はじめに

Materials control the appearance of meshes, curves, volumes and other objects. They define the substance that the object is made of, its color and texture, and how light interacts with it.

Physically based materials can be created using the Principled BSDF, Principled Hair, and Principled Volume shaders. With these uber shaders, a wide variety of materials including plastic, glass, metal, cloth, skin, hair, smoke and fire can be created.

A flexible shading nodes system is used to set up textures and create entirely different types of materials like toon shading.

Setting up Materials

Materials can be created in either the Material properties, or in the Shader Editor. These provide a different view of the same shader nodes and material settings.

The default Shading workspace has a Shader Editor and a 3D Viewport that can be set to Material Preview or Rendered shading, to interactively preview how the material interacts with objects and lights in the scene.

Materials are data-blocks that can be assigned to one or more objects, and different materials can be assigned to different parts of meshes.

Image textures can be created from scratch in Texture Paint Mode, or by loading in existing images with the Image Texture node. A variety of procedural texture nodes is also available.

Components

Materials consist of three shaders, defining the appearance of the surface, the volume inside the object, and the displacement of the surface.

サーフェスシェーダー

The surface shader controls the textures and light interaction at the surface of the mesh.

ボリュームシェーダー

The volume shader defines the interior of the mesh. A material can have just a volume shader for cases like smoke and fire, or it can be combined with a surface shader for materials like cloudy glass.

Displacement

サーフェスの形状と内部のボリュームはディスプレイスメントシェーダーによって変化する場合が有ります。これを用いると、メッシュの表面をより詳細に表現するのにテクスチャを用いる事ができます。

設定によって、ディスプレイスメントは仮想的な物や、サーフェスの法線に対してのみディスプレイスメントの度合いを影響させるバンプマッピングと呼ばれる手法や、実際のディスプレイスメントと仮想のディスプレイスメントとを組み合わせる事ができます。

Physically Based Shading

The material system is built with physically-based rendering in mind, separating how a material looks and which rendering algorithm is used to render it. This makes it easier to achieve realistic results and balanced lighting, though there are a few things to keep in mind.

In order for materials to work well with global illumination, they should be energy conserving. That means they cannot reflect more light than comes in. This property is not strictly enforced, but if colors are in the range 0.0 to 1.0, and BSDFs are only mixed together with the Mix Shader node, this will automatically be true.

It is however, possible to break this, with color values higher than 1.0 or using the Add Shader node, but one must be careful when doing this to keep materials behaving predictably under various lighting conditions.