public static void UpdateMaterials(Terrain terrain, int x, int y, int width, int height)
{
if (terrain == null)
{
throw new ArgumentNullException("terrain");
}
if (terrain.terrainData == null)
{
throw new ArgumentException("Invalid terrainData.");
}
float alphamapWidth = terrain.terrainData.alphamapWidth;
float alphamapHeight = terrain.terrainData.alphamapHeight;
UpdateMaterialsForTerrain(terrain, new Rect(((float) x) / alphamapWidth, ((float) y) / alphamapHeight, ((float) width) / alphamapWidth, ((float) height) / alphamapHeight));
}