CommonLib.cs

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using System;

namespace TextureTools.TexLibraries
{
    /// <summary>
    /// Class CommonLib
    /// </summary>
    public class CommonLib
    {
        /// <summary>
        /// Calculates the mip level from a specified size.
        /// </summary>
        /// <param name="size">The size.</param>
        /// <param name="minimumSizeLastMip">The minimum size of the last mip.</param>
        /// <returns>The mip level.</returns>
        /// <exception cref="System.ArgumentOutOfRangeException">Value must be > 0;size</exception>
        public static int CalculateMipCountFromSize(int size, int minimumSizeLastMip = 4)
        {
            if (size <= 0)
            {
                throw new ArgumentOutOfRangeException("Value must be > 0", "size");
            }

            if (minimumSizeLastMip <= 0)
            {
                throw new ArgumentOutOfRangeException("Value must be > 0", "minimumSizeLastMip");
            }

            int level = 1;
            while ((size/2) >= minimumSizeLastMip)
            {
                size = Math.Max(1, size / 2);
                level++;
            }
            return level;
        }

        /// <summary>
        /// Calculates the mip level from a specified width,height,depth.
        /// </summary>
        /// <param name="width">The width.</param>
        /// <param name="height">The height.</param>
        /// <param name="depth">The depth.</param>
        /// <param name="minimumSizeLastMip">The minimum size of the last mip.</param>
        /// <returns>The mip level.</returns>
        /// <exception cref="System.ArgumentOutOfRangeException">Value must be &gt; 0;size</exception>
        public static int CalculateMipCount(int width, int height, int minimumSizeLastMip = 4)
        {
            return Math.Min(CalculateMipCountFromSize(width, minimumSizeLastMip), CalculateMipCountFromSize(height, minimumSizeLastMip));
        }
    }
}