Fluid Effects limitations

If you have old fluids from 7.0.1 or earlier that use temperature turbulence, their simulations will play back differently each time they are played due to the backward compatibility settings.

If you don't want to keep this random behavior, run the following MEL script for each fluidShape that uses temperature turbulence:

Fluid Cache creation uses the current state as the starting point

When creating a cache for a fluid, the current state of the fluid will be used as the starting point for the cache.

If you do not wish to use the current state, but want to start again from the initial state of the fluid, rewind to the fluid start frame. If the start frame for the fluid is not the same as the cache start frame, run the fluid up to the start frame of the cache.

Like-named fluids cause cache problems

If you have a scene that contains 2 or more fluids, and their fluidShape nodes have the same name, then fluid caching will not work correctly for those fluids.

Make sure that the fluid nodes in your scene have unique names if you intend to cache them.

MR render does not read fluid names properly

Ensure that each fluid shape in your scene has a unique name; when duplicating a fluid, make sure that Assign Unique Name is turned on.

Fluid texture not updating

A fluid texture does not update if not connected on outColor. When rendering in mental ray if the fluid is only connected on outAlpha, it does no t update.

Surface shaded 3D fluid with Opacity Texture looks different in software render

If the dropoff shape is off, or the edge dropoff is 0, and your 3D fluid has density (greater than the surface threshold) in the boundary voxels, you won't see an outside boundary in hardware draw.

If you need to see the outside boundary in the hardware draw, set the dropoff shape to cube, and the edge dropoff to .01.

2D texture collision missing some areas

Fluid object doesn't render in the exported file

If you exported a fluid with inputs off, you may end up losing the fluid shading connection to itself, and the fluid will not render.

Fluids cache nodes may be named incorrectly

If you create a cache or initial state for a referenced fluid or a fluid in a namespace, the cache nodes will be named incorrectly. For example, if you create a cache for fluffy:fluidShape1, the cache node may be named fluidShape1.

Rename the cache node to initialState_fluidShape1 or cache_fluidShape1 as appropriate.

Referenced file initial state cache may be modifiable from parent file

If your referenced file has an initial state cache, you can modify it from the parent file.

Don’t modify it—either by painting or save initial state (unless you really mean to).

Floating object animation limitation

Look at the extra attributes on the associated locator shape, and modify to compensate for the change of units. The scene scale is normally used to match the ocean shader scale, but it can also be used to compensate for the units relative to centimeters. Or you can modify gravity, or some of the other physical constants to get the desired motion in your units.

Alpha in image plane expands when used with volume fluids

Set the colorGain to zero and the color offset to 1 in the image plane.
On the fluid node set the Color ramp to all black and then set the Incandescence ramp to white.

Different blending cutoff in attribute presets for multis than strings, enums

If you apply an attribute preset with blending for a node that has ramp attributes and there isn’t a one-for-one match between the entries on the corresponding ramps, you may get unexpected results. If these results are not satisfactory, you may have to adjust the results by hand. If you undo this kind of blend, you may end up with an extra index entry with a position and value 0. If so, delete the extra entry.

Ocean Shader: How do you create a tiling looping texture from it?

Here is a more detailed recipe for looping an ocean:
LOOP_FRAMES = number for frames after which animation repeats.

Create an ocean or ocean shader. Set the numFrequencies and waveHeight both to zero so that the ocean is totally flat and more optimal to render.
Map the oceanShader waveHeightOffset with an ocean texture..asProjection = ON and newTexturePlacement OFF. On the projection set the rotateX to 90.
Map the colorOffset of this texture with another ocean texture.. asProjection = OFF and newTexturePlacement = OFF
Animate the time values of the two ocean textures such that the start of one is the same as the end of the other.

Keyframe the waveHeight on the two textures to do a cross dissolve:

The ocean animation should now loop across the number of frames specified by LOOP_FRAMES above. For it to work the two ocean textures must have identical values (apart from the wave height and time). With this method you cannot preview the displacement of the ocean using the heightfield node (convert displacement to poly will work). Also buoys and boats will not animate with wave height (texturing on the ocean shader is currently not taken into account for these effects).

Volume light Emit Ambient attribute not updating in IPR

Multiple processors for fluid rendering may result in artifacts

When using four or more processors for fluid rendering, you may experience artifacts.

Multiple processors for fluid rendering may result in system crash

When using a multi-processor/multi-core machine for fluid rendering, you may experience crashes.

Texture does not return to its original position

If your Texture Coordinate Method is set to grid and you are painting your fluid with autosave on, the texture does not return to its original position.

Rewind, change coordinate method to fixed then back to grid again. Avoid saving unwanted grids, make sure that your saveInitialState options are set to indicate which grids should be saved.

Unexpected results when self shadowing on a surface rendered fluid

When self shadowing on a surface rendered fluid, you may get unexpected dark regions and artifacts.

This only happens if the fluid has no transparency. Increase the quality until the artifacts disappear. Alternately, set the transparency to a non-zero value and it behaves as expected.

Hardware display issues with Node Caching

When Node Caching is turned on, you may get unexpected results in the hardware display.

Don't turn on Node Caching for Fluid Effects. If you did, turn it off, save your file, and restart Autodesk® Maya®.

Depth buffer inaccurate for surface fluid

When rendering a fluid with depth output and a surface style fluid, you would expect the surface to appear correctly in the depth buffer, especially if the fluid surface transparency is zero. By default nothing will appear in the depth buffer. You must set the camera depthType to the closest visible depth to see the fluid in the depth output. However the depth value will be the near intersect with the fluid bounds, rather than the actual depth of the blobby surface. This could create problems for composites with objects (or paint effects) within the fluid bounds.

You can get closer to the correct depth by enabling volumeSamplesOverride and increasing the volume samples on the fluidShape. Note this may create artifacts with surface type fluids and it will take longer to render.

Fluid wireframe draw (particles) does not work if voxels too small

If the voxel resolution is set low, nothing appears in the Fluid wireframe draw (particles).

Can't create partial presets if node has multi attributes

You may want to edit the preset file so that it only contains a subset of the node's attributes, but when applying a preset to a node with multi attributes, it empties out all the multis first, and then adds entries to the multis from the preset. Do not alter these files, particularly the entries for any multi attribute, such as ramps.

Convert Fluid to polygon full of holes with smooth interpolation

When converting a Fluid to a polygon with smooth interpolation, you will most likely get holes in the mesh.

Use linear interpolation and then average the vertices, or, with smooth interpolations, using fillHole will deal with these holes except when the boundary has non-manifold vertices. In this case we recommend increasing the threshold until the geometry is no longer non-manifold.

Surface rendered 2d fluid image is not consistent with Render As display

The drop off shape for the cone (and double cone) isn't capped, so you still end up with the ends open. This is intentional.
In a 2D fluid, not enough triangles are generated along the depth, so in a deep 2D fluid, the sphere will look like a cylinder and the cone will look like 2 cylinders.
You will get ribboning if your drop off shape is off, or the edge dropoff is 0, whatever the shape.

Noise and volumetric objects

Older presets are not removed when Maya uninstalled

Uninstalling Maya does not remove the presets folder (in case you have added your own presets to it). So if you have previously installed an older version of Maya (for example, if you are a beta site), some old presets which no longer work correctly may remain in your new install.

Manually remove the presets folder or just the unwanted presets from your install location before re-installing Maya.