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Hi Amir,
Sorry about the delay in response.
The official Autodesk answer to this is no; CAT is not yet officially supported by FBX. We’re currently investigating this.
I can tell you (and anyone else reading this post) that we’ve identified 2 standout issues when using CAT with FBX, with the help of one of our users using 3ds Max, CAT and FBX, with the Unity game development tool. These issues are actually reproducible with 3ds Max and FBX, without the CAT plug-in installed, however since CAT relies on these functionalities, they do pose serious limitations with exporting CAT rigs to FBX. This is the conclusion that was recently sent to the client:
The 3ds Max FBX plug-in does not currently support the following:
1. PRS link inheritance properties
2. Non-orthogonal matrices
1. PRS link inheritance properties
Our plug-in is ignoring the Move/Rotate/Scale inheritance properties found in 3ds Max’ Hierarchy panel.
CAT uses these properties (replacing this rollout with its own) to perform squash and stretch. Again, FBX ignores these properties, whether in the CAT context or not. Once these scenes are exported, none of the inheritance properties are evaluated by the FBX exporter, and so the properties aren’t stored in the FBX file. Additionally, all imported scenes have these properties all set to active by default. So that’s FBX limitation number one in a nutshell. We will first look into supporting scale inheritance. As scale compensation (Maya’s equivalent) is already supported as a flag in our FBX SDK, this would be a modification to our 3ds Max FBX plug-in. The next step would be to support move and rotate inheritance as well, in the FBX SDK. We need to look into this.
2. Non-orthogonal matrices
I want to clarify that we are supporting standard non-uniform scaling with FBX technology. We are however not supporting non-uniform scaling along non-orthogonal matrices (where unique pivots are used for scaling). You can see this quickly by following these steps:
- Create a Cube primitive in the perspective viewport
- Rotate the cube along the Y-axis by 50 degrees, using the “View” Reference Coordinate System
- With “View” still as your reference coordinate system, scale the object in the X-axis by 50 percent
REVIEW: Your object is now skewed.
- FILE>EXPORT… to FBX
- FILE>IMPORT… using the Add to Scene option (to view the differences between the two objects)
RESULT: The skewing of the scale is gone in the imported object. Instead of being scaled according to a different pivot point (in this case, using the “View” coordinate system), it’s scaled according to the object’s local pivot. The object is still a squared cube. Unfortunately, our FBX warning doesn’t appear during the export, which would normally indicate that this type of transform is not supported (I’ve logged this as a defect). This is the warning you should get:
o The plug-in does not support the non-orthogonal TRS matrices. Such deformation or animation may not be converted correctly. Some information will be lost:
-Box01
To explain this further, I posted a message elsewhere on this forum explaining the error message:
To answer the initial question/post in this thread, you are receiving that error message because there is a non-uniform scaling of objects exported to FBX, using non-orthogonal matrices. In other words, a pivot has XYZ axes and when these axes are not perpendicular to each other (when non-local pivot scaling is performed, i.e. using the “View” Reference coordinate system for scaling in 3ds Max), skewing occurs with scaled objects. 3ds Max and Maya allow for this, but FBX currently does not support this data in the resulting exported file.
And so that’s limitation number two. It has also been logged as a suggestion for improved 3ds Max property support in FBX.
Let me know if you have further questions, Amir.
Trevor Adams
Autodesk FBX QA
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