X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fcode.git;a=blobdiff_plain;f=src%2Fbezier.cpp;h=da6533656847bf97eca50bba9212898a24754762;hp=f0e1f4d88721a693d25c94a2e2ce982534441fa4;hb=e35bf651e7ebfe4932e877780bb00397c41a7ec2;hpb=b3c2d3472c3b3d77eae0f66731a32b852dce11f0

diff --git a/src/bezier.cpp b/src/bezier.cpp
index f0e1f4d..da65336 100644
--- a/src/bezier.cpp
+++ b/src/bezier.cpp
@@ -2,6 +2,7 @@
 
 #include <unordered_map>
 #include <cmath>
+#include <algorithm>
 
 using namespace std;
 
@@ -45,4 +46,95 @@ Real Bernstein(int k, int n, const Real & u)
 	return Real(BinomialCoeff(n, k)) * Power(u, k) * Power(Real(1.0) - u, n-k);
 }
 
+
+/**
+ * Returns the parametric parameter at the turning point(s)
+ * In one coordinate direction
+ */
+
+static pair<Real, Real> BezierTurningPoints(const Real & p0, const Real & p1, const Real & p2, const Real & p3)
+{
+	// straight line
+	if (p1 == p2 && p2 == p3)
+	{
+		return pair<Real,Real>(0, 1);
+	}
+	Real a = (3*(p1-p2) + p3 - p0);
+	Real b = 2*(p2 - 2*p1 + p0);
+	Real c = (p1-p0);
+	if (a == 0)
+	{
+		if (b == 0)
+			return pair<Real, Real>(0,1);
+		Real t = -c/b;
+		if (t > 1) t = 1;
+		if (t < 0) t = 0;
+		return pair<Real, Real>(t, t);
+	}
+	Debug("a, b, c are %f, %f, %f", Float(a), Float(b), Float(c));
+	if (b*b - 4*a*c < 0)
+	{
+		Debug("No real roots");
+		return pair<Real, Real>(0,1);
+	}
+	pair<Real, Real> tsols = SolveQuadratic(a, b, c);
+	if (tsols.first > 1) tsols.first = 1;
+	if (tsols.first < 0) tsols.first = 0;
+	if (tsols.second > 1) tsols.second = 1;
+	if (tsols.second < 0) tsols.second = 0;
+	return tsols;
 }
+
+inline bool CompRealByPtr(const Real * a, const Real * b) 
+{
+	return (*a) < (*b);
+}
+
+/**
+ * Get Bounds Rectangle of Bezier
+ */
+Rect Bezier::SolveBounds() const
+{
+	Rect result;
+	pair<Real, Real> tsols = BezierTurningPoints(x0, x1, x2, x3);
+	
+	Real tp0; Real tp1; Real o;
+	Evaluate(tp0, o, tsols.first);
+	Evaluate(tp1, o, tsols.second);
+	
+	Debug("x: tp0 is %f tp1 is %f", Float(tp0), Float(tp1));
+	
+	vector<const Real*> v(4);
+	v[0] = &x0;
+	v[1] = &x3;
+	v[2] = &tp0;
+	v[3] = &tp1;
+	
+	// Not using a lambda to keep this compiling on cabellera
+	sort(v.begin(), v.end(), CompRealByPtr);
+
+	result.x = *(v[0]);
+	result.w = *(v[3]) - result.x;
+
+	// Do the same thing for y component (wow this is a mess)
+	tsols = BezierTurningPoints(y0, y1, y2, y3);
+	Evaluate(o, tp0, tsols.first);
+	Evaluate(o, tp1, tsols.second);
+	
+	
+	Debug("y: tp0 is %f tp1 is %f", Float(tp0), Float(tp1));
+	
+	v[0] = &y0;
+	v[1] = &y3;
+	v[2] = &tp0;
+	v[3] = &tp1;
+	sort(v.begin(), v.end(), CompRealByPtr);
+	
+	result.y = *(v[0]);
+	result.h = *(v[3]) - result.y;
+	
+	Debug("Solved Bezier %s bounds as %s", Str().c_str(), result.Str().c_str());
+	return result;
+}
+
+} // end namespace