A rectangle describing the UV region holding the texture passed to MeshGenerationContext.Allocate.
Internally, the texture passed to MeshGenerationContext.Allocate may either be used directly or is automatically integrated within a larger atlas. It is therefore required to use this property to scale and offset the UVs for the generated vertices in order to sample the correct texels. Correct use of MeshWriteData.uvRegion is simple: given an input UV in [0,1] range, multiply the UV by (uvRegion.width,uvRegion.height) then add uvRegion.xMin,uvRegion.yMin and store the result in Vertex.uv.