/*
* split the curve at the midpoint, returning an array with the two parts
* Temporary storage is minimized by using part of the storage for the result
* to hold an intermediate value until it is no longer needed.
*/
void split(vector<Point> const &p, double t,
vector<Point> &left, vector<Point> &right) {
const unsigned sz = p.size();
//Geom::Point Vtemp[sz][sz];
vector<vector<Point> > Vtemp(sz);
for ( size_t i = 0; i < sz; ++i )
Vtemp[i].reserve(sz);
/* Copy control points */
std::copy(p.begin(), p.end(), Vtemp[0].begin());
/* Triangle computation */
for (unsigned i = 1; i < sz; i++) {
for (unsigned j = 0; j < sz - i; j++) {
Vtemp[i][j] = lerp(t, Vtemp[i-1][j], Vtemp[i-1][j+1]);
}
}
left.resize(sz);
right.resize(sz);
for (unsigned j = 0; j < sz; j++)
left[j] = Vtemp[j][0];
for (unsigned j = 0; j < sz; j++)
right[j] = Vtemp[sz-1-j][j];
}
/*
* Bezier :
* Evaluate a Bezier curve at a particular parameter value
* Fill in control points for resulting sub-curves.
*
*/
static Geom::Point
Bezier(Geom::Point const *V, /* Control pts */
unsigned degree, /* Degree of bezier curve */
double t, /* Parameter value */
Geom::Point *Left, /* RETURN left half ctl pts */
Geom::Point *Right) /* RETURN right half ctl pts */
{
//Geom::Point Vtemp[degree+1][degree+1];
std::vector<std::vector<Geom::Point> > Vtemp(degree+1);
for ( size_t i = 0; i < degree + 1; ++i )
Vtemp.reserve(degree+1);
/* Copy control points */
std::copy(V, V+degree+1, Vtemp[0].begin());
/* Triangle computation */
for (unsigned i = 1; i <= degree; i++) {
for (unsigned j = 0; j <= degree - i; j++) {
Vtemp[i][j] = lerp(t, Vtemp[i-1][j], Vtemp[i-1][j+1]);
}
}
for (unsigned j = 0; j <= degree; j++)
Left[j] = Vtemp[j][0];
for (unsigned j = 0; j <= degree; j++)
Right[j] = Vtemp[degree-j][j];
return (Vtemp[degree][0]);
}
QPointF evaluate(qreal t, BezierSegment *left, BezierSegment *right) const
{
int deg = degree();
if (! deg)
return QPointF();
QVector<QVector<QPointF> > Vtemp(deg + 1);
for (int i = 0; i <= deg; ++i)
Vtemp[i].resize(deg + 1);
/* Copy control points */
for (int j = 0; j <= deg; j++) {
Vtemp[0][j] = points[j];
}
/* Triangle computation */
for (int i = 1; i <= deg; i++) {
for (int j =0 ; j <= deg - i; j++) {
Vtemp[i][j].rx() = (1.0 - t) * Vtemp[i-1][j].x() + t * Vtemp[i-1][j+1].x();
Vtemp[i][j].ry() = (1.0 - t) * Vtemp[i-1][j].y() + t * Vtemp[i-1][j+1].y();
}
}
if (left) {
left->setDegree(deg);
for (int j = 0; j <= deg; j++) {
left->setPoint(j, Vtemp[j][0]);
}
}
if (right) {
right->setDegree(deg);
for (int j = 0; j <= deg; j++) {
right->setPoint(j, Vtemp[deg-j][j]);
}
}
return (Vtemp[deg][0]);
}
