Shading / Textures

PBR (Physically Based Rendering) are best rendered with Cycles render engine. The material reacts to the environment and lighting in a physically realistic way.

HDRi textures can be used on the World shader to bring lighting to the scene. To turn it off in the display go to Render > Film and tick Transparent.

Texture Coordinates

For all the texture nodes use a Texture coordinate node (output Object) connected to a Mapping node (input Vector) in turn connected to the texture images (in/out Vectors) as illustrated below.

If you have Node Wrangler add-on activated, the keyboard shortcut CTRL + T will automatically generate these nodes.

Incidently, using Node Wrangler add-on you can select the Principled BSDF and use CTRL + SHIFT + T to open a bundle of maps and have them set-up as a Principled Texture.

Base Color

Keep the diffuse image in sRGB colorspace but if your mapping on an object use a Box projection instead of Flat.

Roughness

For roughness use Non-Color colorspace and Box projection as well.

Normal

For the normals use Non-Color colorspace and Box projection. Use a Normal map node to convert the output Color to the input Normal of the Principled BSDF

Displacement

The displacement avoids the Principled BSDF and goes directly into the Displacement input of the Material Output. This is because the displacement actually affects the geometry of the object whereas the Principled BSDF affects the way it looks.

Displacement must be activated in the Options under the Surface tab (choose : Displacement and Bump instead of Bump Only)

Displacement works best when there are many polygons on the object (use of a Subdivision Surface modifier is advised) and adds a good bit of detail. The drawback is it takes a lot more processing power and it's use is not advised for games.

Box Projection Method

Box projection has the advatage of being quick to setup, works with modifiers (e.g. bevel) and automatically updates if you modify the shape (e.g. extrude).

However, it does not work with a game engine, which require a proper UV Map (hence, we cannot choose the Object output of the Texture Coordinate Node).

UV Map Method

UV Map on the other hand requires to properly unwrap your object but once textured it can be exported easily to a game engine. The downside is you will see the seams, and there is no way to blend it so you should think carefully about where you place them, and keep your objects at a safe viewing distance. Another inconvenience is that you have to apply the modifiers for the seams to be set properly so it is slightly destructive.

Both these methods however keep the advantage of being able to easily change the PBR texture.

Texture painting

You can also load an image into a texture brush and paint directly on the object. In which case, choosing a random tiling and a large brush along with isolated-click painting instead of strokes can result in a good looking object. One drawback is the object has no roughness and the texture looks a bit flat.

In the case of texture painting, there is a way to add a bit of normals and bumpiness using the data from the image texture and a few color ramps as so :

Texture Atlas

A texture atlas is a custom image combining many different textures all in one image. It has the huge advantage of asking the CPU/GPU to load only one image and pick all the textures for different objects from parts of that image. The inconvenience is that each texture will have a lower pixel resolution (being part of a greater image)