/// <summary>
/// MarchCube performs the Marching Cubes algorithm on a single cube
/// </summary>
protected override void March(float x, float y, float z, float[] cube, IList <Vector3> vertList, IList <int> indexList, IList <Vector3> normalList)
{
int i, j, vert, idx;
int flagIndex = 0;
float offset = 0.0f;
float s = Surface;
//Find which vertices are inside of the surface and which are outside
for (i = 0; i < 8; i++)
{
if (cube[i] <= s)
{
flagIndex |= 1 << i;
}
}
//Find which edges are intersected by the surface
int edgeFlags = CubeEdgeFlags[flagIndex];
//If the cube is entirely inside or outside of the surface, then there will be no intersections
if (edgeFlags == 0)
{
return;
}
//Find the point of intersection of the surface with each edge
for (i = 0; i < 12; i++)
{
//if there is an intersection on this edge
if ((edgeFlags & (1 << i)) != 0)
{
int vert1 = EdgeConnection[i, 0];
int vert2 = EdgeConnection[i, 1];
offset = GetOffset(cube[vert1], cube[vert2]);
EdgeVertex[i].x = x + (VertexOffset[vert1, 0] + offset * EdgeDirection[i, 0]);
EdgeVertex[i].y = y + (VertexOffset[vert1, 1] + offset * EdgeDirection[i, 1]);
EdgeVertex[i].z = z + (VertexOffset[vert1, 2] + offset * EdgeDirection[i, 2]);
if (!Normals.ContainsKey(EdgeVertex[i]))
{
NormalVertex[i].x = Mathf.Lerp((cube[VertexSurround[0, vert1, 1]] - cube[VertexSurround[0, vert1, 0]]) / 2,
(cube[VertexSurround[0, vert2, 1]] - cube[VertexSurround[0, vert2, 0]]) / 2,
offset);
NormalVertex[i].y = Mathf.Lerp((cube[VertexSurround[1, vert1, 1]] - cube[VertexSurround[1, vert1, 0]]) / 2,
(cube[VertexSurround[1, vert2, 1]] - cube[VertexSurround[1, vert2, 0]]) / 2,
offset);
NormalVertex[i].z = Mathf.Lerp((cube[VertexSurround[2, vert1, 1]] - cube[VertexSurround[2, vert1, 0]]) / 2,
(cube[VertexSurround[2, vert2, 1]] - cube[VertexSurround[2, vert2, 0]]) / 2,
offset);
NormalVertex[i] = -NormalVertex[i].normalized;
Normals.Add(EdgeVertex[i], NormalVertex[i]);
}
else
{
NormalVertex[i] = Normals[EdgeVertex[i]];
}
}
}
//Save the triangles that were found. There can be up to five per cube
for (i = 0; i < 5; i++)
{
if (TriangleConnectionTable[flagIndex, 3 * i] < 0)
{
break;
}
idx = vertList.Count;
for (j = 0; j < 3; j++)
{
vert = TriangleConnectionTable[flagIndex, 3 * i + j];
indexList.Add(idx + WindingOrder[j]);
vertList.Add(EdgeVertex[vert]);
normalList.Add(NormalVertex[vert]);
}
}
}