//--------------------------------------------------------------------------------------------------
public static void SupportEdge(Transform tx, Vec3 e, Vec3 n, out Vec3 aresult, out Vec3 bresult)
{
n = Transform.MulT(tx.rotation, n);
Vec3 absN = Vec3.Abs(n);
Vec3 a = new Vec3(), b = new Vec3();
// x > y
if (absN.x > absN.y)
{
// x > y > z
if (absN.y > absN.z)
{
a.Set(e.x, e.y, e.z);
b.Set(e.x, e.y, -e.z);
}
// x > z > y || z > x > y
else
{
a.Set(e.x, e.y, e.z);
b.Set(e.x, -e.y, e.z);
}
}
// y > x
else
{
// y > x > z
if (absN.x > absN.z)
{
a.Set(e.x, e.y, e.z);
b.Set(e.x, e.y, -e.z);
}
// z > y > x || y > z > x
else
{
a.Set(e.x, e.y, e.z);
b.Set(-e.x, e.y, e.z);
}
}
double signx = Sign(n.x);
double signy = Sign(n.y);
double signz = Sign(n.z);
a.x *= signx;
a.y *= signy;
a.z *= signz;
b.x *= signx;
b.y *= signy;
b.z *= signz;
aresult = Transform.Mul(tx, a);
bresult = Transform.Mul(tx, b);
}
// http://box2d.org/2014/02/computing-a-basis/
public static void ComputeBasis(Vec3 a, ref Vec3 b, ref Vec3 c)
{
// Suppose vector a has all equal components and is a unit vector: a = (s, s, s)
// Then 3*s*s = 1, s = sqrt(1/3) = 0.57735027. This means that at least one component of a
// unit vector must be greater or equal to 0.57735027. Can use SIMD select operation.
if (Math.Abs(a.x) >= (0.57735027))
{
b.Set(a.y, -a.x, 0);
}
else
{
b.Set(0, a.z, -a.y);
}
b = Vec3.Normalize(b);
c = Vec3.Cross(a, b);
}
//--------------------------------------------------------------------------------------------------
public static void ComputeReferenceEdgesAndBasis(Vec3 eR, Transform rtx, Vec3 n, int axis, byte[] result, out Mat3 basis, out Vec3 e)
{
basis = new Mat3();
e = new Vec3();
n = Transform.MulT(rtx.rotation, n);
if (axis >= 3)
{
axis -= 3;
}
switch (axis)
{
case 0:
if (n.x > 0)
{
result[0] = 1;
result[1] = 8;
result[2] = 7;
result[3] = 9;
e.Set(eR.y, eR.z, eR.x);
basis.SetRows(rtx.rotation.ey, rtx.rotation.ez, rtx.rotation.ex);
}
else
{
result[0] = 11;
result[1] = 3;
result[2] = 10;
result[3] = 5;
e.Set(eR.z, eR.y, eR.x);
basis.SetRows(rtx.rotation.ez, rtx.rotation.ey, -rtx.rotation.ex);
}
break;
case 1:
if (n.y > 0)
{
result[0] = 0;
result[1] = 1;
result[2] = 2;
result[3] = 3;
e.Set(eR.z, eR.x, eR.y);
basis.SetRows(rtx.rotation.ez, rtx.rotation.ex, rtx.rotation.ey);
}
else
{
result[0] = 4;
result[1] = 5;
result[2] = 6;
result[3] = 7;
e.Set(eR.z, eR.x, eR.y);
basis.SetRows(rtx.rotation.ez, -rtx.rotation.ex, -rtx.rotation.ey);
}
break;
case 2:
if (n.z > 0)
{
result[0] = 11;
result[1] = 4;
result[2] = 8;
result[3] = 0;
e.Set(eR.y, eR.x, eR.z);
basis.SetRows(-rtx.rotation.ey, rtx.rotation.ex, rtx.rotation.ez);
}
else
{
result[0] = 6;
result[1] = 10;
result[2] = 2;
result[3] = 9;
e.Set(eR.y, eR.x, eR.z);
basis.SetRows(-rtx.rotation.ey, -rtx.rotation.ex, -rtx.rotation.ez);
}
break;
}
}
public void Set(double a, double b, double c, double d, double e, double f, double g, double h, double i)
{
ex.Set(a, b, c);
ey.Set(d, e, f);
ez.Set(g, h, i);
}
//--------------------------------------------------------------------------------------------------
// Vec3
//--------------------------------------------------------------------------------------------------
public static void Identity(ref Vec3 v)
{
v.Set(0, 0, 0);
}