// Up is along the positive Y axis (vUp in global coordinates)
// Forward is along the NEGATIVE Z axis (negative, remember! Its the opengl standard, its what the camera uses, and so it can be what objects use)
// Right is along the positive X axis.
void mlMatrixUtility::MatrixFromDirection(mlMatrix3x3 & result, const mlVector3D & vForward, const mlVector3D & vUp)
{
// This produces an identity matrix when vForward is along the Z axis, and vUp is along the Y axis.
// Alternative - an identity matrix when vForward is along the -ve Z axis, and vUp is along the Y axis.
// Compute our new look at vector, which will be
// the new negative Z axis of our transformed object.
result.K = vForward;
result.K.Normalise();
// Cross product of the new look at vector and the current
// up vector will produce a vector which is the new
// positive X axis of our transformed object.
result.I = mlVectorCross(result.K, vUp);
//result.I = mlVectorCross(vUp, result.K); // new
result.I.Normalise();
// Calculate the new up vector, which will be the
// positive Y axis of our transformed object. Note
// that it will lie in the same plane as the new
// look at vector and the old up vector.
result.J = mlVectorCross(result.I, result.K);
//result.J = mlVectorCross(result.K, result.I); // new
// Account for the fact that the geometry will be defined to
// point along the negative Z axis.
result.K *= -1.0f;
}
void mlMatrixUtility::MatrixFromVectorRotation(mlMatrix3x3 & result, const mlVector3D & normalisedVectorA, const mlVector3D & normalisedVectorB)
{
mlVector3D v = mlVectorCross(normalisedVectorA, normalisedVectorB);
mlFloat vSquared = v.MagnitudeSquared();
if (vSquared > mlFloatMin)
{
mlFloat e = normalisedVectorA * normalisedVectorB;
mlFloat h = (1.0f - e) / vSquared;
result.I.x = e + h * (v.x * v.x);
result.I.y = h * v.x * v.y + v.z;
result.I.z = h * v.x * v.z - v.y;
result.J.x = h * v.x * v.y - v.z;
result.J.y = e + h * (v.y * v.y);
result.J.z = h * v.y * v.z + v.x;
result.K.x = h * v.x * v.z + v.y;
result.K.y = h * v.y * v.z - v.x;
result.K.z = e + h * (v.z * v.z);
}
else
{
result.SetIdentity();
}
}
mlVector3D Face::getNormal()
{
mlVector3D p1 = v1->getPosition();
mlVector3D p2 = v2->getPosition();
mlVector3D p3 = v3->getPosition();
mlVector3D xy = p2 - p1;
mlVector3D xz = p3 - p1;
//xy.Normalise();
//xz.Normalise();
mlVector3D normal = mlVectorCross(xy, xz);
normal.Normalise();
return normal;
}
