Totally break Quadtree Béziers.

[ipdf/code.git] / src / bezier.h

diff --git a/src/bezier.h b/src/bezier.h
index 8e7cedc..6dac0d5 100644 (file)
--- a/src/bezier.h
+++ b/src/bezier.h
@@ -183,6 +183,61 @@ namespace IPDF
                        return new_bezier;
                }
                
+               std::vector<Bezier> ClipToRectangle(const Rect& r)
+               {
+                       // Find points of intersection with the rectangle.
+
+                       // 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());
+
+                       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;
+                               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