Wavefront OBJ
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OBJ is a widely used de facto standard in the 3D industry. The OBJ format is a popular plain text format, however, it has only basic geometry and material support.
Mesh: vertices, faces, edges, normals, UVs
Separation by groups/objects
Materials/textures
NURBS curves and surfaces
참고
There is no support for mesh Color Attributes, armatures, animation, lights, cameras, empty objects, parenting, or transformations.
참고
Blender now only supports complex node-based shading. OBJ having a fixed pipeline-like support of materials, this add-on uses the generic wrapper featured by Blender to convert between both.
경고
Importing very large OBJ-files (over a few 100mb), can use a lot of RAM.
사용법
Import geometry and curves to the OBJ format.
If there is a matching .MTL for the OBJ then its materials will be imported too.
특성
Import
Include
- Image Search
This enables a recursive file search if an image file can’t be found.
- Smooth Groups
Surround OBJ smooth groups by sharp edges. Note that these will only be displayed when the Edge Split modifier is enabled.
- Lines
Import OBJ lines and two-sided faces as mesh edges.
변형
- Clamp Size
OBJ-files often vary greatly in scale, this setting clamps the imported file to a fixed size.
- Forward / Up
Since many applications use a different axis for ‘Up’, these are axis conversion for these settings, Forward and Up axes – By mapping these to different axes you can convert rotations between applications default up and forward axes.
Blender uses Y Forward, Z Up (since the front view looks along the +Y direction). For example, it’s common for applications to use Y as the up axis, in that case -Z Forward, Y Up is needed.
Geometry
- Split/Keep Vertex Order
When importing an OBJ it’s useful to split up the objects into Blender objects, named according to the OBJ-file. However, this splitting loses the vertex order which is needed when using OBJ-files as morph targets.It also loses any vertices that are not connected to a face or edge so this must be disabled if you want to keep the vertex order and loose vertices.
- Split by Object & Split by Group
When importing an OBJ it’s useful to split up the objects into Blender objects, named according to the OBJ-file. However, this splitting loses the vertex order which is needed when using OBJ-files as morph targets. It also loses any vertices that are not connected to a face, so this must be disabled if you want to keep the vertex order.
As far as Blender is concerned OBJ Objects and Groups are no difference, since they are just two levels of separation, the OBJ groups are not equivalent to Blender groups, so both can optionally be used for splitting.
OBJ Export
Exporting OBJ-files is built into Blender without the need of an add-on. It’s documentation can be found here: OBJ Exporter </files/import_export/obj>.
Compatibility
Missing
Some of the following features are missing:
Advanced Material Settings – There are material options documented but very few files use them and there are few examples available.
Normals – Blender ignores normals from imported files, recalculating them based on the geometry.