public DAEVector3 Cross(DAEVector3 v)
{
return(new DAEVector3(
Y * v.Z - Z * v.Y,
Z * v.X - X * v.Z,
X * v.Y - Y * v.X));
}
public DAEVector4(DAEVector3 xyz, double w)
{
X = xyz.X;
Y = xyz.Y;
Z = xyz.Z;
W = w;
}
public static DAEMatrix4 Rotation(DAEVector3 axis, double angle)
{
if (angle == 0.0f)
{
return(DAEMatrix4.Identity);
}
axis = axis.Normalized;
double x, y, z, s, c, t;
x = axis.X;
y = axis.Y;
z = axis.Z;
s = (double)System.Math.Sin(angle);
c = (double)System.Math.Cos(angle);
t = 1 - c;
return(new DAEMatrix4(c + x * x * t, x * y * t - z * s, x * z * t + y * s, 0, y * x * t + z * s, c + y * y * t, y * z * t - x * s, 0, z * x * t - y * s, z * y * t + x * s, c + z * z * t, 0, 0, 0, 0, 1));
}
public DAEVector3 GetVector3(int index)
{
DAEVector3 result = new DAEVector3(0, 0, 0);
if (Stride > 0)
{
result.X = Values[index * Stride];
}
if (Stride > 1)
{
result.Y = Values[index * Stride + 1];
}
if (Stride > 2)
{
result.Z = Values[index * Stride + 2];
}
return(result);
}
internal static void GenerateMeshTangents(DAEVertexDescription[] vertices)
{
DAEVector3[] v = new DAEVector3[3];
DAEVector3[] n = new DAEVector3[3];
DAEVector3[] t = new DAEVector3[3];
for (int i = 0; i < vertices.Length; i += 3)
{
for (int j = 0; j < 3; j++)
{
v[j] = vertices[i + j].Vertex;
n[j] = vertices[i + j].Normal;
t[j] = vertices[i + j].TexCoord;
}
DAEVector3[] tangents = GenerateTriangleTangents(v, n, t);
for (int j = 0; j < 3; j++)
{
vertices[i + j].TexTangent = tangents[j];
vertices[i + j].TexBinormal = tangents[j].Cross(n[j]).Normalized;
}
}
}
/// <summary>
/// Generates tangents for a triangle. Source:
/// http://download.autodesk.com/us/maya/2009help/index.html?url=Appendix_A_Tangent_and_binormal_vectors.htm,topicNumber=d0e216694
/// </summary>
/// <param name="v">Vertices of the triangle</param>
/// <param name="n">Normals of the triangle</param>
/// <param name="t">Texture coords of the triangle</param>
/// <returns>the tangents</returns>
internal static DAEVector3[] GenerateTriangleTangents(DAEVector3[] v, DAEVector3[] n, DAEVector3[] t)
{
if (v.Length == 3 && n.Length == 3 && t.Length == 3)
{
DAEVector3[] finalTangentArray = new DAEVector3[3];
double[,] tangentArray = new double[3, 3];
double[] edge1 = new double[3];
double[] edge2 = new double[3];
DAEVector3 crossP;
// ==============================================
// x, s, t
// S & T vectors get used several times in this vector,
// but are only computed once.
// ==============================================
edge1[0] = v[1].X - v[0].X;
edge1[1] = t[1].X - t[0].X; // s-vector - don't need to compute
// this multiple times
edge1[2] = t[1].Y - t[0].Y; // t-vector
edge2[0] = v[2].X - v[0].X;
edge2[1] = t[2].X - t[0].X; // another s-vector
edge2[2] = t[2].Y - t[0].Y; // another t-vector
crossP = new DAEVector3(edge1).Cross(new DAEVector3(edge2)).Normalized;
bool degnerateUVTangentPlane = crossP.X == 0.0f;
if (degnerateUVTangentPlane)
{
crossP = new DAEVector3(1, crossP.Y, crossP.Z);
}
double tanX = -crossP.Y / crossP.X;
tangentArray[0, 0] = tanX;
tangentArray[1, 0] = tanX;
tangentArray[2, 0] = tanX;
// --------------------------------------------------------
// y, s, t
// --------------------------------------------------------
edge1[0] = v[1].Y - v[0].Y;
edge2[0] = v[2].Y - v[0].Y;
crossP = new DAEVector3(edge1).Cross(new DAEVector3(edge2)).Normalized;
degnerateUVTangentPlane = crossP.X == 0.0f;
if (degnerateUVTangentPlane)
{
crossP = new DAEVector3(1, crossP.Y, crossP.Z);
}
double tanY = -crossP.Y / crossP.X;
tangentArray[0, 1] = tanY;
tangentArray[1, 1] = tanY;
tangentArray[2, 1] = tanY;
// ------------------------------------------------------
// z, s, t
// ------------------------------------------------------
edge1[0] = v[1].Z - v[0].Z;
edge2[0] = v[2].Z - v[0].Z;
crossP = new DAEVector3(edge1).Cross(new DAEVector3(edge2)).Normalized;
degnerateUVTangentPlane = crossP.X == 0.0f;
if (degnerateUVTangentPlane)
{
crossP = new DAEVector3(1, crossP.Y, crossP.Z);
}
double tanZ = -crossP.Y / crossP.X;
tangentArray[0, 2] = tanZ;
tangentArray[1, 2] = tanZ;
tangentArray[2, 2] = tanZ;
// Orthnonormalize to normal
for (int i = 0; i < 3; i++)
{
DAEVector3 tangent = new DAEVector3(tangentArray[i, 0], tangentArray[i, 1], tangentArray[i, 2]);
finalTangentArray[i] = (tangent - (n[i] * (tangent.Dot(n[i])))).Normalized;
}
return(finalTangentArray);
}
return(null);
}
public static DAEMatrix4 Translation(DAEVector3 v)
{
return(Translation(v.X, v.Y, v.Z));
}
private double GetLuminance(DAEVector3 color)
{
return(color.X * 0.212671 + color.Y * 0.715160 + color.Z * 0.072169);
}
public double SmallAngle(DAEVector3 v)
{
double angle = Angle(v);
return((double)System.Math.Min(angle, System.Math.PI - angle));
}
public double Angle(DAEVector3 v)
{
return((double)System.Math.Acos(System.Math.Max(-1, System.Math.Min(1, this.Dot(v) / (this.Length * v.Length)))));
}
public double Dot(DAEVector3 v)
{
return(X * v.X + Y * v.Y + Z * v.Z);
}
