private void AddCube(Vector3 center, ref List <Vector3> vertices, ref List <int> tris)
{
int index = 0;
//get the edge index position according to the function values
for (int i = 0; i < positions.Length; i++)
{
float value = Defines.Map(positions[i] * scale + center + transform.position);
index += value > 0.5 ? 1 << i : 0;
}
int[] edgesIndices = Defines.triTable[index];
for (int i = 0; i < edgesIndices.Length; i += 3)
{
if (edgesIndices[i] == -1)
{
break;
}
int c = vertices.Count;
//adapt each vertex to where the value actually crosses, not just in the middle of the edge
Vector3 p0 = GetVertexOnEdge(center, edgesIndices, i);
Vector3 p1 = GetVertexOnEdge(center, edgesIndices, i + 1);
Vector3 p2 = GetVertexOnEdge(center, edgesIndices, i + 2);
vertices.AddRange(new Vector3[] { p0, p1, p2 });
tris.AddRange(new int[] { c, c + 1, c + 2 });
}
}
private Vector3 GetVertexOnEdge(Vector3 center, int[] edgesIndices, int i)
{
//proportional offset: calculate where the value would exactly be the threshold, if we assume a linear growth
//this linear growth is - in most cases - wrong for SDF, but its much simpler to compute
Vector3 p0 = positions[(int)edges[edgesIndices[i]].x] * scale + center;
Vector3 p1 = positions[(int)edges[edgesIndices[i]].y] * scale + center;
float v0 = Defines.Map(p0 + transform.position);
float v1 = Defines.Map(p1 + transform.position);
float d = (0.5f - v0) / (v1 - v0);
Vector3 p = p0 + (p1 - p0) * d;
return(p);
}