Node Description and Purpose:
The Surface Layer is a very important node. It's the node you would most often use to create surface textures for the terrain. It's one of the more complex nodes in Terragen 2 and has a lot of settings. However these settings are grouped together for the particular aspect of the surface they effect and are quite straightforward.
If you used Terragen Classic you should find that many parts of the Surface Layer node are quite similar to Surface Layers, particularly the items in the Coverage and Breakup tab and the Altitude and Slope Constraints tabs. The other settings basically extend what the TG Classic Surface Layer could do.
Node Type: Surface Shader
- Apply colour: Check this checkbox to apply a basic surface colour to the whole surface layer. You can change the colour with the settings to the right or by using a colour function (see below).
Colour function: This setting lets you assign a function or shader to control the colour of the surface.
Enable test colour: If you check this checkbox the specified colour will be applied to the surface. The test colour lets you specify a particular colour to help show where a surface layer is being applied without having to change the basic colour. By default the test colour is magenta.
Coverage and breakup tab
- Coverage: This setting controls the coverage of the surface layer. It's a little like changing the transparency of the overall surface layer. A smaller value means the layer shows up less and the underlying surface layers show through more.
Fractal breakup: If this is checked the surface layer is broken up using the fractal assigned in the field to the right. This introduces more of a sense of randomness and texture to the surface. The amount of fractal breakup is specified in the controls immediately below. Larger numbers mean greater breakup.
Invert breakup: If this is checked the fractal breakup pattern is inverted, i.e. light parts become dark and vice versa.
Only breakup colour: If this is checked the fractal breakup only effects the colour of the surface layer and not the other characteristics of the surface layer.
Blend by shader: You can check this and specify a shader using the field to the left to have even greater control over where the surface shader appears. By default the surface layer will cover the whole planet. However you could, for example, use an Image Map Shader to control where the surface layer appears using an image. You could use a Painted Shader to paint where you want the surface layer to appear. You could use a Simple Shape Shader to limit the surface layer to a hexagonal area. There are lots of different things you can do.
Whiter parts of the shader show more of the surface layer. Shades of grey control the opacity or coverage of the layer. You can also control the RGB channels individually.
Invert breakup: If this is checked the blending shader is inverted, i.e. light parts become dark and vice versa.
Blend as coverage: If this is checked the blending shader is used to modify coverage rather than blending the surface shader as a whole. Blending as coverage allows for more sophisticated interaction with aspects of the shader such as fractal breakup.
Additional tabs for Surface Layer
A single object or device in the node network which generates or modifies data and may accept input data or create output data or both, depending on its function. Nodes usually have their own settings which control the data they create or how they modify data passing through them. Nodes are connected together in a network to perform work in a network-based user interface. In Terragen 2 nodes are connected together to describe a scene.
A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.