--- title: "Particle Shader" canonical: "https://documentation.chaos.com/space/PHX4MAYA/125830144/Particle%20Shader" format: markdown --- ## **Overview** --- ## **Particle Systems Parameters** --- > Macro (ui-text-box) > > When using the Phoenix Particle Shader to render Maya's nParticles, add [Per-Particle Attribute Export](https://docs.chaosgroup.com/display/VRAY4MAYA/Particle+Attributes) and Point Size exports from the Attributes → VRay menu of the nParticles Shape node. The Point Size and Age attributes of the nParticles are not exported by default which will cause the Particle Shader's Size controls to function incorrectly. > > > ![image](media://00193f3d-0ffa-4957-a837-4f2aa1f60c14) ## **Rendering** --- > Macro (ui-text-box) > > Note that using this option will override the **Color **parameter. However, using a texture map with the **Color Map** parameter below will override the Use Color From RGB Channel parameter. > Macro (ui-text-box) > > Only **Phoenix Particles** are supported for this option. Also, currently it will only use the **RGB Channel**. In addition, keep in mind that the RGB Channel might not be available in all of the **Particle Systems** that you have selected for your **Particle Shader**. > Macro (ui-text-box) > > Note that when using a **Particle Texture**, its **Particle Area Radius** is very important for the rendering speed - the larger the Particle Area Radius, the slower the render. It's best to start with a very small Particle Area Radius - this way the particles would render with black edges. Keep increasing the Particle Area Radius until the black edges are no longer visible, and this way you would get the best render speed for your setup. > Macro (ui-text-box) > > If using a Phoenix Texture with **Auto Mapping** enabled, make sure that the **Use Liquid Simulator** option is enabled and the **Liquid Simulator field** points to the **Phoenix** container used by the Phoenix Texture. > > For more information on texture mapping in Phoenix, please check the [Texture mapping, moving textures with fire/smoke/liquid, and TexUVW](https://docs-chaos.atlassian.net/wiki/spaces/PHX4MAYA/pages/125832240) page. > Macro (ui-text-box) > > Note that using the Color Map parameter will override the** Color** and the **Use Color From RGB Channel **parameters. > Macro (ui-text-box) > > When rendering nParticles, enable the V-Ray → Per Particle Attribute Export → Age option from the Attributes → V-Ray menu under the nParticle Shape node in the Attribute Editor. ### **Example: Mode** --- --- ### **Liquid Simulator** --- **Liquid Simulator** | *liquid* – Allows a link to the simulator that produced the shaded particles. Currently, only Phoenix objects Fire Smoke Simulator and Liquid Simulator can be set as the Liquid Simulator. When set, the shading of the particles changes when they are inside the liquid volume, as if they are underwater, allowing the use of the Subgroup option. Also, if the simulator uses Displacement, connecting it to the **Particle Shader** will displace the particles as well. > Macro (ui-text-box) > > Note that the viewport preview does not reflect the **Use Ocean Border Fade** option currently. ### **Render Cutter** --- ### > Macro (anchor) **Geometry** --- > Macro (ui-text-box) > > - When** Render as Geometry** is *enabled*, the** Approximate** and **Approximate + Shadows** settings for the** Scattering** parameter are **not supported**. > - When **Render as Geometry** is *disabled*, the Particle Shader is rendered as a volumetric, which is faster, but does not export deep images and many V-Ray render elements such as velocity, multi matte, zdepth, etc. For a complete list of the supported **Render Elements** in both Volumetric and Volumetric Geometry mode, please check the [V-Ray Render Elements Support](https://docs-chaos.atlassian.net/wiki/spaces/PHX4MAYA/pages/125963190) page. > - When **Render as Geometry** is *disabled*, overlapping Particle Shaders would blend correctly, but would not be able to blend together with other volumetric effects such as **VRayEnvironmentFog**, **VRayAerialPerspective**, etc. > Macro (ui-text-box) > > Note that if **Render as Geometry** is *disabled* and you render particles below an ocean surface, you might also need to place a geometry that would serve as a bottom for the ocean. This would be needed only when rendering the ocean with a material that uses fog color. Since the particles and the fog of the material are both volumetric effects and