void CalculateTangentBinormal(TempVertexType vertex1, TempVertexType vertex2, TempVertexType vertex3, ref VectorType tangent, ref VectorType binormal)
{
var vector1 = new Vector3 {
X = vertex2.X - vertex1.X,
Y = vertex2.Y - vertex1.Y,
Z = vertex2.Z - vertex1.Z
};
var vector2 = new Vector3 {
X = vertex3.X - vertex1.X,
Y = vertex3.Y - vertex1.Y,
Z = vertex3.Z - vertex1.Z
};
var tuVector = new Vector2 {
X = vertex2.Tu - vertex1.Tu,
Y = vertex3.Tu - vertex1.Tu
};
var tvVector = new Vector2 {
X = vertex2.Tv - vertex1.Tv,
Y = vertex3.Tv - vertex1.Tv
};
var denominator = 1.0f / (tuVector.X * tvVector.Y - tuVector.Y * tvVector.X);
tangent.X = (tvVector.Y * vector1.X - tvVector.X * vector2.X) * denominator;
tangent.Y = (tvVector.Y * vector1.Y - tvVector.X * vector2.Y) * denominator;
tangent.Z = (tvVector.Y * vector1.Z - tvVector.X * vector2.Z) * denominator;
binormal.X = (tuVector.X * vector2.X - tuVector.Y * vector1.X) * denominator;
binormal.Y = (tuVector.X * vector2.Y - tuVector.Y * vector1.Y) * denominator;
binormal.Z = (tuVector.X * vector2.Z - tuVector.Y * vector1.Z) * denominator;
var tangentLength = new Vector3(tangent.X, tangent.Y, tangent.Z).Length();
tangent.X /= tangentLength;
tangent.Y /= tangentLength;
tangent.Z /= tangentLength;
var binormalLength = new Vector3(binormal.X, binormal.Y, binormal.Z).Length();
binormal.X /= binormalLength;
binormal.Y /= binormalLength;
binormal.Z /= binormalLength;
}
void CalculateModelVectors()
{
var faceCount = vertexCount / 3;
for (int i = 0, index = 0; i < faceCount; i++)
{
var tangent = new VectorType();
var binormal = new VectorType();
var normal = new VectorType();
var vertex1 = new TempVertexType {
X = model[index].X,
Y = model[index].Y,
Z = model[index].Z,
Tu = model[index].Tu,
Tv = model[index].Tv,
Nx = model[index].Nx,
Ny = model[index].Ny,
Nz = model[index].Nz
};
index++;
var vertex2 = new TempVertexType {
X = model[index].X,
Y = model[index].Y,
Z = model[index].Z,
Tu = model[index].Tu,
Tv = model[index].Tv,
Nx = model[index].Nx,
Ny = model[index].Ny,
Nz = model[index].Nz
};
index++;
var vertex3 = new TempVertexType {
X = model[index].X,
Y = model[index].Y,
Z = model[index].Z,
Tu = model[index].Tu,
Tv = model[index].Tv,
Nx = model[index].Nx,
Ny = model[index].Ny,
Nz = model[index].Nz
};
index++;
CalculateTangentBinormal(vertex1, vertex2, vertex3, ref tangent, ref binormal);
CalculateNormal(tangent, binormal, ref normal);
model[index - 1].Nx = normal.X;
model[index - 1].Ny = normal.Y;
model[index - 1].Nz = normal.Z;
model[index - 1].Tx = tangent.X;
model[index - 1].Ty = tangent.Y;
model[index - 1].Tz = tangent.Z;
model[index - 1].Bx = binormal.X;
model[index - 1].By = binormal.Y;
model[index - 1].Bz = binormal.Z;
model[index - 2].Nx = normal.X;
model[index - 2].Ny = normal.Y;
model[index - 2].Nz = normal.Z;
model[index - 2].Tx = tangent.X;
model[index - 2].Ty = tangent.Y;
model[index - 2].Tz = tangent.Z;
model[index - 2].Bx = binormal.X;
model[index - 2].By = binormal.Y;
model[index - 2].Bz = binormal.Z;
model[index - 3].Nx = normal.X;
model[index - 3].Ny = normal.Y;
model[index - 3].Nz = normal.Z;
model[index - 3].Tx = tangent.X;
model[index - 3].Ty = tangent.Y;
model[index - 3].Tz = tangent.Z;
model[index - 3].Bx = binormal.X;
model[index - 3].By = binormal.Y;
model[index - 3].Bz = binormal.Z;
}
}
