public static void Normalize(ref Vec3 v)
{
float len = v.X * v.X + v.Y * v.Y + v.Z * v.Z;
Debug.Assert(len >= 0.0f);
len = 1.0f / (float)Math.Sqrt(len);
v.X *= len;
v.Y *= len;
v.Z *= len;
}
public static int LongAxis(ref Vec3 v)
{
int i = 0;
if (Math.Abs(v.Y) > Math.Abs(v.X))
i = 1;
if (Math.Abs(v.Z) > Math.Abs(i == 0 ? v.X : v.Y))
i = 2;
return i;
}
public static void Dot(ref Vec3 u, ref Vec3 v, out float dot)
{
dot = u.X * v.X + u.Y * v.Y + u.Z * v.Z;
}
public static void Neg(ref Vec3 v)
{
v.X = -v.X;
v.Y = -v.Y;
v.Z = -v.Z;
}
public static void Sub(ref Vec3 lhs, ref Vec3 rhs, out Vec3 result)
{
result.X = lhs.X - rhs.X;
result.Y = lhs.Y - rhs.Y;
result.Z = lhs.Z - rhs.Z;
}
public Tess()
{
_normal = Vec3.Zero;
_bminX = _bminY = _bmaxX = _bmaxY = 0.0f;
_windingRule = WindingRule.EvenOdd;
_mesh = null;
_vertices = null;
_vertexCount = 0;
_elements = null;
_elementCount = 0;
}
private void ComputeNormal(ref Vec3 norm)
{
var v = _mesh._vHead._next;
var minVal = new float[3] { v._coords.X, v._coords.Y, v._coords.Z };
var minVert = new MeshUtils.Vertex[3] { v, v, v };
var maxVal = new float[3] { v._coords.X, v._coords.Y, v._coords.Z };
var maxVert = new MeshUtils.Vertex[3] { v, v, v };
for (; v != _mesh._vHead; v = v._next)
{
if (v._coords.X < minVal [0])
{
minVal [0] = v._coords.X;
minVert [0] = v;
}
if (v._coords.Y < minVal [1])
{
minVal [1] = v._coords.Y;
minVert [1] = v;
}
if (v._coords.Z < minVal [2])
{
minVal [2] = v._coords.Z;
minVert [2] = v;
}
if (v._coords.X > maxVal [0])
{
maxVal [0] = v._coords.X;
maxVert [0] = v;
}
if (v._coords.Y > maxVal [1])
{
maxVal [1] = v._coords.Y;
maxVert [1] = v;
}
if (v._coords.Z > maxVal [2])
{
maxVal [2] = v._coords.Z;
maxVert [2] = v;
}
}
// Find two vertices separated by at least 1/sqrt(3) of the maximum
// distance between any two vertices
int i = 0;
if (maxVal [1] - minVal [1] > maxVal [0] - minVal [0])
{
i = 1;
}
if (maxVal [2] - minVal [2] > maxVal [i] - minVal [i])
{
i = 2;
}
if (minVal [i] >= maxVal [i])
{
// All vertices are the same -- normal doesn't matter
norm = new Vec3 { X = 0.0f, Y = 0.0f, Z = 1.0f };
return;
}
// Look for a third vertex which forms the triangle with maximum area
// (Length of normal == twice the triangle area)
float maxLen2 = 0.0f, tLen2;
var v1 = minVert [i];
var v2 = maxVert [i];
Vec3 d1, d2, tNorm;
Vec3.Sub(ref v1._coords, ref v2._coords, out d1);
for (v = _mesh._vHead._next; v != _mesh._vHead; v = v._next)
{
Vec3.Sub(ref v._coords, ref v2._coords, out d2);
tNorm.X = d1.Y * d2.Z - d1.Z * d2.Y;
tNorm.Y = d1.Z * d2.X - d1.X * d2.Z;
tNorm.Z = d1.X * d2.Y - d1.Y * d2.X;
tLen2 = tNorm.X * tNorm.X + tNorm.Y * tNorm.Y + tNorm.Z * tNorm.Z;
if (tLen2 > maxLen2)
{
maxLen2 = tLen2;
norm = tNorm;
}
}
if (maxLen2 <= 0.0f)
{
// All points lie on a single line -- any decent normal will do
norm = Vec3.Zero;
i = Vec3.LongAxis(ref d1);
norm [i] = 1.0f;
}
}
