Blob Sample

The sprite item provides useful functionality when using bitmap images to generate volume-like effects that render much more quickly than standard volume effects.

Adding Sprites

You can add a Sprite item in the Items list by clicking Add Item > Volumes, then double-clicking Sprite. Once added, the item appears at the bottom of the Items list. When selected, a number of attributes controlling the sprite item's appearance appear in the Properties Panel, this is where you specify the actual sprite texture and point source options.

Applying Materials

Normally, surfaces are applied using polygon tags that define masks in the Shader Tree, controlling material placement. However, sprites are procedural constructs created at render time and have no selectable polygons to apply a tag to, so surfacing is applied to the sprite item through the use of an item mask. You can quickly create an item mask by right-clicking on the sprite item in the Items list and choosing the Create Item Mask option from the contextual menu. You can then add materials and other Shader Tree items, setting the appropriate effect for each layer building up surfacing attributes just as you would for any other surface. The material's Volumetric Scattering and Absorption options are the main controlling factors in its appearance. You can also control additional attributes of the Particle Source that are not surface specific, this can be done by creating an additional item mask and applying texture layers set to the appropriate effect using the FX item of the Shader Tree. For more on using FX, see FX Item.

Blob Properties




Displays the current item name. You can change it by clicking on the field and typing the new name.



An item transform that allows you to numerically position the item in XYZ space. By default, Position transforms originate from the center position.


An item transform that allows you to numerically set the rotation of the item. By default, Rotation transforms originate from the center position.


Allows you to set the order that rotations are applied to the camera item. Changing the order that rotations are applied can sometimes help to reduce or eliminate gimbal lock.


An item transform that allows you to numerically set the size of the item. By default, scale transforms originate from the center position.


Resets the selected transform values to (0,0,0) returning the items to their default state.


Resets the chosen transform property values to 0, leaving the center position and mesh position intact.


Transform items are the channel groups associated with an item that store its transform values, controlling its position, rotation and/or scale. By default, new items do not have any transform items associated with them (even though they are visible here within the Properties panel). This is useful as an optimization as only the necessary transforms are added on an as-needed basis, reducing scene overhead. There are several ways to add them. One is by simply transforming the target item with one of the various transform tools (or by editing the values' input fields). This action causes the particular transform item to be added automatically to the Channels viewport list. The Add function here can also be used to add the selected set of transforms to the Channel list while keeping the default 0,0,0 values (a necessary step for referencing, in order to override the channels, they must first exist).


GL Display

Toggles the display of the sprite proxy in the 3D OpenGL viewport. Generally, this should be enabled to get an approximation of how the sprite particles render (the default state), but in heavy scenes it may be useful to disable this option to increase scene interactivity.

Particle Source

When a sprite item is created, it is represented by a single locator-type point at the World Origin, producing a single sprite image. To produce additional sprites or sprites as a volume, you need to define a particle source, which can be any item layer that contains vertices, where each vertex position is used to determine the position of the sprite particle (any type of geometry can be used- single point polygons, vertices, two-point polygons and regular polygons, however, only the vertex positions of any component are used). Source layers can be normal geometric forms, point clouds that are imported or created using the particle cloud item or any of the particle tools. They can be imported particle simulations controlled by way of a MDD deformer, RealFlow point cache or an Alembic format data file.


Specifies the base size of the blob. From here, the size can be altered with the Random Size option, the addition of a particle size Vertex Map that allows you to paint the scale for individual particles interactively, or with the application of a texture layer, under the FX item of the Shader Tree, set to control Particle Size.

Random Size

Controls the amount of randomness added to the scale of each individual particle sprite. The amount is determined by a scale percentage - a setting of 25% adjusts the scale of the base radius size by an amount of 0%-25% randomly across all particles, a setting of 50% adjusts the size by 0%-50% randomly across all particles and so on.

Position Offset

Adds an offset to the sprite position along the particle normal direction. This is mostly useful for surface particles when you want to detach them from the surface they originate from.

Use Particle Orientations

Aligns the particle to the direction vector from the particle source. The direction vector is usually the surface normal for surface particles or the particle velocity vector for simulation particles (like from RealFlow).

Align to Path

Aligns the particle to its local motion vector.

Automatic Texture Offset

Adds an offset to the hypertexture different for each particle so that each particle looks different.


Sprite Image

Determines the image used for the sprite particle. Load an image into the Image List to select it here. Multiple images may also be used when defined as a group. For more on creating groups, see the Groups Viewport topic.

Luminosity as Density

When enabled, the luminosity of the image is used to determine the density of individual sprite particles.


When enabled, the assigned sprite image acts like individual single polygons with the image mapped to the surface that always face toward the camera.

Note:  Under Shading, set Density to 100% and Falloff to 0% for the full image effect.



Specifies the thickness of the individual sprite particles, controlling the apparent amount of particular matter that is visible in the overall volume.


Specifies the attenuation of the individual sprite particles from their center point out toward their edges.


Changes the level in the hypertexture.

Hypertexture Amplitude

Determines the amplitude (intensity) of a volume density texture layer applied to the sprite volume. The higher the value the more you see the effect of the density texture. It's similar in concept to displacement amplitude, but applies to volumes.

Hypertexture Scale

Changes the size of the hypertexture, it is the same things as changing the texture locator scale settings.

Texture Effect

Hypertextures can be animated on particles to create billowing or dissipation effects. The goal of these effects is to add secondary animation to the particles, which is important for explosions and smoke. The various texture effects are:

None: Disables the texture effect.

Velocity Translate: Moves the texture in the direction of the velocity vector.

Expand: The texture is scaled over time to give the impression that it expands.

Expand and Dissolve: Like the previous effect, but with the addition of a dissolve effect so as the texture expands it also dissolves.

Pyroclastic: A boiling motion where hot gas swirls around within the form adding a realistic secondary motion to the volume. Good for smoke.

Effect Speed

Controls the speed at which the texture effect animates.


The overall scattering amount on the sprite volume, this is similar to the volume scattering amount in the material.