| terrain | Reference terrain, defines terrain UV and object space. |
| brushCenterTerrainUV | Center point of the brush, in terrain UV space (0-1 across the terrain tile). |
| brushSize | Size of the brush, in terrain space. |
| brushRotationDegrees | Brush rotation in degrees (clockwise). |
BrushTransform Transform from terrain space to Brush UVs.
Creates a BrushTransform from the input parameters.