What's New in Fluid Effects

Auto Resize

Maya Fluid Effects now includes an Auto Resize feature. Auto Resize dynamically resizes 2D and 3D fluid containers when the density near the edges of the fluid reaches the set Auto Resize Threshold value. With Auto Resize on, Maya allows the container to only extend to regions with density, rather than keeping the fixed resolution and offset that the grid started out with. The smaller simulation region increases simulation speed, reduces rendered times, uses less memory, and results in smaller fluid cache files.

Auto Resize works well with fluid effects that move, such as a missile vapor trail or the rolling smoke of an explosion, as it keeps the fluid container relatively small.

Watch: Fluids Auto Resize

Self Attraction and Repulsion

Fluid Effects now includes Self Attraction and Repulsion attributes that generate attractive and repulsive forces between the voxels in 2D and 3D fluid containers. Using Self Attraction and Repulsion attributes, you can specify whether the forces use density or temperature grid values as well as control the strength of the attraction and repulsion force.

You can use Self Attraction and Repulsion to create effects such as swirling gas clouds and galaxies that contract and expand. Using a strong self repulsion force, you can simulate rapidly expanding gases to create the look of realistic explosion flashes.

New Dynamic Simulation attributes

New Dynamic Simulation attributes improve the quality of fluid simulations.

The new attributes include the following:

Forward Advection

Forward Advection is a new method that you can use for calculating Density, Temperature, and Fuel grids. When on, these grids are solved using a mass conserving forward propagation technique that pushes density forward through the grid. Fluid effects solved using Forward Advection can produce fewer artifacts when the High Detail Solve option is used, and results in less diffusion than the default solve method. Forward Advection can also resolve instances where density remains static in voxels.


Use Substeps to specify the number of times the solver performs calculations per frame. Substeps are useful for improving the stability and simulation results of fast-moving fluids, fluids with high density grids, and when the High Detail Solve option is used.

Output mesh per-vertex shading attributes

You can now generate per-vertex color, opacity, and incandescence data when you convert your fluid object to a polygon mesh. When on, Color Per Vertex, Opacity Per Vertex, and Incandescence Per Vertex generate per-vertex data which is derived from the fluid object's color, opacity, and incandescence values. The output mesh per-vertex data is color set data that can be applied to the polygon object like other color set data.

Velocity Per Vertex for motion blur

You can now create motion blur when you render fluid output meshes. A new Velocity Per Vertex attribute generates velocity per vertex data when a fluid object is converted to an output mesh. When you render your fluid output mesh using mental ray for Maya, velocity per-vertex data generates motion blur in the rendered output.

Uvw Per Vertex

You can now generate a UVW coordinate system for your fluid output meshes. A new Uvw Per Vertex attribute outputs UVW coordinates when a fluid object is converted to an output mesh. You can use the Uvw per-vertex data to assign textures to fluid output meshes.

You can use the UV Texture Editor to modify the output mesh UVs like any other polygon surface.

Fluids Lighting

A number of new Lighting attributes have been added to Fluid Effects that let you preview the lighting and shadowing of your fluid in the workspace before rendering. There are now more internal lights, including point, directional, and ambient lights, that you can use to light your fluid effect. Using internal lighting decreases fluid render times. See Lighting fluids with internal lights.

Watch: New Fluids internal lighting attributes

New fluid lighting features include the following attributes:

Shadow Diffusion

Controls the softness of the fluid's internal shadow, simulating local light scattering. Shadow Diffusion can only be seen in the workspace not in a rendered fluid. To use Shadow Diffusion effects in your finalized fluid, you can use Playblast to output simulated frames.

Light Type

Use Light Type to select the type of internal light you want to use with the fluid when displaying it in the workspace. You can now select an internal diagonal, directional, or point light. If Real Lights is off, the selected internal light is used to light the fluid for rendering.

The internal point light also includes a Point Light Decay attributes that let you control how quickly the light's intensity decreases with distance.

Light Brightness and Light Color

You can use Light Brightness and Light Color to set the intensity and color of the selected internal light. Light Brightness and Light Color are similar to the intensity and color attributes that are used with scene lights.

Ambient lighting

Fluid Effects now includes ambient lighting which you can preview in the workspace before rendering. Using ambient light attributes, you can control the intensity, color, and diffusion of the ambient light.

