I noticed something odd with lighting on a project I'm working on so re-created something simpler that shows the same thing.
With either distant or point lights in Karma, I find that object faces are receiving light when they shouldn't.
As a comparison, mantra renders as aspected and doesn't ‘bleed’ like Karma.
Wondering what's going on here and why the difference between Karma and Mantra.
…so, simply adding a normals to the geo helps Karma to render as expected.
I guess if no normals are present Mantra uses a normal perpendicular to the plane of the prim, pointing opposite for a reversed vertex order, while Karma takes the average direction of all vertices at each point, which gets averaged again accross the prim..something like that?
Mantra will by default add per-vertex normals if the mesh doesn't have any normal attributes (you can change it to point/shared normals by adding “Add Normals To Geometry” object property and and switching to “Point Normals”). Karma will add point normals (there's no equivalent property to switch the default).