View source for Twist and Shear Shader

[[File:TwistShear_00_GUI.png|none|470px|Twist and Shear Shader]]


== Overview ==
The shear effect displaces terrain horizontally, so that the vertical features of a heightfield or  procedural terrain can be made to lean in any direction, which is good for creating overhangs or large scale displacements across an entire terrain.  
[[File:TwistShear_07_OverhangCliffs.jpg|800 px | Twist and shear shader used to create overhanging terrain at top of mountains.]]


The effect can also be applied to clouds...

{|
|-
| [[File:TwistShear_05_LeanDirectionCloud.jpg|none|800 px | The shear effect can be applied to clouds as well as terrain.]]
|-
| [[File:TwistShear_06_LeanDirectionSmoke.jpg|none|800 px | The shear effect can be applied to clouds as well as terrain.]]
|}


...and even to water.

[[File:TwistShear_08_WaterShader.jpg|none|800 px | The shear effect can be applied to water shaders too.]]


''' Settings:'''

*'''Name:''' This setting allows you to apply a descriptive name to the node, which can be helpful when using multiple Twist and shear shader nodes in a project.


*'''Enable:''' When checked, the node is active and the settings below will affect the surface. When unchecked, the node is ignored.


*'''Lean factor:''' This setting is a multiplier that determines how much a terrain feature will lean.  When a terrain feature is 100% upright, a lean factor of 1 will result in the feature leaning at 45 degrees.  Values less than 1 result in the terrain features having less of a lean.  
<ul>
[[File:TwistShear_01_LeanFactor.jpg|none|800 px | Lean factor values ranging from -2.0 to 2.0]]
</ul>


*'''Lean direction:''' This setting controls whether the lean occurs in the positive or negative direction along each axis.  Positive values will cause the terrain to lean in the positive direction, and negative values the negative direction.  
<ul>
[[File:TwistShear_02_LeanDirection.jpg|none|800 px | Comparison of Lean factor values and Lean directions on the XYZ axis.]]
</ul>


*'''Base altitude:''' This is the altitude at which there is no displacement.  Above this altitude displacement is in the positive direction while below it the displacement is negative.  The amount of displacement varies with altitude based on the Lean factor.
<ul>
[[File:TwistShear_03_BaseAltitude.jpg|none|800 px | In this example the Base altitude value is increased in 10 metre increments on a terrain feature 50 metres tall. ]]
</ul>

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[[Category:Displacement Shader]]