Houdini 20.0 Nodes VOP nodes

Veins VOP node

Generates an anti-aliased vein pattern that can be used in any VEX context.

This operator generates an anti-aliased vein pattern that can be used in any VEX context.

The most important parameter is the Vein Projection type. The Linear projection generates stripe-like veins to which noise is added to resemble a marble-like pattern. The Cylindrical projection generates radial veins, also perturbed by noise, which yield a wood-like pattern if the Vein Direction (vdir) is given a predominantly Z bias, such as (0, 0, 1). The Spherical projection is useful for simulating agate-like patterns and other layered material cross-sections.

The Vein Direction (vdir) input, used with the Linear and Cylindrical projection types, determines the overall orientation of the veins. To better visualize the general vein orientation, you can temporarily reduce the Vein Frequency (vfreq) and the Noise Frequency (nfreq).

The Vein Frequency (vfreq) input controls the number of veins in the pattern by varying the “s” parametric value of the Ramps operator called internally. For wider or thinner veins, vary the Vein Attenuation (vatten) input. Vein Spacing (vspacing) works similarly to Vein Frequency in that it influences the number of veins in the pattern, except it works not with “s” but with the frequency of the ramps. In other words, vfreq is a domain multiplier, while vspacing determines the stripe frequency given a domain.

The Even Softness (evensoft) toggle determines whether the veins should attenuate softly on both sides of the vein backbone, or end sharply on one side. This feature may become useful in distinguishing between marbles, which have overall soft veins, and some types of wood, whose rings have a distinct one-sided sharpness.

Make sure at least the Position (pos) input is connected in order to notice any pattern. The easiest way to accomplish this is to pipe the global variable P into the pos input. Typically, however, you will use Rest Position or UV Space Change as inputs into pos. If you do need P, you will find it in the Global Variables operator.

To test the functionality of this operator, pipe its output into the Bias input of the Color Mix operator, then connect the resulting color into the Cf input of Output Variables.

See also

VOP nodes