Model batch rendering is currently limited to entities due to having two different ways of handling textures.
Materials & Surfaces.
Surfaces is doing it the correct way where you load a model and create a surface based on the mesh and add the correlated textures to that surface.
Materials will be created in a json file and you won't be able to have multi material models.

and currently the model batching is made on a per material basis and anything that runs with a surface will not be rendered even if they have a material in the background.

Directional shadow mapping is currently broken.
The orthographic projection matrix is there and seems to be setup correctly.
The light view matrix is missing however and this is most likely the cause of the issues with the shadows.

There are currently no support for multi-material models with the setup the engine currently supports for entities, forcing the content creator to put everything into a singular texture.
Which is highly inefficient and is quite bad.
Multi-material models needs to be addressed.

The Renderer class is currently very messy and hard to keep track of what's going on.
Proposing a RenderPass structure but the issue with that is the different context states.
RenderPass might not be a good fit?

The changes that I want to make can be related to model batch rendering.

High memory usage due to excessive use of new and excessively large GrowingArrays used everywhere. Prune these and see what actually has to be entities and world dwellers.
Only dynamic objects?

The terrain color goes whiter the further you go from ( 0, 0, 0 )
this is related to the PBR shader (deferred_ambient.ps, needs better naming)
The only lead I have right now is the specular calculations. Possibly the ambient calculations too.
Might want to split the PBR for objects and terrain to do different things.

Edit :
Issue is related to the fresnel calculation

Edit 2:
Issue is related to NdV