msdfgen/core/contour-combiners.cpp

#include "contour-combiners.h"

#include <cfloat>
#include "arithmetics.hpp"

namespace msdfgen {

static void initDistance(real &distance) {
    distance = -FLT_MAX;
}

static void initDistance(MultiDistance &distance) {
    distance.r = -FLT_MAX;
    distance.g = -FLT_MAX;
    distance.b = -FLT_MAX;
}

static real resolveDistance(real distance) {
    return distance;
}

static real resolveDistance(const MultiDistance &distance) {
    return median(distance.r, distance.g, distance.b);
}

template <class EdgeSelector>
SimpleContourCombiner<EdgeSelector>::SimpleContourCombiner(const Shape &shape) { }

template <class EdgeSelector>
void SimpleContourCombiner<EdgeSelector>::reset(const Point2 &p) {
    shapeEdgeSelector.reset(p);
}

template <class EdgeSelector>
EdgeSelector &SimpleContourCombiner<EdgeSelector>::edgeSelector(int) {
    return shapeEdgeSelector;
}

template <class EdgeSelector>
typename SimpleContourCombiner<EdgeSelector>::DistanceType SimpleContourCombiner<EdgeSelector>::distance() const {
    return shapeEdgeSelector.distance();
}

template class SimpleContourCombiner<TrueDistanceSelector>;
template class SimpleContourCombiner<PseudoDistanceSelector>;
template class SimpleContourCombiner<MultiDistanceSelector>;
template class SimpleContourCombiner<MultiAndTrueDistanceSelector>;

template <class EdgeSelector>
OverlappingContourCombiner<EdgeSelector>::OverlappingContourCombiner(const Shape &shape) {
    windings.reserve(shape.contours.size());
    for (std::vector<Contour>::const_iterator contour = shape.contours.begin(); contour != shape.contours.end(); ++contour)
        windings.push_back(contour->winding());
    edgeSelectors.resize(shape.contours.size());
}

template <class EdgeSelector>
void OverlappingContourCombiner<EdgeSelector>::reset(const Point2 &p) {
    this->p = p;
    for (typename std::vector<EdgeSelector>::iterator contourEdgeSelector = edgeSelectors.begin(); contourEdgeSelector != edgeSelectors.end(); ++contourEdgeSelector)
        contourEdgeSelector->reset(p);
}

template <class EdgeSelector>
EdgeSelector &OverlappingContourCombiner<EdgeSelector>::edgeSelector(int i) {
    return edgeSelectors[i];
}

template <class EdgeSelector>
typename OverlappingContourCombiner<EdgeSelector>::DistanceType OverlappingContourCombiner<EdgeSelector>::distance() const {
    int contourCount = (int) edgeSelectors.size();
    EdgeSelector shapeEdgeSelector;
    EdgeSelector innerEdgeSelector;
    EdgeSelector outerEdgeSelector;
    shapeEdgeSelector.reset(p);
    innerEdgeSelector.reset(p);
    outerEdgeSelector.reset(p);
    for (int i = 0; i < contourCount; ++i) {
        DistanceType edgeDistance = edgeSelectors[i].distance();
        shapeEdgeSelector.merge(edgeSelectors[i]);
        if (windings[i] > 0 && resolveDistance(edgeDistance) >= real(0))
            innerEdgeSelector.merge(edgeSelectors[i]);
        if (windings[i] < 0 && resolveDistance(edgeDistance) <= real(0))
            outerEdgeSelector.merge(edgeSelectors[i]);
    }

    DistanceType shapeDistance = shapeEdgeSelector.distance();
    DistanceType innerDistance = innerEdgeSelector.distance();
    DistanceType outerDistance = outerEdgeSelector.distance();
    real innerScalarDistance = resolveDistance(innerDistance);
    real outerScalarDistance = resolveDistance(outerDistance);
    DistanceType distance;
    initDistance(distance);

    int winding = 0;
    if (innerScalarDistance >= real(0) && fabs(innerScalarDistance) <= fabs(outerScalarDistance)) {
        distance = innerDistance;
        winding = 1;
        for (int i = 0; i < contourCount; ++i)
            if (windings[i] > 0) {
                DistanceType contourDistance = edgeSelectors[i].distance();
                if (fabs(resolveDistance(contourDistance)) < fabs(outerScalarDistance) && resolveDistance(contourDistance) > resolveDistance(distance))
                    distance = contourDistance;
            }
    } else if (outerScalarDistance <= real(0) && fabs(outerScalarDistance) < fabs(innerScalarDistance)) {
        distance = outerDistance;
        winding = -1;
        for (int i = 0; i < contourCount; ++i)
            if (windings[i] < 0) {
                DistanceType contourDistance = edgeSelectors[i].distance();
                if (fabs(resolveDistance(contourDistance)) < fabs(innerScalarDistance) && resolveDistance(contourDistance) < resolveDistance(distance))
                    distance = contourDistance;
            }
    } else
        return shapeDistance;

    for (int i = 0; i < contourCount; ++i)
        if (windings[i] != winding) {
            DistanceType contourDistance = edgeSelectors[i].distance();
            if (resolveDistance(contourDistance)*resolveDistance(distance) >= real(0) && fabs(resolveDistance(contourDistance)) < fabs(resolveDistance(distance)))
                distance = contourDistance;
        }
    if (resolveDistance(distance) == resolveDistance(shapeDistance))
        distance = shapeDistance;
    return distance;
}

template class OverlappingContourCombiner<TrueDistanceSelector>;
template class OverlappingContourCombiner<PseudoDistanceSelector>;
template class OverlappingContourCombiner<MultiDistanceSelector>;
template class OverlappingContourCombiner<MultiAndTrueDistanceSelector>;

}