From 3d0d8e814fd55b9f65b74478384cf990d509ca30 Mon Sep 17 00:00:00 2001 From: Ineiev Date: Thu, 12 Nov 2009 08:45:25 +0300 Subject: [PATCH 2/3] fix ArcArcIntersect --- src/find.c | 180 +++++++++++++++++++++++++++++++++++++++-------------------- 1 files changed, 119 insertions(+), 61 deletions(-) diff --git a/src/find.c b/src/find.c index b24512a..3bffd6f 100644 --- a/src/find.c +++ b/src/find.c @@ -1327,11 +1327,45 @@ PVTouchesLine (LineTypePtr line) return (False); } +static int +radius_crosses_arc (float x, float y, ArcTypePtr arc) +{ + float alpha = atan2 (y - arc->Y, -x + arc->X) * 180 / M_PI, start, delta; + + start = (float) fmod (arc->StartAngle, 360); + delta = arc->Delta; + if (alpha < 0) + alpha += 360; + if (start < 0) + start += 360; + if (delta < 0) + { + start += delta; + delta = -delta; + } + return (start < alpha && start + delta > alpha); +} +/* reduce arc start angle and delta to 0..360 */ +static void +normalize_angles (int *sa, int *d) +{ + if (*d < 0) + { + *sa = *sa + *d; + *d = - *d; + } + if (*d > 360) /* full circle */ + *d = 360; + if (*sa < 0) + *sa = 360 - ((-*sa) % 360); + if (*sa >= 360) + *sa %= 360; +} /* --------------------------------------------------------------------------- * check if two arcs intersect * first we check for circle intersections, * then find the actual points of intersection - * and test them to see if they are on both arcs + * and test them to see if they are on arcs * * consider a, the distance from the center of arc 1 * to the point perpendicular to the intersecting points. @@ -1355,18 +1389,29 @@ PVTouchesLine (LineTypePtr line) static Boolean ArcArcIntersect (ArcTypePtr Arc1, ArcTypePtr Arc2) { - register float x, y, dx, dy, r1, r2, a, d, l, t, t2; - register LocationType pdx, pdy; + float x, y, dx, dy, r1, r2, a, d, l, t, t1, t2, dl; + LocationType pdx, pdy; BoxTypePtr box; - BoxType box1, box2; pdx = Arc2->X - Arc1->X; pdy = Arc2->Y - Arc1->Y; l = pdx * pdx + pdy * pdy; t = MAX (0.5 * Arc1->Thickness + fBloat, 0.0); t2 = 0.5 * Arc2->Thickness; + t1 = MAX (t2 + fBloat, 0.0); + /* try the end points first */ + box = GetArcEnds (Arc1); + if (IsPointOnArc ((float) box->X1, (float) box->Y1, t, Arc2) + || IsPointOnArc ((float) box->X2, (float) box->Y2, t, Arc2)) + return (True); + + box = GetArcEnds (Arc2); + if (IsPointOnArc ((float) box->X1, (float) box->Y1, t1, Arc1) + || IsPointOnArc ((float) box->X2, (float) box->Y2, t1, Arc1)) + return (True); + /* concentric arcs, simpler intersection conditions */ - if (l == 0.0) + if (l < 0.5) { if ((Arc1->Width - t >= Arc2->Width - t2 && Arc1->Width - t <= @@ -1374,36 +1419,66 @@ ArcArcIntersect (ArcTypePtr Arc1, ArcTypePtr Arc2) || (Arc1->Width + t >= Arc2->Width - t2 && Arc1->Width + t <= Arc2->Width + t2)) { - if ((Arc2->BoundingBox.X1 + - MAX (Arc2->Thickness + Bloat, - 0) >= Arc1->BoundingBox.X1 - && Arc2->BoundingBox.X1 <= - Arc1->BoundingBox.X2 - && Arc2->BoundingBox.Y1 + - MAX (Arc2->Thickness + Bloat, - 0) >= Arc1->BoundingBox.Y1 - && Arc2->BoundingBox.Y1 <= - Arc1->BoundingBox.Y2) - || (Arc2->BoundingBox.X2 + - MAX (Arc2->Thickness + - Bloat, - 0) >= - Arc1->BoundingBox.X1 - && Arc2->BoundingBox.X2 <= - Arc1->BoundingBox.X2 - && Arc2->BoundingBox.Y2 + - MAX (Arc2->Thickness + - Bloat, - 0) >= - Arc1->BoundingBox.Y1 - && Arc2->BoundingBox.Y2 <= Arc1->BoundingBox.Y2)) - return (True); + int sa1 = Arc1->StartAngle, d1 = Arc1->Delta; + int sa2 = Arc2->StartAngle, d2 = Arc2->Delta; + /* NB the endpoints have already been checked, + so we just compare the angles */ + + normalize_angles (&sa1, &d1); + normalize_angles (&sa2, &d2); + /* cases like sa1 == sa2 are catched when checking the endpoints */ + if (sa1 > sa2) + { + if (sa1 < sa2 + d2) + return (True); + if (sa1 + d1 - 360 > sa2) + return (True); + } + if (sa2 > sa1) + { + if (sa2 < sa1 + d1) + return (True); + if (sa2 + d2 - 360 > sa1) + return (True); + } } return (False); } - r1 = Arc1->Width + t; + r1 = Arc1->Width; + r2 = Arc2->Width; + dl = sqrt (l); + if (dl > r1 + r2 || dl + r1 < r2 + || dl + r2 < r1) /* arcs centerlines are too far or too near */ + { + /* check the nearst to the other arc center point */ + dx = pdx * r1 / dl; + dy = pdy * r1 / dl; + if (dl + r1 < r2) /* Arc1 inside Arc2 */ + { + dx = - dx; + dy = - dy; + } + + if (radius_crosses_arc (Arc1->X + dx, Arc1->Y + dy, Arc1) + && IsPointOnArc (Arc1->X + dx, Arc1->Y + dy, t, Arc2)) + return (True); + + dx = - pdx * r2 / dl; + dy = - pdy * r2 / dl; + if (dl + r2 < r1) /* Arc2 inside Arc1 */ + { + dx = - dx; + dy = - dy; + } + + if (radius_crosses_arc (Arc2->X + dx, Arc2->Y + dy, Arc2) + && IsPointOnArc (Arc2->X + dx, Arc2->Y + dy, t1, Arc1)) + return (True); + + return (False); + } + r1 *= r1; - r2 = Arc2->Width + t2; r2 *= r2; a = 0.5 * (r1 - r2 + l) / l; r1 = r1 / l; @@ -1411,46 +1486,29 @@ ArcArcIntersect (ArcTypePtr Arc1, ArcTypePtr Arc2) d = r1 - a * a + 1e-5; /* the circles are too far apart to touch */ if (d < 0) - return (False); + { + /* this may not occur */ + return (False); + } d = sqrt (d); x = Arc1->X + a * pdx; y = Arc1->Y + a * pdy; dx = d * pdx; dy = d * pdy; - if (x + dy >= Arc1->BoundingBox.X1 - && x + dy <= Arc1->BoundingBox.X2 - && y - dx >= Arc1->BoundingBox.Y1 - && y - dx <= Arc1->BoundingBox.Y2 - && x + dy >= Arc2->BoundingBox.X1 - && x + dy <= Arc2->BoundingBox.X2 - && y - dx >= Arc2->BoundingBox.Y1 && y - dx <= Arc2->BoundingBox.Y2) + if (radius_crosses_arc (x + dy, y - dx, Arc1) + && IsPointOnArc (x + dy, y - dx, t, Arc2)) return (True); - - if (x - dy >= Arc1->BoundingBox.X1 - && x - dy <= Arc1->BoundingBox.X2 - && y + dx >= Arc1->BoundingBox.Y1 - && y + dx <= Arc1->BoundingBox.Y2 - && x - dy >= Arc2->BoundingBox.X1 - && x - dy <= Arc2->BoundingBox.X2 - && y + dx >= Arc2->BoundingBox.Y1 && y + dx <= Arc2->BoundingBox.Y2) + if (radius_crosses_arc (x + dy, y - dx, Arc2) + && IsPointOnArc (x + dy, y - dx, t1, Arc1)) return (True); - /* try the end points in case the ends don't actually pierce the outer radii */ - box = GetArcEnds (Arc1); - box1 = *box; - box = GetArcEnds (Arc2); - box2 = *box; - if (IsPointOnArc - ((float) box1.X1, (float) box1.Y1, t, - Arc2) || IsPointOnArc ((float) box1.X2, (float) box1.Y2, t, Arc2)) + if (radius_crosses_arc (x - dy, y + dx, Arc1) + && IsPointOnArc (x - dy, y + dx, t, Arc2)) return (True); - - if (IsPointOnArc - ((float) box2.X1, (float) box2.Y1, - MAX (t2 + fBloat, 0.0), Arc1) - || IsPointOnArc ((float) box2.X2, - (float) box2.Y2, MAX (t2 + fBloat, 0.0), Arc1)) + if (radius_crosses_arc (x - dy, y + dx, Arc2) + && IsPointOnArc (x - dy, y + dx, t1, Arc1)) return (True); + return (False); } -- 1.6.5.2