Fixes crash if there are no normals generated and a normal map/tangent space is requested (it'll generate its own per-vertex normals).
Fixes crash if there are no normals generated and a normal map/tangent space is requested (it'll generate its own per-vertex normals).

GafferHQ/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer