Particle Renderer Compound

Density | Particle Color | Volume Color | Volume Rendering | Render Tree Usage

The Particle Renderer compound creates up a basic volume shader setup for ICE particles using the Particle Volume Cloud shader, and some other helper shaders under the hood.

To quickly apply the Particle Renderer shader compound to an ICE point cloud, choose Get Material ICE Particle Volume from the Render toolbar.

This applies the Particle Renderer shader compound to the Volume port on the point cloud's Material node. As well, the Particle Shaper shader compound is plugged into the Density Shape port on the Particle Renderer shader compound.

For general information about ICE particle shaders, see ICE Particle Shading.

Density

Particle

Density Shape	(Textureable Input, per Particle) The texture carves away parts of the particle, starting at its edge. If the input texture is 0.0, the whole particle is gone; if the input is 1.0, nothing is carved away. With the Intensity slider, you can scale the intensity of the input texture.
Density Limit	(Textureable Input, per Cloud or Gradient) Sets the maximum allowed density for the particle cloud (reduce this value for steam or thin smoke). If the value is high, the particle cloud shrinks if you reduce the density. In the real world, steam particles are evenly spread in space; however, in 3D, you often have a higher density of particles in the inner parts of the volume and less density in the outer region. If you now reduce the density, the particle cloud seems to shrink because you don't see the outer region, but the inner region still has enough density to be visible. With this parameter, you can limit the density in the inner part of the cloud. If you now reduce the density of the whole volume, your cloud does not appear to shrink.
Falloff Type	Type of the shape falloff: Linear or Cubic. Cubic is better for dense volumes, and Linear is better for thin volumes.
Metaball-like Shape	If you increase this value, the whole particle cloud shrinks and the particles melt together (like metaballs). The metaball look is more evident if you have dense volumes.
Elliptical Shape	Elongates the density shape of the particle along its Y axis.

Volume Density

Global Density

The density of the whole particle volume. The global density is multiplied with the input Density Shape.

This sets the overall effect of the density on the particle, with the center of the particle being more opaque than its edges.

Low density values give softer, smoother effects (more transparency) while higher density values create more well-defined details and edges (more opacity).

Shadow Adjust

Fine-tunes the density of the volume according to the shadow rays.

Particle Color

Per Particle: Color

Color

(Textureable Input, per Particle) The color of the particles using the input shader's color.

Override Particle Color

Overrides the color of the particles using the color you set with the color sliders here.

You cannot use this option if there is a shader plugged into the Color port.

Per Cloud or Gradient: Color/Density

Enable Global/Gradient Color inputs

Uses the input shaders that are plugged into the Global Gradient Color and Global Gradient Density ports.

Global Gradient Color

(Textureable Input, per Cloud or Gradient) Changes the color of the whole cloud, which overrides the Per Particle: Color settings.

Global Gradient Density

(Textureable Input, per Cloud or Gradient) Changes the density for the whole cloud. The cloud density is multiplied with the input density.

You can use the same gradient shader that you have used for the Global Gradient Color input.

Volume Color

Ambience

Tint Ambient Color	Adjusts the ambient color of the whole particle volume.
Ambience Intensity	Intensity of the ambient shading.

Diffuse

Enable Illumination	Enables the illumination for the whole particle volume.
Tint Diffuse Color	Adjusts the diffuse color of the volume.
Diffuse Intensity	Intensity of the diffuse shading
Use Particle Color for Diffuse Illumination	The diffuse color is based on the particle color. If this option is off, the diffuse color is based only on the Tint Diffuse Color setting.

Ambient Occlusion

See Ambient Occlusion for more information.

Enable Ambient Occlusion	Calculates simple Ambient Occlusion (AO). The Ambient Occlusion is calculated for the lookup table. It does not take any normal direction into account.
Intensity	Modifies the intensity of the AO calculation.
AO Color	Color of the ambient occlusion.

Volume Rendering

Marching

For information on marching steps, see Marching.

Detail

Presets for the marching step settings. Low Settings render in about 60% of the Default Settings' time. With High Settings, the volume takes twice the render time as the Default Setting time.

Shadow Table

For an explanation of the lookup table, see Lookup Table.

Interpolation	Interpolation between the cells in the lookup table — see Particle Volume Cloud for information. None: No blending is done between the table cells. This is fast and should be used only to tweak the table size because you can see the voxels (cells).
Linear: Simple interpolation (default) between the cells.
Cubic: More complex calculation used for interpolation between the cells. Use this option if you can still see the rows of the lookup table, but you already have enough table resolution to catch all shadows.
	Full Light Raytrace: This option is the slowest. Use it for very dense volumes with a very small edge falloff, such as volumes that have too much shadow detail for a lookup table. You need to set a cell size because the lookup table is used not only for shadows. The lookup table should cover the average shape of the volume.
Cell Size	Sets the size of the cells in the lookup table.
Memory Limit (MB)	While you are tuning the shader, you will probably reach the memory limit. This setting catches this case and prevents mental ray from stopping the rendering. It renders the volume with lower settings and in a red color. For tips about reducing the memory used, see Memory Limit.
Enable Fast Preview for Region	With this option on, you can easily switch the total render times by influencing the lookup table and ray length. You can also render the lookup table for tuning or render the volume in slices to check a texture. For more information, see Preview.

Render Tree Usage

Plug the Particle Renderer output into the Volume port of the Material node. You can also plug other shaders into it, such as the Fractal Scalar or Cell Scalar shader for adding noise to each particle density's shape, or the Particle Gradient shader or Particle Gradient Fcurve compound to define the color and density using gradients.

Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License