X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fcode.git;a=blobdiff_plain;f=src%2Fbezier.cpp;h=99611dc5d5ba99722e1e1fc05ea652abea703320;hp=f0e1f4d88721a693d25c94a2e2ce982534441fa4;hb=0361b11485ec41d2c2ddeb279abf846f777f5363;hpb=b3c2d3472c3b3d77eae0f66731a32b852dce11f0

diff --git a/src/bezier.cpp b/src/bezier.cpp
index f0e1f4d..99611dc 100644
--- a/src/bezier.cpp
+++ b/src/bezier.cpp
@@ -2,12 +2,103 @@
 
 #include <unordered_map>
 #include <cmath>
+#include <algorithm>
 
 using namespace std;
 
 namespace IPDF
 {
 
+vector<Real> SolveQuadratic(const Real & a, const Real & b, const Real & c, const Real & min, const Real & max)
+{
+	vector<Real> roots; roots.reserve(2);
+	if (a == 0 && b != 0)
+	{
+		roots.push_back(-c/b);
+		return roots;
+	}
+	Real disc(b*b - Real(4)*a*c);
+	if (disc < 0)
+	{
+		return roots;
+	}
+	else if (disc == 0)
+	{
+		Real x(-b/Real(2)*a);
+		if (x >= min && x <= max)
+			roots.push_back(x);
+		return roots;
+	}
+	
+	Real x0((-b - Sqrt(b*b - Real(4)*a*c))/(Real(2)*a));
+	Real x1((-b + Sqrt(b*b - Real(4)*a*c))/(Real(2)*a));
+	if (x0 > x1)
+	{
+		Real tmp(x0);
+		x0 = x1;
+		x1 = tmp;
+	}
+	if (x0 >= min && x0 <= max)
+		roots.push_back(x0);
+	if (x1 >= min && x1 <= max)
+		roots.push_back(x1);
+	return roots;
+}
+
+/**
+ * Finds the root (if it exists) in a monotonicly in(de)creasing segment of a Cubic
+ */
+
+static void CubicSolveSegment(vector<Real> & roots, const Real & a, const Real & b, const Real & c, const Real & d, Real & tl, Real & tu, const Real & delta)
+{
+	Real l = a*tl*tl*tl + b*tl*tl + c*tl + d;
+	Real u = a*tu*tu*tu + b*tu*tu + c*tu + d;
+	if ((l < 0 && u < 0) || (l > 0 && u > 0))
+		return;
+	
+	bool negative = (u < l); // lower point > 0, upper point < 0
+	while (tu - tl > delta)
+	{
+		Real t(tu+tl);
+		t /= 2;
+		Real m = a*t*t*t + b*t*t + c*t + d;
+		if (m > 0)
+		{
+			if (negative)
+				tl = t;
+			else
+				tu = t;
+		}
+		else if (negative)
+		{
+			tu = t;
+		}
+		else
+		{
+			tl = t;
+		}
+		//Debug("Delta is %f (%f - %f -> %f)", tu-tl, tu, tl, t);
+	}
+	roots.push_back(tl);
+}
+vector<Real> SolveCubic(const Real & a, const Real & b, const Real & c, const Real & d, const Real & min, const Real & max, const Real & delta)
+{
+	vector<Real> roots; roots.reserve(3);
+	Real tu(max);
+	Real tl(min);
+	vector<Real> turns(SolveQuadratic(a*3, b*2, c));
+	//Debug("%u turning points", turns.size());
+	for (unsigned i = 1; i < turns.size(); ++i)
+	{
+		tu = turns[i];
+		CubicSolveSegment(roots, a, b, c, d, tl, tu,delta);
+		tl = turns[i];
+	}
+	tu = max;
+	CubicSolveSegment(roots, a, b, c, d, tl, tu,delta);
+	return roots;
+}
+
 /**
  * Factorial
  * Use dynamic programming / recursion
@@ -45,4 +136,287 @@ 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
+ */
+
+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 = ((p1-p2)*3 + p3 - p0);
+	Real b = (p2 - p1*2 + p0)*2;
+	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 - a*c*4 < 0)
+	{
+		//Debug("No real roots");
+		return pair<Real, Real>(0,1);
+	}
+	vector<Real> tsols = SolveQuadratic(a, b, c);
+	if (tsols.size() == 1)
+		return pair<Real,Real>(tsols[0], tsols[0]);
+	else if (tsols.size() == 0)
+		return pair<Real, Real>(0,1);
+	
+	return pair<Real,Real>(tsols[0], tsols[1]);
+	
+}
+
+inline bool CompRealByPtr(const Real * a, const Real * b) 
+{
+	return (*a) < (*b);
+}
+
+/**
+ * Get top most *point* on Bezier curve
+ */
+pair<Real,Real> Bezier::GetTop() const
+{
+	pair<Real, Real> tsols = BezierTurningPoints(y0,y1,y2,y3);
+	Real tx0; Real ty0;
+	Real tx1; Real ty1;
