Terrain Billboard Shader Incorrect

The diffuse lighting component of the TreeCreatorBarkRendertex.shader isn't limited to being above 0, which in the majority of cases causes black tree bark on tree creator trees (due to negative lighting).

Fix by modifying line 45 in TreeCreatorBarkRendertex.shader of the builtin shaders to:
o.params[j].r = max(0, nl ); // <- Changed!

See attached example with the corrected shader included.