Terrain paint utility editor helper functions.
| DrawBrushPreview | Draws a Terrain brush preview mesh from a heightmap PaintContext using the provided procedural material. |
| GetDefaultBrushPreviewMaterial | Returns the default brush preview material. This material supports procedural mesh generation for use with DrawBrushPreview. |
| ShowDefaultPreviewBrush | Helper function to display a default preview brush with no rotation or custom materials. |
| UpdateTerrainDataUndo | Updates the undo stack with a terrain operation. |