/// <summary>
/// Calculates the normals.
/// </summary>
/// <param name="vertices">vertex array of the shape</param>
/// <param name="shapeIndices">The shape mapping indices.</param>
/// <param name="shapeIndicesIndex">Index of the shape indices.</param>
public static void CalculateNormals(
VertexType[] vertices
, ILArray <int> shapeIndices
, Dictionary <int, List <int> > shapeIndicesIndex)
{
#if MEASURE_NORMAL_CALCULATION
DateTime start = DateTime.Now;
#endif
System.Diagnostics.Debug.Assert(vertices != null && vertices.Length > 0 && vertices[0].StoresNormals);
// first calculate the normal for all vertices
ILPoint3Df[] snormals = new ILPoint3Df[shapeIndices.Dimensions[1]];
for (int shapeCol = 0; shapeCol < snormals.Length; shapeCol++)
{
// crossproduct of vertex: (#1 - #0) x (#2 - #0)
int vi0 = shapeIndices.GetValue(0, shapeCol);
int vi1 = shapeIndices.GetValue(1, shapeCol);
int vi2 = shapeIndices.GetValue(2, shapeCol);
ILPoint3Df cross = ILPoint3Df.crossN(
vertices[vi1].Position - vertices[vi0].Position,
vertices[vi1].Position - vertices[vi2].Position);
snormals[shapeCol] = cross;
}
#if MEASURE_NORMAL_CALCULATION
TimeSpan crossDone = DateTime.Now - start;
DateTime startSorting = DateTime.Now;
System.Diagnostics.Debug.WriteLine("Normals Calculation: cross products in " + crossDone.TotalMilliseconds.ToString() + "ms");
#endif
// find all facettes using this vertex
for (int i = 0; i < vertices.Length; i++)
{
if (!shapeIndicesIndex.ContainsKey(i))
{
continue;
}
ILPoint3Df normal = new ILPoint3Df();
foreach (int shapeIdx in shapeIndicesIndex[i])
{
normal += snormals[shapeIdx];
}
// or should we let OpenGL normalize the normals...?
vertices[i].Normal = ILPoint3Df.normalize(normal);
//System.Diagnostics.Debug.Assert(
// Math.Abs(Math.Sqrt(
// vertices[0].Normal.X * vertices[0].Normal.X +
// vertices[0].Normal.Y * vertices[0].Normal.Y +
// vertices[0].Normal.Z * vertices[0].Normal.Z) - 1.0) < (double)MachineParameterFloat.eps);
}
#if MEASURE_NORMAL_CALCULATION
TimeSpan sortDone = DateTime.Now - startSorting;
System.Diagnostics.Debug.WriteLine("Normals Calculation: sorting done in " + sortDone.TotalMilliseconds.ToString() + "ms");
#endif
}
