Blender Geometry Nodes Guide: Hair, Buildings, and UV Workflows

What you'll learn in this guide

Blender Geometry Nodes lets you build procedural geometry workflows with nodes. This guide covers three use cases: generating a denser hair system from a small number of guide curves, setting up a zone that processes geometry elements individually, and arranging UV islands. These methods can also inspire architectural visualization tasks such as deriving plants or structures from guide curves and preparing texture atlases.

For each operation, first identify the input geometry and the expected result; then configure the relevant node or zone for your purpose. The steps below are based on features described in the source documentation. Since the documentation does not provide menu paths for a specific interface version, none are given here.

Requirements

This guide requires Blender and Geometry Nodes functionality. The source documentation does not specify a particular Blender version or account requirements. Before getting started, check that the nodes in question are available in your version of Blender. The sources also do not provide information about pricing, hardware requirements, or the need to purchase a license.

For the hair example, you need geometry containing guide curves to use on a surface. For the UV example, you need UV islands to pack; for the individual-element workflow, you need geometry to work on and a domain to select. Identifying the right input geometry is a more useful starting point than changing settings at random.

1. Generate hair curves from guide curves

The Interpolate Hair Curves node creates new curves through interpolation from existing guide curves on a surface. The guides define the overall shape; the node adds curves between them to make the system denser. Make sure the input geometry contains the guide curves and surface you want to use. The result is a geometry output containing the generated curves.

Adjust the distribution and density to suit your needs:

1. Choose how root points are distributed across the surface. Random provides a random distribution. Poisson Disk creates a more even distribution by maintaining a minimum distance between roots.

2. Use Density to control the number of curves generated per unit of surface area. Higher values produce more curves. Adjust the density as needed when evaluating the result.

3. Consider the Density Mask input for localized control. Mask Texture uses the Surface UV Map input to select areas through a texture. According to the documentation, Density Mask is generally faster; using both methods together can help balance quality and performance.

4. Use Viewport Amount to reduce curve density for viewport performance. This value does not affect the final render density.

5. Check the Follow Surface Normal option to control how the curves attach to the surface. On surfaces with separate mesh islands, Part by Mesh Islands can prevent guides from blending across islands.

If the curves need to attach to the surface after deformation, also consider the Resting Surface option. The Blender documentation recommends enabling it when Interpolate Hair Curves is followed by Deform Curves on Surface. This can help the curves remain consistently positioned relative to the surface before deformation. Changing the Seed creates a different random distribution while keeping the other parameters unchanged.

2. Process geometry elements individually

For Each Geometry Element Zone lets you process the elements of input geometry individually. The documentation gives examples such as generating a different tree for each input curve or a unique building for each mesh face. The zone processes geometry element by element; in a suitable setup, each iteration can use the element geometry and index information.

Plan the workflow in this order:

1. Determine the element type to process. The Domain property selects which geometry domain's elements will be iterated over.

2. Use Selection to limit the subset being processed, if needed. This lets you work on selected elements instead of applying the operation to every input element.

3. Design the geometry to generate for each element. For example, the idea of a building per face requires a setup that creates geometry for each face.

4. Use the outputs as needed. The zone's main geometry outputs can create attributes on the main geometry; the generated geometry outputs combine the geometry created for the elements.

This approach is not always faster. The Blender documentation notes that processing many small geometry elements individually can be inefficient. The zone may also be unsuitable when working with a small amount of geometry: the flexibility of individual processing comes at the cost of Blender being able to optimize the operation less effectively. The Element output is not calculated if it is not used; leaving this unnecessary output unused can improve performance. Therefore, structure your iterations to avoid producing geometry split into unnecessarily small pieces.

3. Pack UV islands with Geometry Nodes

The Pack UV Islands node places UV islands within a defined UV region. It can scale and move the islands, optionally rotate them, and maintain a specified margin between them. Uses for this node include procedural UV generation, preparing texture atlases, and arranging UVs before baking.

First, define the UV input and the bounds of the packing region. Bottom Left and Top Right define the area in which the islands will be placed. Margin sets the distance between islands in UV space. The Rotate option allows islands to be rotated for more efficient packing. With Selection, you can choose the faces to include in packing: islands containing at least one selected face are affected; the UVs of islands made up only of unselected faces remain unchanged.

Choose a method based on the balance you need between precision and speed:

• Bounding Box uses the islands' axis-aligned bounding boxes. It is the fastest method, but may use UV space less efficiently.

• Convex Hull uses the islands' convex hulls. It offers a balance between speed and accuracy, but does not place islands inside gaps.

• Exact Shape takes the island's full shape into account, including concave regions and holes. It can provide tighter packing, but is the slowest option.

The node outputs UVs repositioned and scaled according to the settings. According to the Blender documentation, unlike the UV Editor operator, this node is non-destructive and can be controlled with procedural inputs.

Common pitfalls

Setting Density too high can make hair systems unnecessarily dense. Take the distribution method and mask into account as well; remember that lowering Viewport Amount for viewport inspection does not reduce the final render density. Increasing Interpolation Guides can create smoother transitions, but may slightly reduce performance. Distance to Guides limits how far a guide curve can influence the result.

Processing every small piece individually in an iteration zone can create an inefficient graph. Select only the elements you need and leave the Element output out of the workflow if it is not used. For UV packing, don't assume the most detailed method is always the best choice: Exact Shape provides tighter packing but is slower, while Bounding Box may be a faster option. If you want to pack only selected faces, check which islands are affected by the Selection setting.

Next steps

Try these three workflows with small, manageable inputs. For hair curves, adjust distribution, density, and the mask; for geometry iteration, change the domain selection and output structure; for UV packing, test the method, margin, and rotation settings in turn. Changing one setting at a time makes it easier to see which feature affects the result.

For architectural visualization teams, the example of generating a structure per face can help with thinking parametrically about repeated elements. However, how each element is generated depends on the node graph you build. Before moving on to production files, check performance and make sure the output meets the project's needs.

Sources and license

This guide is adapted into English from the Blender Manual documentation for “Interpolate Hair Curves,” “For Each Geometry Element Zone,” and “Pack UV Islands.” All three sources are licensed under CC BY-SA 4.0.