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edge-segments.h
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edge-segments.h
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#pragma once
#include "Vector2.h"
#include "SignedDistance.h"
#include "EdgeColor.h"
namespace msdfgen {
// Parameters for iterative search of closest point on a cubic Bezier curve. Increase for higher precision.
#define MSDFGEN_CUBIC_SEARCH_STARTS 4
#define MSDFGEN_CUBIC_SEARCH_STEPS 4
/// An abstract edge segment.
class EdgeSegment {
public:
EdgeColor color;
EdgeSegment(EdgeColor edgeColor = WHITE) : color(edgeColor) { }
virtual ~EdgeSegment() { }
/// Creates a copy of the edge segment.
virtual EdgeSegment * clone() const = 0;
/// Returns the point on the edge specified by the parameter (between 0 and 1).
virtual Point2 point(double param) const = 0;
/// Returns the direction the edge has at the point specified by the parameter.
virtual Vector2 direction(double param) const = 0;
/// Returns the minimum signed distance between origin and the edge.
virtual SignedDistance signedDistance(Point2 origin, double ¶m) const = 0;
/// Converts a previously retrieved signed distance from origin to pseudo-distance.
virtual void distanceToPseudoDistance(SignedDistance &distance, Point2 origin, double param) const;
/// Adjusts the bounding box to fit the edge segment.
virtual void bounds(double &l, double &b, double &r, double &t) const = 0;
/// Moves the start point of the edge segment.
virtual void moveStartPoint(Point2 to) = 0;
/// Moves the end point of the edge segment.
virtual void moveEndPoint(Point2 to) = 0;
/// Splits the edge segments into thirds which together represent the original edge.
virtual void splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, EdgeSegment *&part3) const = 0;
virtual bool isDegenerate() const = 0;
class CrossingCallback {
public:
virtual ~CrossingCallback() {}
/// Callback for receiving intersection points. Winding is either:
/// +1 if the segment is increasing in the Y axis
/// -1 if the segment is decreasing in the Y axis
virtual void intersection(const Point2& p, int winding) = 0;
};
/// Calculate how many times the segment intersects the infinite ray that extends
/// to the right (+X) from the given point. Returns:
/// 0 for no intersection (or co-linear)
/// +1 for each intersection where Y is increasing
/// -1 for each intersection where Y is decreasing.
virtual int crossings(const Point2 &r, CrossingCallback *cb = NULL) const = 0;
};
/// A line segment.
class LinearSegment : public EdgeSegment {
public:
Point2 p[2];
LinearSegment(Point2 p0, Point2 p1, EdgeColor edgeColor = WHITE);
LinearSegment * clone() const;
Point2 point(double param) const;
Vector2 direction(double param) const;
SignedDistance signedDistance(Point2 origin, double ¶m) const;
void bounds(double &l, double &b, double &r, double &t) const;
void moveStartPoint(Point2 to);
void moveEndPoint(Point2 to);
void splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, EdgeSegment *&part3) const;
bool isDegenerate() const;
int crossings(const Point2 &r, CrossingCallback *cb = NULL) const;
};
/// A quadratic Bezier curve.
class QuadraticSegment : public EdgeSegment {
public:
Point2 p[3];
QuadraticSegment(Point2 p0, Point2 p1, Point2 p2, EdgeColor edgeColor = WHITE);
QuadraticSegment * clone() const;
Point2 point(double param) const;
Vector2 direction(double param) const;
SignedDistance signedDistance(Point2 origin, double ¶m) const;
void bounds(double &l, double &b, double &r, double &t) const;
void moveStartPoint(Point2 to);
void moveEndPoint(Point2 to);
void splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, EdgeSegment *&part3) const;
bool isDegenerate() const;
int crossings(const Point2 &r, CrossingCallback *cb = NULL) const;
};
/// A cubic Bezier curve.
class CubicSegment : public EdgeSegment {
public:
Point2 p[4];
CubicSegment(Point2 p0, Point2 p1, Point2 p2, Point2 p3, EdgeColor edgeColor = WHITE);
CubicSegment * clone() const;
Point2 point(double param) const;
Vector2 direction(double param) const;
SignedDistance signedDistance(Point2 origin, double ¶m) const;
void bounds(double &l, double &b, double &r, double &t) const;
void moveStartPoint(Point2 to);
void moveEndPoint(Point2 to);
void splitInThirds(EdgeSegment *&part1, EdgeSegment *&part2, EdgeSegment *&part3) const;
bool isDegenerate() const;
int crossings(const Point2 &r, CrossingCallback *cb = NULL) const;
};
}