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Importing CAD models

We strongly recommend to use Pixyz Plugin in order to import your CAD model in Unity. You can contact Unity to purchase a license.

Pixyz Plugin 3.0

We support Pixyz plugin for Unity (v3.0.3+) starting from INTERACT 24.12. You can now install it directly from your Interact project by clicking INTERACT > Import > CAD model. It will install the recommended version for Interact. Otherwise, you can install it via the Unity Package Manager: com.unity.industry.toolkit.

Supported CAD files formats are :

  • Solidworks (.sldprt, .sldasm)
  • Catia V5, V6 (.CATPart, .CATProduct, .3dxml)
  • Siemens JT (.jt)
  • AutoCAD 3D (.dwg)
  • Autodesk Revit (.rvt)
  • Autodesk Navisworks (.nwc, .nwd)
  • Autodesk Inventor (.ipt, .iam)
  • Rhino3D (. 3dmbak)
  • SketchUp (.skp)
  • IGES (.igs)
  • STEP (.stp)
  • STL (.stl)
  • OBJ (.obj)
  • FBX (.fbx)

And much more ! See the full list of supported formats on Pixyz documentation.

Import your 3D CAD models into Unity 3D

To import your 3D CAD models into Unity3D:

  1. Click on INTERACT > Import > CAD model
  2. In the explorer, select your CAD file and click on Import Doing so will create a Scriptable Object that should be automatically selected. In the Inspector tab, you will see 3 tabs.

Model

In this tab, you will find some general settings for your CAD Import.

Rule Engine

In this tab, you will find the very important Rule Engine. When creating the 3D object from the CAD scriptable object, the given RuleSet will be executed. A RuleSet can contain several Rules, and each Rule contains one or more Actions. By default, a custom Interact RuleSet is used.

You can even go further by using Interact actions to apply physical behaviour to specific parts of the CAD model right after the import with the Rule Engine. Learn more on this powerful workflow on the dedicated page to Pixyz and INTERACT actions.

Load the generated 3D object in the scene

By default, the generated 3D object (a prefab) is not loaded in the scene. If the Load Prefab To Scene action is added to the RuleSet, it will be loaded once the RuleSet is done. Otherwise, you will have to manually add the prefab to your scene.

LODs

In this tab, you will find some optional settings for Level of detail generation. You can modify the global parameters and/or add new settings by clicking +

Model Import Settings

The settings used to import a 3D model will impact the performance of your simulation. There is no set of preferences that will work every time, as every use-case is different, with varying input data.

Import

  • Import Patch Boundaries: Import patch boundaries as lines. Only works if model is a CAD model (has BReps).
  • Import Lines: Import lines such as laser marking. Only works if model has lines.
  • Import Points: Import points, also called 'free vertices'. Points can be CAD position information or point cloud data for instance.
  • Import Metadata: Import metadata contained in the original model (if any), which is a piece of information that can be carried by any node of a CAD model’s hierarchy, that can carry information such as part numbers, ownership, physical properties, part type.
  • Import Variants: Import variants. A VariantsManager component will be added to the root GameObject if variants are found in the model.
  • Import PMI: Import PMI (Product and Manufacturing Information). A VariantsManager component will be added to the root GameObject if PMI are found in the model.
  • Import Animations: Import animations. Animator components will be added to the animated GameObjects if animations are found. To play the animation, open the Window > Animation window and select one of the animated GameObjects.
  • Import Nested Prefabs: Import CAD sub-assemblies (or Prototypes) as nested prefabs.

Transforms

Use the Transforms settings to adapt the imported model’s units/transformation to Unity3D units/coordinate system (meter as its default unit, left-handed coordinate system with Y as the Up axis).

  • Scale: Set the scale of the imported model.
  • Orientation: Pixyz can automatically orient your model according to its source coordinate system.
  • Left handed [If Orientation is Manual]: Use this setting to mirror a model from a right-handed coordinate system to a left-handed one.
  • Z-up [If Orientation is Manual]: Use this setting to rotate the model from Z-up to Y-up.

Geometry

  • Mesh Quality: Quality defines the density of the mesh that Pixyz creates. Depending if you import a CAD model (exact geometry) or a mesh model (tessellated geometry), Pixyz will either perform a Tessellation or a Decimation on the model (see documentation for more information and presets details: About 3D Models Types | About Decimation | About Tessellation).
  • Repair Instances: If true, Pixyz will attempt to detect similar GameObjects and recreate instances of their meshes. This can be used to repair instances or to simplify a model having similar parts that could be instantiated instead to reduce the number of unique meshes (reduces draw calls, GPU memory usage and file size).
  • Create CH. 0UVs: Create a new projected primary UV set (channel #0). Set the size of the projection box used to create UVs.
    • Caution: PiXYZ will override the existing UV set, do not use this setting if you wish to preserve the UVs embedded in the imported model (tessellated model).
  • Generate Lightmaps UVs: Create UVs for the lightmapper, so that light can be properly stored after being computed by Unity.

LOD - Level of Detail

When an object in the scene is a far away from the camera, the amount of details that can be seen on it is greatly reduced. However, the same number of triangles will be used to render the object, even though the detail will not be noticed. An optimization technique called Level Of Detail (LOD) rendering allows you to reduce the number of triangles rendered for an object as its distance from camera increases.

If you add one or more LOD in the LODs tab, a LOD Group component will be added to the root GameObject. This component allows to manage the distance from the camera at which each LOD is used.

LOD will reduce the load on the hardware and improve rendering performance.

Import & re-import

Once everything is correctly configured, you can press the Import button, visible at the bottom of the three tabs. This generates a prefab in the folder defined in Edit > Project Settings > Pixyz Plugin for Unity > Prefab Save Folder (by default, this folder is Assets/3DModels). Once generated, this prefab is automatically linked to the Scriptable Object:

The import button is now labeled "Re-Import". Re-importing the model will override the existing prefab, and will therefore update the already loaded instances of this prefab in the scene.

Remove Pixyz Plugin for Unity

You can remove Pixyz Plugin for Unity from your project. It will still work as long as you don't try to use the prefabs generated by Pixyz.