Brush Blending
Priority
When placing multiple brushes on top of each other, their priority decides in which order they get rendered and blended together. Brushes with higher priority are rendered later, thus blend on top of brushes with lower priority.
Brushes don't register to any single actor/list - there is no special asset that needs to be checked out when modifying them or changing their priority. As a result, multiple artists may work concurrently on different regions of a large landscape.
Brush's priority can be modified by changing its Brush Priority property (in the brush component) or by using the Priority Tool.
Priority Tool
Priority Tool shows the list of brushes ordered by their priority. Priority can be changed by drag & dropping a brush on the list or by typing brush priority directly.
Brush names are displayed using their visualization colors.
Priority is crucial when using the Replace Blend Method.
The Tools tab also contains utilities for priority conflict maintenance:
- Check for Priority Conflicts scans registered brushes and reports overlapping order-sensitive brushes that share the same priority.
- Fix Priority Conflicts on Selected Brushes increases priority on selected brushes until their order-sensitive conflicts are resolved, or until the maximum priority is reached.
Automatic Non-Conflicting Priority
Errant Landscape can automatically assign a non-conflicting priority when creating or duplicating brushes in Errant Landscape editor mode.
This is controlled by the Assign Non Conflicting Blend Priority editor user setting (bAssignNonConflictingBlendPriority) and is enabled by default.
When this option is enabled, a new or duplicated brush that uses an order-sensitive blend mode has its Brush Priority increased until it no longer conflicts with overlapping brushes that use matching order-sensitive blends.
If no conflict is found, the brush keeps its current priority.
This option helps avoid common conflicts while placing brushes, but it does not continuously rebalance existing levels. Use the priority conflict tools when you need to audit or fix brushes that already exist in the map.
Blend Modes
There are several ways to combine brushes. Depending on your needs, you may want to merge heightmaps, replace weightmaps, or use min/max operations on your biome masks.
Add and Subtract
This is the default mode, allowing brushes to blend through simple addition.
Only Add/Subtract
This mode is akin to the Add and Subtract mode but allows you to restrict the blending effect to either addition or subtraction.
Replace
This mode replaces everything below your brush with the brush itself. The contents underneath are determined by brush priority, as discussed in the priority section.
Min/Max
This mode retains only the highest or lowest values from both the brush and the combined landscape and brushes beneath it. It's particularly effective for blending brushes when you want to exclusively raise or lower the landscape.
Replace If Over/Under Threshold
This advanced blending mode allows you to replace the landscape below only if the value in your current brush exceeds or falls short of a specified threshold. It's useful for ensuring that the shape of your mask replaces the landscape precisely, as a square replacement would occur without a falloff.