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wg_engine: fix stroke mitter limit

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Change the appliense of stroke mitter limit as in SVG spec

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This commit is contained in:
Sergii Liebodkin 2024-06-20 14:47:49 +03:00 • committed by Hermet Park
parent 2c84033a07
commit 58705281cd
2 changed files with 43 additions and 53 deletions
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92
src/renderer/wg_engine/tvgWgGeometry.cpp
View file

@ -154,7 +154,7 @@ void WgPolyline::close()
bool WgPolyline::isClosed() const
{
return (pts.count >= 2) && (pts[0].dist2(pts.last()) == 0.0f);
return (pts.count >= 2) && (mathZero(pts[0].dist2(pts.last())));
}
@ -351,11 +351,41 @@ void WgGeometryData::appendStrokeDashed(const WgPolyline* polyline, const Render
}
void WgGeometryData::appendStrokeJoin(const WgPoint& v0, const WgPoint& v1, const WgPoint& v2, StrokeJoin join, float halfWidth, float miterLimit)
{
WgPoint dir0 = (v1 - v0).normal();
WgPoint dir1 = (v2 - v1).normal();
WgPoint nrm0 { +dir0.y, -dir0.x };
WgPoint nrm1 { +dir1.y, -dir1.x };
WgPoint offset0 = nrm0 * halfWidth;
WgPoint offset1 = nrm1 * halfWidth;
if (join == StrokeJoin::Round) {
appendCircle(v1, halfWidth);
} else if (join == StrokeJoin::Bevel) {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
} else if (join == StrokeJoin::Miter) {
WgPoint nrm = (nrm0 + nrm1);
if (!mathZero(dir0.x * dir1.y - dir0.y * dir1.x)) {
nrm.normalize();
float cosine = nrm.dot(nrm0);
float angle = std::acos(dir0.dot(dir1.negative()));
float miterRatio = 1.0f / (std::sin(angle) * 0.5);
if (miterRatio <= miterLimit) {
appendRect(v1 + nrm * (halfWidth / cosine), v1 + offset0, v1 + offset1, v1);
appendRect(v1 - nrm * (halfWidth / cosine), v1 - offset0, v1 - offset1, v1);
} else {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
}
}
}
}
void WgGeometryData::appendStroke(const WgPolyline* polyline, const RenderStroke *stroke)
{
assert(stroke);
assert(polyline);
float wdt = stroke->width / 2;
float wdt = stroke->width * 0.5f;
// single line sub-path
if (polyline->pts.count == 2) {
@ -375,37 +405,12 @@ void WgGeometryData::appendStroke(const WgPolyline* polyline, const RenderStroke
v1 - nrm0 * wdt + dir0 * wdt, v1 + nrm0 * wdt + dir0 * wdt
);
}
} else
// multi-lined sub-path
if (polyline->pts.count > 2) {
} else if (polyline->pts.count > 2) { // multi-lined sub-path
if (polyline->isClosed()) {
if (stroke->join == StrokeJoin::Round) {
appendCircle(polyline->pts[0], wdt);
} else {
float dist0 = polyline->dist.last();
float dist1 = polyline->dist[1];
WgPoint v0 = polyline->pts[polyline->pts.count - 2];
WgPoint v1 = polyline->pts[0];
WgPoint v2 = polyline->pts[1];
WgPoint dir0 = (v1 - v0) / dist0;
WgPoint dir1 = (v2 - v1) / dist1;
WgPoint nrm0 { +dir0.y, -dir0.x };
WgPoint nrm1 { +dir1.y, -dir1.x };
WgPoint offset0 = nrm0 * wdt;
WgPoint offset1 = nrm1 * wdt;
if (stroke->join == StrokeJoin::Bevel) {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
} else if (stroke->join == StrokeJoin::Miter) {
WgPoint nrm = (nrm0 + nrm1).normal();
float cosine = nrm.dot(nrm0);
if ((cosine != 0.0f) && (abs(cosine) != 1.0f) && (abs(wdt / cosine) <= stroke->miterlimit * 2)) {
appendRect(v1 + nrm * (wdt / cosine), v1 + offset0, v1 + offset1, v1 - nrm * (wdt / cosine));
} else {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
}
}
}
WgPoint v0 = polyline->pts[polyline->pts.count - 2];
WgPoint v1 = polyline->pts[0];
WgPoint v2 = polyline->pts[1];
appendStrokeJoin(v0, v1, v2, stroke->join, wdt, stroke->miterlimit);
} else {
// append first cap
WgPoint v0 = polyline->pts[0];
@ -445,27 +450,8 @@ void WgGeometryData::appendStroke(const WgPolyline* polyline, const RenderStroke
appendRect(v1 - offset1, v1 + offset1, v2 - offset1, v2 + offset1);
if (i > 0) {
if (stroke->join == StrokeJoin::Round) {
appendCircle(v1, wdt);
} else {
float dist0 = polyline->dist[i + 0];
WgPoint v0 = polyline->pts[i - 1];
WgPoint dir0 = (v1 - v0) / dist0;
WgPoint nrm0 { +dir0.y, -dir0.x };
WgPoint offset0 = nrm0 * wdt;
if (stroke->join == StrokeJoin::Bevel) {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
} else if (stroke->join == StrokeJoin::Miter) {
WgPoint nrm = (nrm0 + nrm1).normal();
float cosine = nrm.dot(nrm0);
if ((cosine != 0.0f) && (abs(cosine) < 1.0f) && (abs(wdt / cosine) <= stroke->miterlimit * 2)) {
appendRect(v1 + nrm * (wdt / cosine), v1 + offset0, v1 + offset1, v1);
appendRect(v1 - nrm * (wdt / cosine), v1 - offset0, v1 - offset1, v1);
} else {
appendRect(v1 - offset0, v1 + offset0, v1 - offset1, v1 + offset1);
}
}
}
WgPoint v0 = polyline->pts[i - 1];
appendStrokeJoin(v0, v1, v2, stroke->join, wdt, stroke->miterlimit);
}
}
}

4
src/renderer/wg_engine/tvgWgGeometry.h
View file

@ -51,9 +51,11 @@ public:
WgPoint negative() const { return {-x, -y}; }
inline void negate() { x = -x; y = -y; }
inline float length() const { return sqrt(x*x + y*y); }
inline float length2() const { return x*x + y*y; }
inline float dot(const WgPoint& p) const { return x * p.x + y * p.y; }
inline float dist(const WgPoint& p) const { return sqrt(dist2(p)); }
inline float dist2(const WgPoint& p) const { return ((p.x - x)*(p.x - x) + (p.y - y)*(p.y - y)); }
inline bool equal(const WgPoint& p) const { return mathEqual(x, p.x) && mathEqual(y, p.y); }
inline void normalize() { float rlen = 1.0f / length(); x *= rlen; y *= rlen; }
inline WgPoint normal() const { float rlen = 1.0f / length(); return { x * rlen, y * rlen }; }
inline WgPoint lerp(const WgPoint& p, float t) const { return { x + (p.x - x) * t, y + (p.y - y) * t }; };
@ -117,6 +119,8 @@ struct WgGeometryData
void appendBlitBox();
void appendMesh(const RenderMesh* rmesh);
void appendStrokeDashed(const WgPolyline* polyline, const RenderStroke *stroke);
void appendStrokeJoin(const WgPoint& v0, const WgPoint& v1, const WgPoint& v2,
StrokeJoin join, float halfWidth, float miterLimit);
void appendStroke(const WgPolyline* polyline, const RenderStroke *stroke);
};