126 lines
3.9 KiB
C++
126 lines
3.9 KiB
C++
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#include "Scanline.h"
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#include <cstdlib>
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#include "arithmetics.hpp"
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namespace msdfgen {
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static int compareIntersections(const void *a, const void *b) {
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return sign(reinterpret_cast<const Scanline::Intersection *>(a)->x-reinterpret_cast<const Scanline::Intersection *>(b)->x);
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}
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bool interpretFillRule(int intersections, FillRule fillRule) {
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switch (fillRule) {
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case FILL_NONZERO:
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return intersections != 0;
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case FILL_ODD:
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return intersections&1;
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case FILL_POSITIVE:
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return intersections > 0;
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case FILL_NEGATIVE:
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return intersections < 0;
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}
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return false;
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}
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double Scanline::overlap(const Scanline &a, const Scanline &b, double xFrom, double xTo, FillRule fillRule) {
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double total = 0;
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bool aInside = false, bInside = false;
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int ai = 0, bi = 0;
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double ax = !a.intersections.empty() ? a.intersections[ai].x : xTo;
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double bx = !b.intersections.empty() ? b.intersections[bi].x : xTo;
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while (ax < xFrom || bx < xFrom) {
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double xNext = min(ax, bx);
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if (ax == xNext && ai < (int) a.intersections.size()) {
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aInside = interpretFillRule(a.intersections[ai].direction, fillRule);
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ax = ++ai < (int) a.intersections.size() ? a.intersections[ai].x : xTo;
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}
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if (bx == xNext && bi < (int) b.intersections.size()) {
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bInside = interpretFillRule(b.intersections[bi].direction, fillRule);
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bx = ++bi < (int) b.intersections.size() ? b.intersections[bi].x : xTo;
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}
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}
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double x = xFrom;
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while (ax < xTo || bx < xTo) {
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double xNext = min(ax, bx);
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if (aInside == bInside)
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total += xNext-x;
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if (ax == xNext && ai < (int) a.intersections.size()) {
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aInside = interpretFillRule(a.intersections[ai].direction, fillRule);
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ax = ++ai < (int) a.intersections.size() ? a.intersections[ai].x : xTo;
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}
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if (bx == xNext && bi < (int) b.intersections.size()) {
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bInside = interpretFillRule(b.intersections[bi].direction, fillRule);
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bx = ++bi < (int) b.intersections.size() ? b.intersections[bi].x : xTo;
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}
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x = xNext;
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}
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if (aInside == bInside)
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total += xTo-x;
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return total;
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}
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Scanline::Scanline() : lastIndex(0) { }
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void Scanline::preprocess() {
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lastIndex = 0;
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if (!intersections.empty()) {
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qsort(&intersections[0], intersections.size(), sizeof(Intersection), compareIntersections);
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int totalDirection = 0;
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for (std::vector<Intersection>::iterator intersection = intersections.begin(); intersection != intersections.end(); ++intersection) {
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totalDirection += intersection->direction;
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intersection->direction = totalDirection;
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}
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}
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}
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void Scanline::setIntersections(const std::vector<Intersection> &intersections) {
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this->intersections = intersections;
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preprocess();
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}
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#ifdef MSDFGEN_USE_CPP11
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void Scanline::setIntersections(std::vector<Intersection> &&intersections) {
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this->intersections = (std::vector<Intersection> &&) intersections;
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preprocess();
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}
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#endif
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int Scanline::moveTo(double x) const {
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if (intersections.empty())
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return -1;
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int index = lastIndex;
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if (x < intersections[index].x) {
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do {
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if (index == 0) {
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lastIndex = 0;
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return -1;
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}
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--index;
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} while (x < intersections[index].x);
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} else {
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while (index < (int) intersections.size()-1 && x >= intersections[index+1].x)
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++index;
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}
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lastIndex = index;
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return index;
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}
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int Scanline::countIntersections(double x) const {
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return moveTo(x)+1;
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}
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int Scanline::sumIntersections(double x) const {
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int index = moveTo(x);
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if (index >= 0)
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return intersections[index].direction;
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return 0;
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}
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bool Scanline::filled(double x, FillRule fillRule) const {
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return interpretFillRule(sumIntersections(x), fillRule);
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}
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}
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