Autodesk FBX Export

Format Description

"Autodesk FBX technology is one of the most widely used and supported platform-independent 3D data interchange solutions in the industry today. FBX plug-ins are included with Autodesk Maya and Autodesk 3ds Max software-providing high levels of interoperability between these packages - and with Autodesk MotionBuilder software, which supports FBX natively." -- Autodesk

CityEngine 2017.0 uses FBX 2017.0.1 (external link). CityEngine writes FBX files with the internal FBX file format 7.5.0.

Specific Export Options for FBX

The FBX exporter supports the following additional settings:

Option Description
Create Shape Groups If enabled, a transformation node is inserted for each shape (i.e. building). Meshes will not be merged by material across shapes.
File Type If set to binary, the file is stored in binary (native) format.
Embed Textures If enabled, textures are stored inside the binary FBX file.

CGA Mapping to FBX

As the FBX file format is quite verbose, we restrict ourselves to some selected examples for this manual. Please refer to the documentation provided by Autodesk (http://www.autodesk.com/products/fbx/overview).

Geometry and Transformation Data

CityEngine FBX Import Autodesk Maya
trigger
    --> primitiveCube() s(1,1,1) t(1,0,1)
        texture("uvtest.jpg")
        setupProjection(0,scope.xy,'.5,'.5)
        projectUV(0)
    
Exported scene via FBX in Autodesk Maya. Both "One Mesh Per .." options have been disabled to avoid merging any assets. In this case, each asset is parented to a transformation node. Else, the transformation is applied to the vertices.

Multi-Texturing and Layered Texture Nodes

CityEngine FBX Import Autodesk Maya
The CityEngine material model multiplies all six textures (if present) with the diffuse color. This example displays the layering/multiplicaton of "colormap" and "dirtmap". For FBX, CityEngine exports multiple textures as "layered texture nodes" whose blend modes are set to "multiply".

If at least one texture is set, Autodesk Maya loses the diffuse color settings upon FBX import, the ambient color is retained.

Working with per-texture transformations

CityEngine FBX Import Autodesk Maya
The CityEngine features material attributes to scale, translate and rotate textures independently of the actual texture coordinates stored inside the assets:
  • material.{...}.tu/tv = translate/offset texture
  • material.{...}.su/sv = scale/repeat texture
  • material.{...}.rw = rotate texture around face normal
Upon FBX import into maya, CityEngine's tu and tv attributes are mapped to the "Offset" parameter of maya's place2dTexture nodes, su/sv are mapped to the "RepeatUV" parameter and rw is mapped to the "Rotate Frame" parameter.

Further Reading

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