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estimate-sdf-error.cpp
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estimate-sdf-error.cpp
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#include "estimate-sdf-error.h"
#include <cmath>
#include "arithmetics.hpp"
namespace msdfgen {
void scanlineSDF(Scanline &line, const BitmapConstRef<float, 1> &sdf, const Vector2 &scale, const Vector2 &translate, bool inverseYAxis, double y) {
if (!(sdf.width > 0 && sdf.height > 0))
return line.setIntersections(std::vector<Scanline::Intersection>());
double pixelY = clamp(scale.x*(y+translate.y)-.5, double(sdf.height-1));
if (inverseYAxis)
pixelY = sdf.height-1-pixelY;
int b = (int) floor(pixelY);
int t = b+1;
double bt = pixelY-b;
if (t >= sdf.height) {
b = sdf.height-1;
t = sdf.height-1;
bt = 1;
}
bool inside = false;
std::vector<Scanline::Intersection> intersections;
float lv, rv = mix(*sdf(0, b), *sdf(0, t), bt);
if ((inside = rv > .5f)) {
Scanline::Intersection intersection = { -1e240, 1 };
intersections.push_back(intersection);
}
for (int l = 0, r = 1; r < sdf.width; ++l, ++r) {
lv = rv;
rv = mix(*sdf(r, b), *sdf(r, t), bt);
if (lv != rv) {
double lr = double(.5f-lv)/double(rv-lv);
if (lr >= 0 && lr <= 1) {
Scanline::Intersection intersection = { (l+lr+.5)/scale.x-translate.x, sign(rv-lv) };
intersections.push_back(intersection);
}
}
}
#ifdef MSDFGEN_USE_CPP11
line.setIntersections((std::vector<Scanline::Intersection> &&) intersections);
#else
line.setIntersections(intersections);
#endif
}
template <int N>
void scanlineMSDF(Scanline &line, const BitmapConstRef<float, N> &sdf, const Vector2 &scale, const Vector2 &translate, bool inverseYAxis, double y) {
if (!(sdf.width > 0 && sdf.height > 0))
return line.setIntersections(std::vector<Scanline::Intersection>());
double pixelY = clamp(scale.x*(y+translate.y)-.5, double(sdf.height-1));
if (inverseYAxis)
pixelY = sdf.height-1-pixelY;
int b = (int) floor(pixelY);
int t = b+1;
double bt = pixelY-b;
if (t >= sdf.height) {
b = sdf.height-1;
t = sdf.height-1;
bt = 1;
}
bool inside = false;
std::vector<Scanline::Intersection> intersections;
float lv[3], rv[3];
rv[0] = mix(sdf(0, b)[0], sdf(0, t)[0], bt);
rv[1] = mix(sdf(0, b)[1], sdf(0, t)[1], bt);
rv[2] = mix(sdf(0, b)[2], sdf(0, t)[2], bt);
if ((inside = median(rv[0], rv[1], rv[2]) > .5f)) {
Scanline::Intersection intersection = { -1e240, 1 };
intersections.push_back(intersection);
}
for (int l = 0, r = 1; r < sdf.width; ++l, ++r) {
lv[0] = rv[0], lv[1] = rv[1], lv[2] = rv[2];
rv[0] = mix(sdf(r, b)[0], sdf(r, t)[0], bt);
rv[1] = mix(sdf(r, b)[1], sdf(r, t)[1], bt);
rv[2] = mix(sdf(r, b)[2], sdf(r, t)[2], bt);
Scanline::Intersection newIntersections[4];
int newIntersectionCount = 0;
for (int i = 0; i < 3; ++i) {
if (lv[i] != rv[i]) {
double lr = double(.5f-lv[i])/double(rv[i]-lv[i]);
if (lr >= 0 && lr <= 1) {
float v[3] = {
mix(lv[0], rv[0], lr),
mix(lv[1], rv[1], lr),
mix(lv[2], rv[2], lr)
};
if (median(v[0], v[1], v[2]) == v[i]) {
newIntersections[newIntersectionCount].x = (l+lr+.5)/scale.x-translate.x;
newIntersections[newIntersectionCount].direction = sign(rv[i]-lv[i]);
++newIntersectionCount;
}
}
}
}
// Sort new intersections
if (newIntersectionCount >= 2) {
