#ifndef _BEZIER_H
#define _BEZIER_H
+#include <vector>
+#include <algorithm>
+
#include "real.h"
#include "rect.h"
namespace IPDF
// discriminant < 0 => 1 real root, 2 complex conjugate roots
////HACK: We know any roots we care about will be between 0 and 1, so...
+ Debug("Trying to solve %fx^3 + %fx^2 + %fx + %f", a,b,c,d);
Real maxi(100);
Real prevRes(d);
std::vector<Real> roots;
- for(int i = 0; i <= 100; ++i)
+ for(int i = -1; i <= 100; ++i)
{
Real x(i);
x /= maxi;
Real y = a*(x*x*x) + b*(x*x) + c*x + d;
- if (y == Real(0) || (y < Real(0) && prevRes > Real(0)) || (y > Real(0) && prevRes < Real(0)))
+ if ( ((y < Real(0)) && (prevRes > Real(0))) || ((y > Real(0)) && (prevRes < Real(0))))
{
+ Debug("Found root of %fx^3 + %fx^2 + %fx + %f at %f (%f)", a, b, c, d, x, y);
roots.push_back(x);
}
+ prevRes = y;
}
return roots;
{
// This function is very, very ugly, but with luck my derivation is correct (even if it isn't optimal, performance wise)
// (Very) rough working for the derivation is at: http://davidgow.net/stuff/cubic_bezier_reparam.pdf
+ Debug("Reparametrise: %f -> %f",t0,t1);
Bezier new_bezier;
Real tdiff = t1 - t0;
Real tdiff_squared = tdiff*tdiff;
new_bezier.y0 = Dy0 - Dy1 + Dy2 - Dy3 + new_bezier.y1 - new_bezier.y2 + new_bezier.y3;
+ Debug("(%f,%f),(%f,%f),(%f,%f),(%f,%f) -> (%f,%f),(%f,%f),(%f,%f),(%f,%f)", x0, y0, x1, y1, x2, y2, x3, y3, new_bezier.x0, new_bezier.y0, new_bezier.x1, new_bezier.y1, new_bezier.x2, new_bezier.y2, new_bezier.x3, new_bezier.y3);
return new_bezier;
}
+ std::vector<Bezier> ClipToRectangle(const Rect& r)
+ {
+ // Find points of intersection with the rectangle.
+ Debug("Clipping Bezier to Rect %s", r.Str().c_str());
+
+ // Convert bezier coefficients -> cubic coefficients
+ Real xa = x0-x1+x2-x3;
+ Real xb = x1 - Real(2)*x2 + Real(3)*x3;
+ Real xc = x2 - Real(3)*x3;
+ Real xd = x3 - r.x;
+
+ // Find its roots.
+ std::vector<Real> x_intersection = SolveCubic(xa, xb, xc, xd);
+
+ // And for the other side.
+ xd = x3 - r.x - r.w;
+
+ std::vector<Real> x_intersection_pt2 = SolveCubic(xa, xb, xc, xd);
+ x_intersection.insert(x_intersection.end(), x_intersection_pt2.begin(), x_intersection_pt2.end());
+
+ // Similarly for y-coordinates.
+ // Convert bezier coefficients -> cubic coefficients
+ Real ya = y0-y1+y2-y3;
+ Real yb = y1 - Real(2)*y2 + Real(3)*y3;
+ Real yc = y2 - Real(3)*y3;
+ Real yd = y3 - r.y;
+
+ // Find its roots.
+ std::vector<Real> y_intersection = SolveCubic(ya, yb, yc, yd);
+
+ // And for the other side.
+ yd = y3 - r.y - r.h;
+
+ std::vector<Real> y_intersection_pt2 = SolveCubic(ya, yb, yc, yd);
+ y_intersection.insert(y_intersection.end(), y_intersection_pt2.begin(), y_intersection_pt2.end());
+
+ // Merge and sort.
+ x_intersection.insert(x_intersection.end(), y_intersection.begin(), y_intersection.end());
+ std::sort(x_intersection.begin(), x_intersection.end());
+
+ Debug("Found %d intersections.\n", x_intersection.size());
+
+ std::vector<Bezier> all_beziers;
+ if (x_intersection.empty())
+ {
+ all_beziers.push_back(*this);
+ return all_beziers;
+ }
+ Real t0 = *(x_intersection.begin());
+ for (auto it = x_intersection.begin()+1; it != x_intersection.end(); ++it)
+ {
+ Real t1 = *it;
+ Debug(" -- t0: %f to t1: %f", t0, t1);
+ all_beziers.push_back(this->ReParametrise(t0, t1));
+ t0 = t1;
+ }
+ return all_beziers;
+ }
/** Evaluate the Bezier at parametric parameter u, puts resultant point in (x,y) **/
void Evaluate(Real & x, Real & y, const Real & u) const