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Masks Bar

The Masks Bar is where you create mask assets that are used on children of zones to control growth, for things such as world building.

Managing Mask Assets

Adding, removing, changing the name, reordering, and applying mask assets to the tree is done the same way for all of the assets. This process is described in Common Asset Settings.

Masks can also be assigned in the “Generation” group of every generator. Masks can be stacked on top of each other, allowing for both simple and complex rule sets governing the placement of nodes off of a generator's parent.

Common Settings

These settings at the top of the bar are common to all types of mask assets:


The action this mask causes.

InclusiveThis mask will determine where growth is allowed.
ExclusiveThis mask will determine where growth is not allowed.

Fuzziness relaxes the results of this mask when it is applied.


The type of mask can be set to Image, Terrain, or TexCoord. See further explanation below.

Image Masks

Image masks are grayscale images (or a single channel from a color image), often used to mask growth off zones. While the mask itself is applied to the children of the zone, the mask is mapped according to the texture coordinates of the parent zone.


The image file on disk used as the mask.


The channel source of the image mask. This can be set to grayscale, red, green, blue, or alpha.

Terrain Masks

Set a range for min/max elevation and slope. This type of mask could be used to push conifers up higher on a mountain or keep wide trees off steeper slopes.


The angle range allowing growth. A 0.0 slope is a completely flat area. A 1.0 slope is vertical.

Relative Elevation

The percentage range of the height of the parent zone where growth is allowed. 1.0 equals the top of the parent zone while 0.0 equals the bottom of the parent zone.

Absolute Elevation

An absolute elevation range in scene units.

Note: if your parent zone is not tall enough to fall in this range, no nodes will survive the mask.

TexCoord Masks

Generation can be limited to a subset of texture coordinates on the parent node. For instance, if your source object has texture coordinates greater than 1.0, you could allow growth only from areas of the mesh with texture coordinates in this range.

U and V

The minimum and maximum texture coordinate range of the parent zone allowing growth.