Volume (.NET)

This example loads a .implicit file and calls ComputeVolume, which divides the body’s bounding box into a 100x100x100 grid of voxels, evaluates the body’s field (ImplicitBody.Value) at each voxel center, and estimates the volume as the count of inside voxels multiplied by the volume of a single voxel.

MainProgram.cs

using nTop.Core.Examples.Utils;
using nTop.Core.Wrapper;

namespace nTop.Core.Examples.Volume
{
    public partial class Volume
    {
        public static void Main()
        {
            // Get .implicit file path from user
            string path = CLI.LoadPrompt();

            // Create an ImplicitBody object
            var body = new ImplicitBody(path);

            // Compute the volume of the body
            int numVoxels = 100;
            var volume = ComputeVolume(body, numVoxels);

            // Cleanup
            body.Release();

            // For spherecube, true volume = 1458.149;
            // For sphere, true volume = 523.599;
            System.Console.WriteLine("Computed volume  = " + volume.ToString());
        }
    }
}

Volume.cs

using nTop.Core.Wrapper;

namespace nTop.Core.Examples.Volume
{
    public partial class Volume
    {
        /// <summary>Computes the (approximate) volume of an implicit body by using voxels</summary>
        /// <param name="body">The body whose volume we want</param>
        /// <param name="n">Number of voxels used will be n*n*n</param>
        /// <returns>The computed volume</returns>
        public static double ComputeVolume(ImplicitBody body, int n)
        {
            // Get the body's bounding box
            Box3d box = body.Box;

            double dx = (box.MaxX - box.MinX) / n;
            double dy = (box.MaxY - box.MinY) / n;
            double dz = (box.MaxZ - box.MinZ) / n;

            int count = 0;

            // Loop to count number of voxels inside the body
            for (int i = 0; i <= n; i++)
            {
                for (int j = 0; j <= n; j++)
                {
                    for (int k = 0; k <= n; k++)
                    {
                        double x = box.MinX + i * dx + 0.5 * dx;
                        double y = box.MinY + j * dy + 0.5 * dy;
                        double z = box.MinZ + k * dz + 0.5 * dz;
                        double fxyz = body.Value(x, y, z);
                        if (fxyz < 0) count++;  // voxel center is inside body, so add to count
                    }
                }
            }

            // Compute volume = number of inside voxels * voxel volume
            double volume = count * (dx * dy * dz);

            return volume;
        }
    }
}

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