Node Type: Shader
Node Description and Purpose
The Crater node is a displacement shader which creates and effect like a crater on the moon or a volcanic crater. A common way to create a Crater shader would be to make it part of the terrain. The easiest way to do this is to use the "Add Terrain" button in the Terrain project view. Click the button and choose the Crater shader from the Displacement Shader submenu.
- Center: Sets the position of the centre of the crater.
- Diameter: Sets the diameter of the crater.
- Depth: This sets the depth of the crater below the underlying terrain surface.
- Rim height: Sets the height of the rim above the underlying terrain surface.
- Rim skirt: This controls the width of the rim skirt. The skirt is the outside part of the rim, if you think of the edge around the top of the rim dividing the crater into inside and outside parts.
- Rim softness: This param controls the softness of the rim profile. At a setting of 0 the rim will come to a sharp peak. As the value increases the peaky top part smooths out more and more. The profile changes from a peak to being more like a hump. This movie shows the value going from 0 to 1:
- Rim tightness: This setting effects the steepness of the curve of the rim profile. Larger values give the rim a steeper and sharper appearance. This movie shows the effect of the value going from 0 to 10:
- Rim shader: TBC
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 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.