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Masks and blending

A mask is a heightfield interpreted as influence: 0 chooses A, 1 chooses B, and intermediate values transition between them.

Procedural masks​

Use Range for a soft elevation or analysis band, Threshold for a hard cutoff, Slope for steep ground, Flow Map for channels, Curvature for ridges and hollows, or Contours for repeating elevation lines. Blur softens a hard selection; Distance turns a hard boundary into an inward or outward falloff.

Painted masks​

Use Paint Mask when the location matters more than a mathematical rule. Paint over Height, Material, or Slope so strokes align with the evaluated feature beneath them.

Blend versus Combine​

  • Blend interpolates two heights under a mask. For materials, it selects or dithers between A and B.
  • Combine applies mathematical blend modes to heightfields and offers simpler A/B precedence for materials.

Example:

Grass material → Blend · A
Rock material  → Blend · B
Slope → Range → Blend · Mask
Blend · Out → Build Map · Material

If a mask looks reversed, insert Invert rather than rebuilding the upstream analysis.