are handled differently than meshed geometry, the volume of the ocean liquid must be closed off with another geometry, such as geometry for the bottom. Otherwise the renderer would not be able to determine if the particles are inside of the fog, or entirely behind it and they might render very dark and cause flickering or other undesirable effects in animation. When** Render as Geometry** is *enabled,* the renderer would be able to correctly render the particles with respect to the fog even without a closing geometry. > Macro (ui-text-box) > > To render particles simulated by Phoenix with Motion Blur, you need to enable the Particle Velocity channel export for each particle system (Foam, Splashes, Mist, Drag, etc.) from the Output → [Output Particles](https://docs.chaosgroup.com/display/PHX3MAYA/Output#Output-OutputParticles) rollout of your Simulator. Otherwise, if rendering particles from other plugins or software packages with Motion Blur, they must have a velocity channel. > Macro (ui-text-box) > > - This option refers to the internal **Phoenix Light Cache**, which is unrelated to the [V-Ray Light Cache](https://docs-chaos.atlassian.net/wiki/spaces/VMAYA/pages/111740744). > - This option is ignored when using V-Ray GPU or Corona. It works with V-Ray CPU. > - When using **V-Ray Progressive Rendering**, the Volume Light Cache option might **slow down** rendering startup or the overall render speed. > - This option might produce **artifacts** when the particles are very dense. > - This option might produce **artifacts** when objects cast shadows through the particles. > - This option will consume additional memory, so beware of high RAM usage when rendering many particles. > - Some V-Ray render elements might not work when Volume Light Cache is enabled. Please consult [this table](https://docs-chaos.atlassian.net/wiki/spaces/PHX4MAYA/pages/125963190). ### **Render Elements** --- ## **Bubbles|Cellular|Splashes** --- > Macro (ui-text-box) > > This rollout is accessible when **Mode** is set to **Bubbles**, **Cellular**, or **Splashes**. > Macro (ui-text-box) > > When using complex lighting with many light sources or dome lights with HDRI maps, increasing the **Light Cache Speedup** option will cause the highlights to jitter over the surfaces of bubbles and this might cause flickering or noise in animation. > Macro (ui-text-box) > > If you get noise and flickering during animation rendering, try disabling **Optimize Congestion** as it will help bubbles to not disappear and re-appear in animation. ### ** Example: Refractive Index** --- > Macro (ui-text-box) > > The image below shows the render differences between **Refractive Index** values of *1.2*, *1.6*, and *3.0*. ### **Example: Glass Geometry** --- ## **Points** --- > Macro (ui-text-box) > > This rollout is accessible when **Mode **is set to **Points**. When rendering in Point mode, changing the Image Output resolution from the Render Settings will affect the appearance of the particles rendered as points. This is due to the fact that points are treated as pixel-sized. If you double the resolution, make sure to double the **Point Alpha** and **Point Radius** settings as well. ### **Example: Point Radius** --- > Macro (ui-text-box) > > The image below shows the render differences between two images rendered at 960x540 vs 1920x1080. The 1080p image is scaled down to 540p to show the difference in the apparent **Point Alpha** and **Point Radius**. ## **Fog** --- > Macro (ui-text-box) > > This rollout is accessible when **Mode **is** **set to **Fog**. > Macro (ui-text-box) > > Decreasing **Fog Voxel Size** by 2x will increase memory usage by 8x. ### Example: Fog Absorption Color --- > Macro (ui-text-box) > > To make the Fog Mode's** Absorption Color** more pronounced when combined with a grey** Color **for the Fog, you’ll generally need to introduce saturation for the absorption, and increase its color HSV brightness value a bit. > Macro (ui-text-box) > > The **Absorption Color** can affect the opacity of the fog as well, depending on how bright or dark its color is. Brighter colors make the volume more transparent, while darker colors make it more opaque (denser). > > Using bright and highly saturated absorption can produce very prominent colors. Introducing color into the Fog's** Color** can create even more striking results. > > Here are some examples showing different Absorption Color and Color combinations. ### **Example: Fog Absorption Color for Mist** ---