Displacement Shader

Displacement Shader

Node Description and Purpose:
The Displacement shader takes the values generated by the connected function nodes and turns them into displacement. You can connect any sort of function nodes to the input but the input value is converted to a scalar.

Node Type: Displacement Shader

Settings:

• Function: You connect the function node(s) which generate the displacement values to this input.
• Displacement direction: This popup list allows you to choose the direction that displacement is applied in. Any options in the popup list that have "(requires computed normal)" require that there be a Compute Terrain or Compute Normal connected somewhere above the node in the network to work properly. The popup has the following options:
  • Along vertical: Displacement will happen along the existing normals of the underlying object (i.e. the planet or a model) prior to any other displacement having been applied.
  • Along normal: Displacement will happen along the current surface normal.
  • Vertical only (requires computed normal): Displacement only happens along the normal of the underlying object (i.e. the planet or a model). The displacement is scaled by the difference between the object normal and the surface normal. Displacement is reduced as the angle between the normals approaches 90°.
  • Lateral only (requires computed normal): Displacement only occurs in the lateral plane, or in other words perpendicular to the normal of the underlying object.
  • Lateral normalized (requires computed normal): This is the same as Lateral only but the normal is normalised (scaled so it has a length of 1).
• Displacement multiplier: This multiplies the displacement values coming from the Function input. A value of 1 leaves the incoming values unchanged. A value of 2 would make the incoming values twice as large. A value of 0.5 would make them half as large. Negative values will invert the displacement.

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.

Literally, to change the position of something. In graphics terminology to displace a surface is to modify its geometric (3D) structure using reference data of some kind. For example, a grayscale image might be taken as input, with black areas indicating no displacement of the surface, and white indicating maximum displacement. In Terragen 2 displacement is used to create all terrain by taking heightfield or procedural data as input and using it to displace the normally flat sphere of the planet.

A scalar is a single number. 1, 200.45, -45, -0.2 are all examples of scalar values.

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.