Materials¶
A PT MAT describes what a surface is made of. Give it to geometry with a PT GEO's Material parameter, or wire the geometry through it (see Several materials on one object). Geometry without a material renders white.
The basic surface¶
- Color is the surface colour.
- Roughness goes from a sharp, mirror-like reflection (0) to fully matte (1).
- Metallic turns the surface into a metal (1): it then reflects in its own colour, like gold or copper. Keep it at 0 for plastic, wood, paint, stone and skin.
- IOR sets how strongly the surface reflects at grazing angles. The default 1.5 suits most non-metals.
A few starting points:
| Material | Color | Metallic | Roughness | Other |
|---|---|---|---|---|
| Glossy plastic | any | 0 | 0.2 | |
| Matte paint | any | 0 | 0.8 | |
| Polished gold | 1, 0.77, 0.34 | 1 | 0.1 | |
| Brushed steel | 0.8, 0.8, 0.8 | 1 | 0.4 | |
| Car paint | any | 0 | 0.4 | Clear Coat 1 |
| Clear glass | 1, 1, 1 | 0 | 0 | Transparency 1, IOR 1.5 |
| Frosted glass | 1, 1, 1 | 0 | 0.3 | Transparency 1 |
Clear coat¶
Clear Coat adds a clear, glossy layer on top of the surface, like varnish or car paint: the surface below keeps its own roughness while the coat adds a sharp reflection. Tint colours the coat.
Glass and liquids¶
Set Transparency to 1 for glass, water or clear plastic. IOR then also sets how much light bends as it passes through: 1.33 for water, 1.5 for glass, 2.4 for diamond. Add Roughness for frosted glass.
- Absorption colours the material from the inside: thick parts get deeper in colour than thin edges, as in real coloured glass or liquids. The colour you set is the one that is absorbed, so absorbing red gives a cyan tint. Absorption Strength scales it.
- Dispersion splits light into its colours, as a prism or a diamond does. Small values are enough.
Light passes through several glass surfaces on its way through an object, so glass needs a few Bounces on the Pathtracer (see Troubleshooting).
Glowing surfaces¶
Emit makes a surface give off light in its Color. Emitting surfaces light the scene just like PT LIGHTs, so any geometry can be a light: a neon tube, a screen, a lava lamp.
- Render as Light Source off keeps the light but hides the glowing surface from the camera. It still shows in reflections.
- Normalize by Area (Attributes page) keeps the total light the same when you resize the object. Turn it off to make Emit the brightness of the surface itself.
See Lights and environment for more on lighting.
Textures¶
The Textures page takes TOPs. Each one is multiplied with its parameter: a Color texture with Color, a Roughness
texture with Roughness, and so on. The single-value textures (Metallic, Roughness, Emit, Transparency) use their
red channel. The geometry needs texture coordinates (Tex).
- Normal takes a tangent-space normal map, for detail such as scratches, grain or tiles without more geometry.
- Substance TOP takes a Substance TOP and uses its colour, metallic, roughness and normal maps at once.
- Emit and Transparency textures make only parts of a surface glow or become transparent, for patterns, cut-outs and leaves.
Values from attributes¶
Material values can also change across a surface, read from attributes of the geometry. On the Attributes page, set
a value to Point, Primitive or Vertex, and the Pathtracer reads an attribute of that name (Color,
Emit, Roughness and so on) from that kind of element. Where the geometry doesn't have the attribute, the
material's own value is used. Override if Attribute Exists replaces the geometry's values with the material's.
This is how to render point colours from a simulation, or make each copy of an object a different colour.
The Attributes page is shared
The Attributes page is the same for all PT MATs and PT LIGHTs in a project: changing it on one changes it on all of them, because the Pathtracer reads each attribute from one kind of element for the whole scene.