Houdini 20.5 Nodes Geometry nodes

Cloud Shape Replicate geometry node

Generates primitive spheres used to model cumulus cloud-like shapes around existing primitive spheres.

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Since 20.0

Overview

This node is useful for cloud modeling to produce further spherical cloud mesh for cumulus cloud-like shapes for additional detail.

Parameters

General

Group

The subset of the input points or primitive to use for generating the cloud shapes.

Cloud Shapes

Scatter

Scatter on Surface

When this is on, it scatters points onto the surface of the incoming primitive spheres, otherwise the points are scattered inside the primitive sphere.

Point Separation

Sets the point density generated around the incoming primitive spheres. Smaller values will create denser point clouds, but will also reduce the size of the primitive spheres. Increase this value to create larger, more bulky shapes. Change the menu on the right side of this parameter from Set Uniform to Scale Attribute to control point separation by a float pscale point attribute.

Particle Scale

Uniformly scales the size of each generated primitive sphere.

Constraint To Source Point

When a point moves so far out from its source point that their representative spheres are not colliding, this will try to move back the point.

Jitter

Position Jitter

Randomizes the position of the scattered points around the source point in all directions.

Jitter Scale

Overall scale of the offset to move the points. Points are jittered by a value of -0.5 to 0.5 times this scale.

Seed

The random number seed used to generate the jitter values. Changing this will create a different set of jitter offsets.

Normal Jitter

Randomizes the position of the scattered points along the normal direction of each source point. When points are scattered, they are assigned a normal vector that is equal to the surface normal of the source sphere where the point is scattered. Calculated from the scattered point position minus the source sphere center.

Jitter Scale

Overall scale of normal jitter. Larger values could cause the scattered spheres to move further from their source.

Percent

Controls the number of points to apply the jitter to. The value of 10 means the jitter will affect 10% of all the scattered points.

Seed

The random number seed used to generate the jitter values. Changing this will create a different set of jitter offsets.

Scale by Noise

Scale by Noise

Randomizes the size of each generated primitive sphere using a spacial noise. This is useful to create size variation between spheres to make the generated cloud shape more interesting looking.

Scale Min

Sets the minimum amount of allowed scale by the spatial noise.

Scale Max

Sets the maximum amount of allowed scale by the spatial noise.

Element Size

Controls the base feature size of the generated noise. The value applies to each axis.

Offset

The offset into the noise field. Change the value of the Offset if the current size variation is undesirable.

Scale by Random

Do Random Scale

Randomizes the size of each generated primitive sphere using a random values. This is useful to create size variation between spheres to make the generated cloud shape more interesting looking.

Percent

Controls the number of points to apply the random scale to. The value of 15 means the scale will affect 15% of all the scattered points.

Scale

Controls the maximum allowed scale.

Seed

The random number seed used to generate the scale values. Changing this will create a different set of jitter offsets.

Directional Influence

Direction

When Pull Along Direction or Scale Along Direction is turned on, this controls the direction to be used. Change the menu on the right side of this parameter from Set Uniform to Use Attribute to control direction based on a direction point attribute. When the menu is set to Closest Intersection Points, intersections are detected between the input primitive spheres which control the direction. This can be used to elevate peaks even further.

Direction Attribute

The point attribute to use as the direction vector when Use Attribute is selected for the Direction parameter.

Align Along Direction

When turned on, the scattered spheres will be pulled to be aligned along the direction vector (given by Direction). This is useful to orient the newly scattered points along a given direction.

Pull Strength

Controls how much to pull the spheres to be aligned along the direction vector (given by Direction).

Directional Bias

Controls how much each scattered sphere needs to be aligned along the direction vector (given by Direction) based on the angle between the direction vector and the calculated normal. When this is set to 1, all scattered spheres will be closely aligned towards the direction vector. Lower this value to spread the spheres out more.

Note

When points are scattered, their normal vector is equal to the surface-normal of the source sphere where the points are scattered. Calculated from the scattered point position minus the source sphere center.

Scale Along Direction

When turned on, randomizes the size of each generated primitive sphere based on the direction vector (given by Direction).

Scale Min

Sets the minimum amount of an allowed scale for spheres with normals that facing in the opposite direction of the direction vector (given by Direction).

Scale Max

Sets the maximum amount of an allowed scale for spheres with normals that facing in the same direction as the direction vector (given by Direction).

Directional Bias

Controls how much to scale the size of each scattered sphere based on the angle between the direction vector (given by Direction) and the calculated normal vector. When this is set to 1, only spheres with a normal vector pointing in the same direction as the direction vector will be scaled by Scale Max. Lower this value to make more and more spheres affected by the maximum scale.

Note

When points are scattered, their normal vector is equal to the surface-normal of the source sphere where the points are scattered. Calculated from the scattered point position minus the source sphere center.

Output

Ouptut

Up Vector Bias

When turned on, the spheres will be aligned based on their normal direction and the up vector. Use this to help flatten the bottom of the cloud shape.

Note

When points are scattered, they are assigned a normal vector that is equal to the surface-normal of the source sphere where the points are scattered. Calculated from the scattered point position minus the source sphere center.

Up Vector

User specified up vector for alignment.

Update Normals

When turned on, the normals are updated from the scattered point position minus the source sphere center.

Keep Input Geometry

When turned on, the source input points are kept.

See also

Geometry nodes