Comb
surface node
Adjust surface point normals by painting.
See also: Capture Layer Paint, Paint, Sculpt, UV Brush
The Comb brush is designed to allow you to intuitively adjust surface point normals in the viewer. The brush pushes point normals over as it moves across the surface.
Comb
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Click the
Comb tool on the Character tab. -
Set the Comb Lift, Radius, UV Radius, and Opacity on the operation controls toolbar.
-
Hold and drag your cursor over the vector attributes you want to comb.
You can comb other vector attributes by turning off the Override Normal checkbox and typing the name of the attribute you want to comb.
Parameters
Operation
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Comb Lift |
This controls how far the normals will be lifted off the surface. A value of 1 will cause them to move to an upright position, a value of 0 to lie flat in the dragged direction, and a value of -1 will cause them to move to a downright position. |
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Keep Normal Length |
If not set, the normals will be normalized when they are combed. If it is set, the length of the normals will be left unchanged by the comb operation. |
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Override Normal |
This allows you to specify an attribute other than N to comb. The attribute must be 3 floats in length. |
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Reset All Changes |
This button will restore the geometry to its original state. |
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Shape |
The basic shape of the brush: circle, square, or bitmap. |
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Bitmap |
What bitmap to use. The alpha channel becomes the brush. |
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Radius |
The radius of the brush when painting in the 3d viewport. |
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UV Radius |
The radius of the brush when painting in the 2d viewport. |
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Radius Pressure |
This controls how much effect the pressure of a stylus will have on the radius. A value of 1 means the radius will go from 0 to the amount in Radius. A value of 0 will mean the radius will always be constant, regardless of pressure. A value of 0.5 will mean the radius will be scaled between one half of Radius and Radius. |
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Depth |
If set, this limits how far the brush will paint along its axis. This can be used if connectivity is disabled to limit the effect of the brush. The first parameter is how deep below the surface the brush should penetrate. The second is how high above the surface it should stop. These values can be negative. |
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Brush Angle |
How far to rotate the brush. |
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Brush Squash |
Amount to squash the brush in the y direction before rotation. |
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Opacity |
The amount to affect the stencil mask. |
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Opacity Pressure |
This controls the how much effect the pressure of a stylus will have on the opacity. It obeys the same scaling as the Radius Pressure. |
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Brush Splatter |
A random noise in the brush’s opacity based upon the position on the brush. |
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Paper Grain |
A random noise on the object’s stencil mask based on the object position. |
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Soft Edge |
Percentage of the brush to be rolled off. |
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Kernel Function |
Which metaball kernel to use for the roll off. |
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Up Vector Type |
How the brush should be oriented on the surface:
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Up Vector |
The fixed up vector to orient brush to. |
Example files
CombGrass
$HFS/houdini/help/examples/nodes/sop/comb/CombGrass.cmd
This example shows how to use the Comb SOP to control the direction of point normals by interactively “painting” over the normals.
Two Comb SOPs are used to comb the normals on a grid in different directions. A Sequence Blend SOP blends between the two so that the normals look like they are swaying.
A simple line geometry is attached to those points.
The Comb SOP is a great way to animate things like hair and grass.
Usages in other examples
| Example name | Example for |
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