> For the complete documentation index, see [llms.txt](https://shaheerxansari.gitbook.io/hydroportdoc/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://shaheerxansari.gitbook.io/hydroportdoc/cache-preparation.md).

# Cache Preparation

HydroPort is optimized for **baked, deforming fluid polygon meshes**, not for transforming groups of static objects.

## Required characteristics

* One Alembic (.abc) polygon mesh to read as the animated surface.
* Mesh positions that deform across samples; topology-changing liquid surfaces are supported.
* Valid triangulated faces, positions, and sample data.
* Optional UVs, normals, and velocity information for shading and motion blur.

## Unsupported content

* Multiple independent Alembic polygon meshes in one cache.
* Transform-only animation as a general asset animation system.
* Crowd/instance/point-cloud data as a substitute for deforming polygon mesh samples.
* Animated collision on the fluid surface.

## Velocity considerations

For cinematic motion blur, prefer an Alembic export containing usable per-vertex velocity vectors. Make sure the velocity values and units match the import settings. A mesh that animates successfully may still have insufficient or incorrectly scaled velocity data for good deformation motion blur.

## Scale and orientation

HydroPort's internal conventions are Unreal **centimeters** and **centimeters/second**. Houdini/Blender presets assume meter-scale workflows; Maya assumes centimeter-scale by default. Always check the conventions of your particular source file before importing.

## Export checklist

{% stepper %}
{% step %}

### Bake the fluid mesh simulation

Bake the fluid mesh simulation in your DCC/simulation package.
{% endstep %}

{% step %}

### Export one deforming Alembic polygon mesh

Export **one deforming Alembic polygon mesh**.
{% endstep %}

{% step %}

### Include UVs and velocity attributes

Include UVs and velocity attributes when supported by your pipeline.
{% endstep %}

{% step %}

### Note source units and simulation frame rate

Note the source units and simulation frame rate.
{% endstep %}

{% step %}

### Test a small cache

Test a small cache first, then import the full simulation.
{% endstep %}
{% endstepper %}