Fractal Warp Shader

Fractal Warp Shader

Overview

The Fractal warp shader distorts the 2D texture coordinates of the upstream shaders connected to its Main Input. In the example below you can see the effect of modifying the Scale value on the black shape which is approximately 100 kilometers long. Practical examples of this might be to transform a shape defined and displaced by a Simple shape shader into a snaking river that cuts across the terrain, or into a detailed hill or mountain.

Fractal warp of 2D texture coordinates by only adjusting Scale value.

Simple shape warped into river terrain.

Simple shape warped into hill.

Node Type: Transform/Warp Shader

Settings:

• Scale: Sets the size of the fractal pattern’s feature detail in meters and is similar to the Feature Scale parameter in a Power Fractal shader. Default value is 1000 metres and useful values depend on the size of the area to warp. Using too high a value relative to the size of the area you wish to affect, can result in unpredictable results as the fractal pattern can warp the areas to completely new positions and obliterate features. Values lower than the size of the area you want to warp can lead to more predictable results.

Effect of changing Scale values over 1000 metres.

Effect of changing Scale values over 1000 metres.

• Warp amount: Sets the amplitude of the warp effect. Default value is 1.0. A value of 0.0 results in no warping effect. Lower values result in less warping, while higher values result in greater warping up to the limits set by the Scale parameter.

Effect of changing Scale values over 1000 metres.

Effect of changing Scale values over 1000 metres.

• Variation:Visually adds random detail along the edge of the displaced areas. Negative values can break up an area into smaller and smaller fragments. A value of 0.0 should be avoided as it will cause all features to disappear. Increasing the value positively, reduces the amount of visual randomness, and the higher the value the more angular the effect becomes.

Effect of changing Variation values over 1000 metres.

Effect of changing Variation values over 1000 metres.

• Roughness: This value determines how quickly a change or deviation can occur over the Scale of the warp fractal pattern. Lower values result in fewer deviations, subdivisions and segmentations of an area and visually look more angular. Higher values allow for more deviations, subdivisions or segmentation of an area, and visually look smoother and more random. The default setting is 1, and recommended settings range from 0 to 2.0.

Effect of changing Roughness values over 1000 metres.

Effect of changing Roughness values over 1000 metres.

• Scale modulator: Accepts a shader as an input parameter to modify the Scale value. Where the scale modulator value evaluates to 0.0 no warp effect will occur, therefore this can act as a mask for the Scale parameter.

Checker pattern as Scale modulator over 1000 metres.	Checker pattern as Scale modulator over 1000 metres.
Power fractal as Scale modulator over 1000 metres.	Power fractal as Scale modulator over 1000 metres.

• Obey downstream smoothing filters: Allows the Fractal warp shader to take into consideration the “Smoothing scale” parameter of any Smoothing filter shaders located downstream from it in the node network. The “Smooth scale” value can force the Fractal warp shader not to generate features smaller than the “Smooth scale” value thereby smoothing its output.

Effect of enabling downstream Smoothing shaders over 1000 metres.

Effect of enabling downstream Smoothing shaders over 1000 metres.

• Mask by shader: When checked this shader is masked by the shader or function node assigned to this parameter.
• Fit mask to this: If this is checked the mask shader, specified with the Mask by shader parameter is given different texture coordinates in order to remap it into the texture space of this shader. Note that not all shaders use texture coordinates so this may have no effect.

• Invert mask: Check this to invert the values produced by the mask shader specified in the Mask by shader parameter.

Example Movies

Effect on displacement

Scale	Warp amount
Variation	Roughness

Effect on texture

Scale	Warp amount
Variation	Roughness

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.

A parameter is an individual setting in a node parameter view which controls some aspect of the node.

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.

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.