if (newIntersections[0].x > newIntersections[1].x)
newIntersections[3] = newIntersections[0], newIntersections[0] = newIntersections[1], newIntersections[1] = newIntersections[3];
if (newIntersectionCount >= 3 && newIntersections[1].x > newIntersections[2].x) {
newIntersections[3] = newIntersections[1], newIntersections[1] = newIntersections[2], newIntersections[2] = newIntersections[3];
if (newIntersections[0].x > newIntersections[1].x)
newIntersections[3] = newIntersections[0], newIntersections[0] = newIntersections[1], newIntersections[1] = newIntersections[3];
}
}
for (int i = 0; i < newIntersectionCount; ++i) {
if ((newIntersections[i].direction > 0) == !inside) {
intersections.push_back(newIntersections[i]);
inside = !inside;
}
}
// Consistency check
float rvScalar = median(rv[0], rv[1], rv[2]);
if ((rvScalar > .5f) != inside && rvScalar != .5f && !intersections.empty()) {
intersections.pop_back();
inside = !inside;
}
}
#ifdef MSDFGEN_USE_CPP11
line.setIntersections((std::vector<Scanline::Intersection> &&) intersections);
#else
line.setIntersections(intersections);
#endif
}
void scanlineSDF(Scanline &line, const BitmapConstRef<float, 3> &sdf, const Vector2 &scale, const Vector2 &translate, bool inverseYAxis, double y) {
scanlineMSDF(line, sdf, scale, translate, inverseYAxis, y);
}
void scanlineSDF(Scanline &line, const BitmapConstRef<float, 4> &sdf, const Vector2 &scale, const Vector2 &translate, bool inverseYAxis, double y) {
scanlineMSDF(line, sdf, scale, translate, inverseYAxis, y);
}
template <int N>
double estimateSDFErrorInner(const BitmapConstRef<float, N> &sdf, const Shape &shape, const Vector2 &scale, const Vector2 &translate, int scanlinesPerRow, FillRule fillRule) {
if (sdf.width <= 1 || sdf.height <= 1 || scanlinesPerRow < 1)
return 0;
double subRowSize = 1./scanlinesPerRow;
double xFrom = .5/scale.x-translate.x;
double xTo = (sdf.width-.5)/scale.x-translate.x;
double overlapFactor = 1/(xTo-xFrom);
double error = 0;
Scanline refScanline, sdfScanline;
for (int row = 0; row < sdf.height-1; ++row) {
for (int subRow = 0; subRow < scanlinesPerRow; ++subRow) {
double bt = (subRow+.5)*subRowSize;
double y = (row+bt+.5)/scale.y-translate.y;
shape.scanline(refScanline, y);
scanlineSDF(sdfScanline, sdf, scale, translate, shape.inverseYAxis, y);
error += 1-overlapFactor*Scanline::overlap(refScanline, sdfScanline, xFrom, xTo, fillRule);
}
}
return error/((sdf.height-1)*scanlinesPerRow);
}
double estimateSDFError(const BitmapConstRef<float, 1> &sdf, const Shape &shape, const Vector2 &scale, const Vector2 &translate, int scanlinesPerRow, FillRule fillRule) {
return estimateSDFErrorInner(sdf, shape, scale, translate, scanlinesPerRow, fillRule);
}
double estimateSDFError(const BitmapConstRef<float, 3> &sdf, const Shape &shape, const Vector2 &scale, const Vector2 &translate, int scanlinesPerRow, FillRule fillRule) {
return estimateSDFErrorInner(sdf, shape, scale, translate, scanlinesPerRow, fillRule);
}
double estimateSDFError(const BitmapConstRef<float, 4> &sdf, const Shape &shape, const Vector2 &scale, const Vector2 &translate, int scanlinesPerRow, FillRule fillRule) {
return estimateSDFErrorInner(sdf, shape, scale, translate, scanlinesPerRow, fillRule);
}
}