gistfile1.cs

        private void InitMarchingCubesAlgorithm()
        {
            // We need to calculate a list of the poly counts for each configuration of 'solid' and 'air' vertices.
            // There are eight vertices, each one representing a bit of a byte.

            // Look-up array for polygon count value that indicates how many (up to 5) polygons we need to create.
            var pc = new byte[256];
            // Look-up array for polygon edge connections, indicating which edges we need to connect together.
            var ec = new EdgeConnections[256];
            // Vertex neighbors. Each vertex of a cube has three neighbor vertices.
            int[,] n = { { 1, 3, 4 }, { 0, 2, 5 }, { 1, 3, 6 }, { 0, 2, 7 }, { 0, 5, 7 }, { 1, 4, 6 }, { 2, 5, 7 }, { 3, 4, 6 } };
            // Vertex edges. Each vertex has three outgoing edges.
            int[,] en = { { 0, 3, 8 }, { 0, 1, 9 }, { 1, 2, 10 }, { 2, 3, 11 }, { 4, 7, 8 }, { 4, 5, 9 }, { 5, 6, 10 }, { 6, 7, 11 } };

            var vs = new int[8];


            // Loop over all 254 possible variations of a cube's vertices.
            for (int i = 0; i < 255; ++i)
            {
                // this is our count for vertices that are solid.
                var v = 0;

                // Each vertex is either 'solid' or 'not solid', with eight vertices this means we
                // decompose a byte into bits in a loop.
                for (int j = 0; j < 8; v += vs[j++])
                    vs[j] = (i & (1 << j)) >> j;

                for (int nv = 0; nv < 8; ++nv)
                {
                    int nc = 1;

                    for (int k = 0; k < 3; ++k)
                        if (vs[n[nv, k]] > 0)
                            ++nc;

                    // We don't connect any edges where both vertices of the edge are solid.
                    if (nc == 4)
                        --v;
                }

                var c = new EdgeConnections();

                ec[i] = c;
                // assign our final polygon count for 'i' configuration.
                pc[i] = (byte)v;
            }
        }