Mesh Options
Export Tangents
Control whether vertex tangent data is written into the exported file.
Default: Off
Tangents define the local coordinate frame of a surface at each vertex. Renderers use this data to apply normal maps correctly. Most modern runtimes can calculate tangents on their own, so you normally do not need to include them in the file.
When to turn it ON
- Your target runtime requires authored tangent data and cannot generate its own (some custom engines or older platforms)
- Normal maps are shading incorrectly in the target viewer and you have ruled out other causes
- You have manually authored tangents that must be preserved exactly
When to leave it OFF
- Your runtime can generate tangents from normals and UVs — most modern viewers do this automatically
- You want to keep file sizes down — tangents add one
vec4(four floats) per vertex to every mesh primitive
What gets written
When enabled, a TANGENT attribute is added to each mesh primitive in the glTF file. Each tangent is a four-component vector where the fourth component (w) encodes the handedness of the tangent space (+1.0 or -1.0).
Tip
Viewers such as Babylon.js, three.js, and model-viewer all compute tangents automatically. Leave this off unless a specific runtime or pipeline step tells you it is needed.