New Dynamic Simulation attributes

New Contents Details attributes let you add more detail and turbulence to your fluid effects.

These new attributes include the following:


Density, Temperature, and Velocity now include a Noise attribute that randomizes density, temperature, and velocity grid values. You can use Noise to create turbulence as well as to add detail to a fluid effect.


Density and Temperature now include a Tension attribute that lets you smooth ranges of density and temperature into round shapes, making the density and temperature boundaries more defined in the fluid. You can use Tension to create effects that are similar to the effect of surface tension in liquids.

Gradient Force

Density now includes a Gradient Force attribute that applies attractive and repulsive forces along the direction of the density gradient. Positive Gradient Force values push in the direction of increasing density, producing an attractive force. Negative values push density away from itself, producing a repelling force.

Gradient Force is similar to Self Attraction and Repulsion, but the effect of Gradient Force is localized to the adjacent voxels and takes less time to calculate than Self Attraction and Repulsion.

Boundary Draw improvements

The Outline option for the Boundary Draw attribute has been improved on 2D fluid containers. A dotted line displayed around the container indicates the potential volume of the 2D fluid.

Emit fluids from nParticles

You can now emit fluid from nParticle objects using Emit from Object. To control the fluid emission rate, you can either use fluid emitter attributes, or you can use nParticle per-particle rate and per-particle radius attributes.

For example, you can use a per-particle ramp or an expression to control the radius of fluid emission based on the per-particle radius of nParticles. You can also emit fluid from Maya classic particles.

Emitting fluid from nParticles lets you combine fluid and nParticle effects in the same simulation. This provides better control over smoke, fire, dust, or debris clouds that result from nParticle collisions and explosions.

New fluid emitter attributes

Maya 2011 includes the following new fluid emitter attributes:

Rate (Percent)

A new Rate (Percent) attributes lets you scale the individual emission rates of all fluid grids, including Density, Heat, and Fuel with one attribute. Rate (Percent) sets fluid emission rate as a percent.

Emission method

New emission methods for Density, Heat, and Fuel let you specify how contents are emitted into fluids. The default Add method adds contents using a continuous emission rate. This is the same emission method used by fluids in previous versions of Maya.

A new Replace emission method lets you specify the total amount of contents emitted in the fluid. It can be used to obtain specific amounts of density, heat, and fuel without needing to reset the fluid’s initial state from an advanced frame. This is useful for quickly simulating effects such as rising heat and wind tunnels.

Emission maps

There are now emission maps for Density, Heat, and Fuel. Using the emission map attributes, you can map a 2D texture to control emitted density, temperature, and fuel. Texturing the emission is now supported.

Motion Streak

When on, Motion Streak smooths emission stamps into a continuous fluid streak. Motion Streak is most useful for effects with fast moving emitters, which can cause emission stamping.

Keep Voxels Square

Use Keep Voxels Square to set a fluid container's resolution based on the fluid Resolution and Size values while maintaining square voxels in the local space of the fluid. Square voxels can provide better fluid simulation and rendering results.

When Auto Resize is on, voxels are kept square by default.

Base Resolution

When Keep Voxels Square is on, you can use Base Resolution to simultaneously set the X, Y, and Z Resolution values of your fluid container.

Texture Rotate

A new Texture Rotate attribute lets you rotate the fluid's built-in texture.

Normalized Dropoff

A new Normalized Dropoff attribute for volume emitters is now fixed relative to the emitter’s scale, rather than to Worldspace. This ensures that fluid simulations remain consistent if the fluid container and emitter are scaled together. It also improves Fluid Dropoff for Cube volume emitters by using a smooth dropoff towards the volume boundaries. In previous versions of Maya, a cylindrical shaped dropoff is used with Cube volume emitters.

Use Distance

A new Use Distance attribute lets you use Min Distance and Max Distance with Surface and Curve emitters. In previous versions of Maya, to use Min Distance and Max Distance with Surface and Curve emitters, Min Distance has to be set to a value other than 0. You can now set Min Distance to 0 for Surface and Curve emitters.

Emission Speed Attributes

A number of new Emission Speed Attributes let you control speed and velocity emission for all emitter types. For example, you can adjust emitted speed along the tangent of a Curve emitter or along the axis of a Volume emitter.

High Quality Solve improvements

Fluid simulations solved with the High Quality Solve option are now more stable and have fewer artifacts when Forward Advection and Substeps are used.