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Revert "Revert "sw_engine: Increasing accuracy for dashed curves""
This reverts commit e49f9125b2
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e49f9125b2
commit
31b4428dd8
4 changed files with 73 additions and 43 deletions
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@ -29,7 +29,7 @@
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/* Internal Class Implementation */
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/************************************************************************/
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static float _lineLength(const Point& pt1, const Point& pt2)
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static float _lineLengthApprox(const Point& pt1, const Point& pt2)
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{
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/* approximate sqrt(x*x + y*y) using alpha max plus beta min algorithm.
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With alpha = 1, beta = 3/8, giving results with the largest error less
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@ -41,6 +41,59 @@ static float _lineLength(const Point& pt1, const Point& pt2)
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}
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static float _lineLength(const Point& pt1, const Point& pt2)
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{
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Point diff = {pt2.x - pt1.x, pt2.y - pt1.y};
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return sqrtf(diff.x * diff.x + diff.y * diff.y);
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}
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template<typename LengthFunc>
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float _bezLength(const Bezier& cur, LengthFunc lineLengthFunc)
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{
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Bezier left, right;
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auto len = lineLengthFunc(cur.start, cur.ctrl1) + lineLengthFunc(cur.ctrl1, cur.ctrl2) + lineLengthFunc(cur.ctrl2, cur.end);
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auto chord = lineLengthFunc(cur.start, cur.end);
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if (fabsf(len - chord) > BEZIER_EPSILON) {
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tvg::bezSplit(cur, left, right);
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return _bezLength(left, lineLengthFunc) + _bezLength(right, lineLengthFunc);
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}
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return len;
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}
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template<typename LengthFunc>
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float _bezAt(const Bezier& bz, float at, float length, LengthFunc lineLengthFunc)
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{
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auto biggest = 1.0f;
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auto smallest = 0.0f;
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auto t = 0.5f;
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//just in case to prevent an infinite loop
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if (at <= 0) return 0.0f;
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if (at >= length) return 1.0f;
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while (true) {
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auto right = bz;
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Bezier left;
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bezSplitLeft(right, t, left);
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length = _bezLength(left, lineLengthFunc);
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if (fabsf(length - at) < BEZIER_EPSILON || fabsf(smallest - biggest) < BEZIER_EPSILON) {
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break;
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}
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if (length < at) {
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smallest = t;
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t = (t + biggest) * 0.5f;
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} else {
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biggest = t;
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t = (smallest + t) * 0.5f;
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}
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}
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return t;
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}
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/************************************************************************/
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/* External Class Implementation */
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/************************************************************************/
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@ -48,7 +101,7 @@ static float _lineLength(const Point& pt1, const Point& pt2)
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namespace tvg
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{
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void bezSplit(const Bezier&cur, Bezier& left, Bezier& right)
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void bezSplit(const Bezier& cur, Bezier& left, Bezier& right)
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{
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auto c = (cur.ctrl1.x + cur.ctrl2.x) * 0.5f;
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left.ctrl1.x = (cur.start.x + cur.ctrl1.x) * 0.5f;
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@ -72,15 +125,13 @@ void bezSplit(const Bezier&cur, Bezier& left, Bezier& right)
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float bezLength(const Bezier& cur)
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{
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Bezier left, right;
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auto len = _lineLength(cur.start, cur.ctrl1) + _lineLength(cur.ctrl1, cur.ctrl2) + _lineLength(cur.ctrl2, cur.end);
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auto chord = _lineLength(cur.start, cur.end);
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return _bezLength(cur, _lineLength);
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}
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if (fabsf(len - chord) > BEZIER_EPSILON) {
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bezSplit(cur, left, right);
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return bezLength(left) + bezLength(right);
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}
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return len;
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float bezLengthApprox(const Bezier& cur)
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{
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return _bezLength(cur, _lineLengthApprox);
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}
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@ -110,31 +161,13 @@ void bezSplitLeft(Bezier& cur, float at, Bezier& left)
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float bezAt(const Bezier& bz, float at, float length)
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{
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auto biggest = 1.0f;
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auto smallest = 0.0f;
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auto t = 0.5f;
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return _bezAt(bz, at, length, _lineLength);
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}
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//just in case to prevent an infinite loop
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if (at <= 0) return 0.0f;
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if (at >= length) return 1.0f;
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while (true) {
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auto right = bz;
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Bezier left;
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bezSplitLeft(right, t, left);
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length = bezLength(left);
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if (fabsf(length - at) < BEZIER_EPSILON || fabsf(smallest - biggest) < BEZIER_EPSILON) {
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break;
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}
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if (length < at) {
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smallest = t;
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t = (t + biggest) * 0.5f;
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} else {
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biggest = t;
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t = (smallest + t) * 0.5f;
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}
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}
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return t;
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float bezAtApprox(const Bezier& bz, float at, float length)
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{
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return _bezAt(bz, at, length, _lineLengthApprox);
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}
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@ -44,6 +44,8 @@ void bezSplitAt(const Bezier& cur, float at, Bezier& left, Bezier& right);
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Point bezPointAt(const Bezier& bz, float t);
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float bezAngleAt(const Bezier& bz, float t);
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float bezLengthApprox(const Bezier& cur);
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float bezAtApprox(const Bezier& bz, float at, float length);
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}
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#endif //_TVG_BEZIER_H_
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@ -158,7 +158,7 @@ struct LottieVectorFrame
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if (hasTangent) {
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Bezier bz = {value, value + outTangent, next->value + inTangent, next->value};
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t = bezAt(bz, t * length, length);
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t = bezAtApprox(bz, t * length, length);
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return bezPointAt(bz, t);
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} else {
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return mathLerp(value, next->value, t);
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@ -171,14 +171,14 @@ struct LottieVectorFrame
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auto t = (frameNo - no) / (next->no - no);
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if (interpolator) t = interpolator->progress(t);
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Bezier bz = {value, value + outTangent, next->value + inTangent, next->value};
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t = bezAt(bz, t * length, length);
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t = bezAtApprox(bz, t * length, length);
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return -bezAngleAt(bz, t);
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}
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void prepare(LottieVectorFrame* next)
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{
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Bezier bz = {value, value + outTangent, next->value + inTangent, next->value};
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length = bezLength(bz);
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length = bezLengthApprox(bz);
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}
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};
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@ -37,13 +37,8 @@ struct Line
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static float _lineLength(const Point& pt1, const Point& pt2)
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{
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/* approximate sqrt(x*x + y*y) using alpha max plus beta min algorithm.
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With alpha = 1, beta = 3/8, giving results with the largest error less
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than 7% compared to the exact value. */
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Point diff = {pt2.x - pt1.x, pt2.y - pt1.y};
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if (diff.x < 0) diff.x = -diff.x;
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if (diff.y < 0) diff.y = -diff.y;
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return (diff.x > diff.y) ? (diff.x + diff.y * 0.375f) : (diff.y + diff.x * 0.375f);
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return sqrtf(diff.x * diff.x + diff.y * diff.y);
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}
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@ -388,7 +383,7 @@ static float _outlineLength(const RenderShape* rshape)
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break;
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}
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case PathCommand::CubicTo: {
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length += bezLength({*(pts - 1), *pts, *(pts + 1), *(pts + 2)});
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length += bezLengthApprox({*(pts - 1), *pts, *(pts + 1), *(pts + 2)});
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pts += 3;
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break;
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}
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