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Using Splines to shape Stamp Brushes

Splines can be used to shape Errant Landscape Stamp Brushes. This feature provides you with more control over the brush shape, making it easier to create elements like rivers and mountain ranges.

Setup​

To set up a spline-shaped stamp brush:

  1. Go to the Stamp Brush Details panel.
  2. Change the Shape property to Spline.
  3. Select the appropriate spline component in the Spline Component property under Spline Params.

The spline component can be in any actor; it doesn't have to reside in the same actor as the stamp brush component.

tip

For easier manipulation, it's generally more convenient to place the spline component in the same actor as the stamp brush component. This allows you to move them together as a unit.

Spline Static Mesh Component​

One common application of splines in Errant Landscape Stamp Brushes is the creation of rivers. This often involves generating a water surface above the riverbed.

Errant Landscape includes dedicated components to create meshes from splines. These components use the same shaping logic as the stamp brush, ensuring consistent results.

tip

Although the Spline Static Mesh Component is part of Errant Landscape, you can use it with any spline-based project. It is shared as part of the plugin to maintain consistency between the brush and mesh shapes.

Moving Static Mesh​

By default, the Errant Landscape Spline Static Mesh Component automatically moves the mesh location to align with the spline. However, you may need to manually adjust the mesh position to better integrate it into your environment.

To disable the automatic positioning, toggle off the Auto Move to Spline Transform property.

tip

If you keep the Spline Static Mesh Component in the same actor as the spline, it will be easier to move them together without encountering transform mismatches.

Common Issues​

  1. Editor-Only Actors: Our brush actors are editor-only by default. If your static mesh resides inside such an actor, it won't be rendered in the game. Change this behavior by toggling the Is Editor Only Actor property in the actor settings.

  2. Collision Settings: Generated meshes include collision detection by default. To disable this feature, navigate to the Collision Presets property in the component settings and select NoCollision.

  3. Material Slot Visibility: If you find that the material slot is not visible or accessible, try selecting another component temporarily and then switch back to the original component. This usually refreshes the interface and makes the material slot visible.

  1. Errant Landscape Mode: We do not track spline changes outside the Errant Landscape Editor Mode. You need Errant Landscape mode active while making changes.

Blueprints​

The Blueprint helper function used to set up Stamp Brush spline references is editor-only, so the actor that uses it also needs to be editor-only.

If the river surface needs to exist in the game, do not place the Spline Static Mesh Component in that editor-only actor. Keep runtime components in a runtime actor.

info

When a Stamp Brush component is added directly to a Blueprint, editing an Actor instance created from that Blueprint can recreate the component, even when changing properties unrelated to the Stamp Brush. Recreating the component can temporarily disrupt its references to other objects, preventing the Stamp Brush from updating correctly. When used with a Spline Static Mesh Component this will cause automatic mesh updates to fail and requires manually using the Update Spline Mesh button in the component's Details panel. Repeated component recreation can also reduce editor performance.

Setting a Stamp Brush's spline reference with a Blueprint helper​

We provide a helper Blueprint function that can be used to set a Spline Reference in the Stamp Brush Component. This function can be used in Editor Only Actor construction scripts and Editor Utility Blueprints.

SplineBlueprintHelper

Stamp Brush and Spline in one editor-only Blueprint​

Create Stamp Brush Actor or add a Stamp Brush component to an editor-only Blueprint, then add a Spline component, set the brush's Shape to Spline, and assign the spline to the brush in the Construction Script using Set Spline Params On Stamp Brush Component.

Use this setup when you don't need a runtime Spline Static Mesh Component.

When the Stamp Brush and Spline are created by the same Blueprint component tree (SCS), the Stamp Brush can lose its spline reference after the Blueprint is edited. Reassign the spline to the Stamp Brush in the Construction Script, after the components have been recreated.

Stamp Brush in an editor-only Blueprint, Spline mesh in a runtime Blueprint​

Use this setup when you need a Spline Static Mesh Component, for example for a river surface that should render in the game.

Keep the Stamp Brush and editor-only setup logic in an editor-only actor. Place the Spline and Spline Static Mesh Component in a separate runtime actor. In Errant Landscape Editor Mode, both the Stamp Brush and Spline Static Mesh Component should track the Spline correctly.

The drawback is that you need to manage two actors.

Runtime generation​

Since Errant Landscape 1.7, you can use EL Runtime Stamp Brush Component and EL Runtime Spline Static Mesh Component to generate or modify a river from a spline during gameplay.

This allows the river to change in response to player interactions, but updating the landscape and mesh incurs a performance cost during gameplay. Use runtime generation when the river needs to change while the game is running; otherwise, use the editor workflow to bake changes into the landscape before the game starts.

tip

If you only need to create rivers in the editor, consider using Errant Paths. Errant Paths is currently the most convenient workflow for this use case, and we plan to continue improving it. Runtime generation is also planned for Errant Paths in the future.