godot/thirdparty/msdfgen/core/Scanline.cpp
2024-03-13 09:12:50 +02:00

126 lines
3.9 KiB
C++

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