+	Evaluate(tx0, ty0, tsols.first);
+	Evaluate(tx1, ty1, tsols.second);
+	vector<const Real*> v(4);
+	v[0] = &y0;
+	v[1] = &y3;
+	v[2] = &ty0;
+	v[3] = &ty1;
+	sort(v.begin(), v.end(), CompRealByPtr);
+	pair<Real,Real> result;
+	result.second = *v[0];
+	if (v[0] == &y0)
+	{
+		result.first = x0;
+	}
+	else if (v[0] == &y3)
+	{
+		result.first = x3;
+	}
+	else if (v[0] == &ty0)
+	{
+		result.first = tx0;
+	}
+	else if (v[0] == &ty1)
+	{
+		result.first = tx1;
+	}
+	return result;
+}
+
+/**
+ * Get bottom most *point* on Bezier curve
+ */
+pair<Real,Real> Bezier::GetBottom() const
+{
+	pair<Real, Real> tsols = BezierTurningPoints(y0,y1,y2,y3);
+	Real tx0; Real ty0;
+	Real tx1; Real ty1;
+	Evaluate(tx0, ty0, tsols.first);
+	Evaluate(tx1, ty1, tsols.second);
+	vector<const Real*> v(4);
+	v[0] = &y0;
+	v[1] = &y3;
+	v[2] = &ty0;
+	v[3] = &ty1;
+	sort(v.begin(), v.end(), CompRealByPtr);
+	pair<Real,Real> result;
+	result.second = *v[3];
+	if (v[3] == &y0)
+	{
+		result.first = x0;
+	}
+	else if (v[3] == &y3)
+	{
+		result.first = x3;
+	}
+	else if (v[3] == &ty0)
+	{
+		result.first = tx0;
+	}
+	else if (v[3] == &ty1)
+	{
+		result.first = tx1;
+	}
+	return result;
+}
+
+/**
+ * Get left most *point* on Bezier curve
+ */
+pair<Real,Real> Bezier::GetLeft() const
+{
+	pair<Real, Real> tsols = BezierTurningPoints(x0,x1,x2,x3);
+	Real tx0; Real ty0;
+	Real tx1; Real ty1;
+	Evaluate(tx0, ty0, tsols.first);
+	Evaluate(tx1, ty1, tsols.second);
+	vector<const Real*> v(4);
+	v[0] = &x0;
+	v[1] = &x3;
+	v[2] = &tx0;
+	v[3] = &tx1;
+	sort(v.begin(), v.end(), CompRealByPtr);
+	pair<Real,Real> result;
+	result.first = *v[0];
+	if (v[0] == &x0)
+	{
+		result.second = y0;
+	}
+	else if (v[0] == &x3)
+	{
+		result.second = y3;
+	}
+	else if (v[0] == &tx0)
+	{
+		result.second = ty0;
+	}
+	else if (v[0] == &tx1)
+	{
+		result.second = ty1;
+	}
+	return result;
+}
+
+
+/**
+ * Get left most *point* on Bezier curve
+ */
+pair<Real,Real> Bezier::GetRight() const
+{
+	pair<Real, Real> tsols = BezierTurningPoints(x0,x1,x2,x3);
+	Real tx0; Real ty0;
+	Real tx1; Real ty1;
+	Evaluate(tx0, ty0, tsols.first);
+	Evaluate(tx1, ty1, tsols.second);
+	vector<const Real*> v(4);
+	v[0] = &x0;
+	v[1] = &x3;
+	v[2] = &tx0;
+	v[3] = &tx1;
+	sort(v.begin(), v.end(), CompRealByPtr);
+	pair<Real,Real> result;
+	result.first = *v[3];
+	if (v[3] == &x0)
+	{
+		result.second = y0;
+	}
+	else if (v[3] == &x3)
+	{
+		result.second = y3;
+	}
+	else if (v[3] == &tx0)
+	{
+		result.second = ty0;
+	}
+	else if (v[3] == &tx1)
+	{
+		result.second = ty1;
+	}
+	return result;
+}
+
+vector<Real> Bezier::SolveXParam(const Real & x) const
+{
+	Real d(x0 - x);
+	Real c((x1 - x0)*Real(3));
+	Real b((x2 - x1)*Real(3) - c);
+	Real a(x3 -x0 - c - b);
+	vector<Real> results(SolveCubic(a, b, c, d));
+	for (unsigned i = 0; i < results.size(); ++i)
+	{
+		Vec2 p;
+		Evaluate(p.x, p.y, results[i]);
+	}
+	return results;
+}
+
+
+vector<Real> Bezier::SolveYParam(const Real & y) const
+{
+	Real d(y0 - y);
+	Real c((y1 - y0)*Real(3));
+	Real b((y2 - y1)*Real(3) - c);
+	Real a(y3 -y0 - c - b);
+	vector<Real> results(SolveCubic(a, b, c, d));
+	for (unsigned i = 0; i < results.size(); ++i)
+	{
+		Vec2 p;
+		Evaluate(p.x, p.y, results[i]);
+	}
+	return results;
+}
+
+vector<Vec2> Bezier::Evaluate(const vector<Real> & u) const
+{
+	vector<Vec2> result(u.size());
+	for (unsigned i = 0; i < u.size(); ++i)
+	{
+		Evaluate(result[i].x, result[i].y, u[i]);
+	}
+	return result;
 }
+
+/**
+ * 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