashes modes, motion blur in Point mode is calculated by cloning the particle several times and placing the copies along the trajectory. This parameter controls the distance between the copies. The smaller the step, the higher the quality, though at the cost of render time. Motion Blur Limit – If the particle system contains very fast particles, or if the motion blur step is too small, there is a possibility of rendering overload due to the huge count of particle copies. This parameter sets a limit on the number of clones to keep a reasonable rendering time. |