git_clone/thorvg
1
0
Fork 0
mirror of https://github.com/thorvg/thorvg.git synced 2025-07-23 14:48:24 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

lottie: ensure proper shape closure

Browse source 
- Ensured proper closure of star and polygon shapes.
The start and end points now match - in cases with
degenerate bezier curves, the second-to-last point
is also aligned.
Proper shape closure is necessary for modifiers like
offset (future pucker bloat). If the start and end
points aren’t equal (within the comparison function’s
precision), the shape will be closed with a straight
line - and during offsetting, that line will become
visible, even though it’s not intended.

- Use of the internal _zero() function for point equality check
in modifiers algs led to incorrect results when p2.x or p2.y
was zero (division by zero).
The intent was to treat nearly identical points as equal, but
this approach was flawed - at the modifier stage, it’s no longer
possible to tell if small gaps are intentional or just due to
limited numerical precision (as seen for example in the difference
between the start and end points of star/polygon shapes).
This commit is contained in:
Mira Grudzinska 2025-06-18 23:55:28 +02:00
parent 68f01c85fa
commit 955c5b60b2
2 changed files with 14 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
src/loaders/lottie/tvgLottieBuilder.cpp
View file

@ -581,6 +581,13 @@ void LottieBuilder::updatePath(LottieGroup* parent, LottieObject** child, float
}
static void _close(Array<Point>& pts, const Point& p, bool round)
{
if (round && tvg::zero(pts.last() - pts[pts.count - 2])) pts[pts.count - 2] = p;
pts.last() = p;
}
static void _updateStar(TVG_UNUSED LottieGroup* parent, LottiePolyStar* star, Matrix* transform, const LottieRoundnessModifier* roundness, const LottieOffsetModifier* offsetPath, float frameNo, Shape* merging, LottieExpressions* exps)
{
static constexpr auto POLYSTAR_MAGIC_NUMBER = 0.47829f / 0.28f;
@ -695,6 +702,8 @@ static void _updateStar(TVG_UNUSED LottieGroup* parent, LottiePolyStar* star, Ma
angle += dTheta * direction;
longSegment = !longSegment;
}
//ensure proper shape closure - important for modifiers that behave differently for degenerate (linear) vs curved cubics
_close(P(shape)->rs.path.pts, in, hasRoundness);
shape->close();
if (roundedCorner) {
@ -777,6 +786,8 @@ static void _updatePolygon(LottieGroup* parent, LottiePolyStar* star, Matrix* tr
}
angle += anglePerPoint * direction;
}
//ensure proper shape closure - important for modifiers that behave differently for degenerate (linear) vs curved cubics
_close(P(shape)->rs.path.pts, in, hasRoundness);
shape->close();
if (roundedCorner) {

13
src/loaders/lottie/tvgLottieModifier.cpp
View file

@ -46,16 +46,9 @@ static void _roundCorner(Array<PathCommand>& cmds, Array<Point>& pts, const Poin
}
static bool _zero(const Point& p1, const Point& p2)
{
constexpr float epsilon = 1e-3f;
return fabsf(p1.x / p2.x - 1.0f) < epsilon && fabsf(p1.y / p2.y - 1.0f) < epsilon;
}
static bool _intersect(const Line& line1, const Line& line2, Point& intersection, bool& inside)
{
if (_zero(line1.pt2, line2.pt1)) {
if (tvg::zero(line1.pt2 - line2.pt1)) {
intersection = line1.pt2;
inside = true;
return true;
@ -162,7 +155,7 @@ void LottieOffsetModifier::line(const PathCommand* inCmds, uint32_t inCmdsCnt, c
Line nextLine = state.firstLine;
if (inCmds[currentCmd + 1] == PathCommand::LineTo) nextLine = _offset(inPts[currentPt + degenerated], inPts[currentPt + 1 + degenerated], offset);
else if (inCmds[currentCmd + 1] == PathCommand::CubicTo) nextLine = _offset(inPts[currentPt + 1 + degenerated], inPts[currentPt + 2 + degenerated], offset);
else if (inCmds[currentCmd + 1] == PathCommand::Close && !_zero(inPts[currentPt + degenerated], inPts[state.movetoInIndex + degenerated]))
else if (inCmds[currentCmd + 1] == PathCommand::Close && !tvg::zero(inPts[currentPt + degenerated] - inPts[state.movetoInIndex + degenerated]))
nextLine = _offset(inPts[currentPt + degenerated], inPts[state.movetoInIndex + degenerated], offset);
corner(state.line, nextLine, state.movetoOutIndex, inCmds[currentCmd + 1] == PathCommand::Close, outCmds, outPts);
@ -368,7 +361,7 @@ bool LottieOffsetModifier::modifyPath(const PathCommand* inCmds, uint32_t inCmds
iPt += 3;
}
else {
if (!_zero(inPts[iPt - 1], inPts[state.movetoInIndex])) {
if (!tvg::zero(inPts[iPt - 1] - inPts[state.movetoInIndex])) {
outCmds.push(PathCommand::LineTo);
corner(state.line, state.firstLine, state.movetoOutIndex, true, outCmds, outPts);
}