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| using System; |
| using System.Drawing; |
| |
| namespace Contours { |
| public static class Geometry { |
| public enum IntersectionType { |
| None, |
| Cross, |
| Identical, |
| Inverted, |
| Touch_a0, |
| Touch_a1, |
| Touch_b0, |
| Touch_b1, |
| Touch_a0_b0, |
| Touch_a0_b1, |
| Touch_a1_b0, |
| Touch_a1_b1, |
| Along_a0_b0_a1_b1, |
| Along_a0_b0_b1_a1, |
| Along_a0_b1_a1_b0, |
| Along_a0_b1_b0_a1, |
| Along_b0_a0_a1_b1, |
| Along_b0_a0_b1_a1, |
| Along_b1_a0_a1_b0, |
| Along_b1_a0_b0_a1 |
| } |
| |
| |
| public static int comparePointsAtLine(Point a0, Point a1, Point base0, Point base1) { |
| if (base0.X < base1.X && a0.X < a1.X) return -1; |
| if (base0.X < base1.X && a1.X < a0.X) return 1; |
| if (base1.X < base0.X && a0.X < a1.X) return 1; |
| if (base1.X < base0.X && a1.X < a0.X) return -1; |
| if (base0.Y < base1.Y && a0.Y < a1.Y) return -1; |
| if (base0.Y < base1.Y && a1.Y < a0.Y) return 1; |
| if (base1.Y < base0.Y && a0.Y < a1.Y) return 1; |
| if (base1.Y < base0.Y && a1.Y < a0.Y) return -1; |
| return 0; |
| } |
| |
| public static bool isPointAtLine(Point p, Point p0, Point p1) { |
| if (p == p0 || p == p1) |
| return true; |
| if (p0 == p1) |
| return false; |
| if ((long)(p.Y-p0.Y)*(long)(p1.X-p0.X) != (long)(p.X-p0.X)*(long)(p1.Y-p0.Y)) |
| return false; |
| if (p1.X > p0.X) |
| return p.X >= p0.X && p.X <= p1.X; |
| if (p1.X < p0.X) |
| return p.X >= p1.X && p.X <= p0.X; |
| if (p1.Y > p0.Y) |
| return p.Y >= p0.Y && p.Y <= p1.Y; |
| |
| return p.Y >= p1.Y && p.Y <= p0.Y; |
| } |
| |
| public static IntersectionType findIntersection(Point a0, Point a1, Point b0, Point b1, out Point c) { |
| c = new Point(0, 0); |
| Point da = new Point(a1.X - a0.X, a1.Y - a0.Y); |
| Point db = new Point(b1.X - b0.X, b1.Y - b0.Y); |
| |
| if (a0.X == b0.X && a0.Y == b0.Y && a1.X == b1.X && a1.Y == b1.Y) |
| return IntersectionType.Identical; |
| |
| if (a0.X == b1.X && a0.Y == b1.Y && a1.X == b0.X && a1.Y == b0.Y) |
| return IntersectionType.Inverted; |
| |
| long divider = (long)da.X*(long)db.Y - (long)db.X*(long)da.Y; |
| if (divider == 0) { |
| if ((long)da.X*(long)(b0.Y - a0.Y) != (long)da.Y*(long)(b0.X - a0.X)) |
| return IntersectionType.None; |
| |
| int a0b0 = comparePointsAtLine(a0, b0, a0, a1); |
| int a0b1 = comparePointsAtLine(a0, b1, a0, a1); |
| int a1b0 = comparePointsAtLine(a1, b0, a0, a1); |
| int a1b1 = comparePointsAtLine(a1, b1, a0, a1); |
| int b0b1 = comparePointsAtLine(b0, b1, a0, a1); |
| int b0a0 = -a0b0; |
| int b0a1 = -a1b0; |
| int b1a0 = -a0b1; |
| int b1a1 = -a1b1; |
| int b1b0 = -b0b1; |
| |
| |
| if (a1b0 == 0 && b0b1 <= 0) |
| return IntersectionType.Touch_a1_b0; |
| |
| if (a1b1 == 0 && b1b0 <= 0) |
| return IntersectionType.Touch_a1_b1; |
| |
| if (b0b1 <= 0 && b1a0 == 0) |
| return IntersectionType.Touch_a0_b1; |
| |
| if (b1b0 <= 0 && b0a0 == 0) |
| return IntersectionType.Touch_a0_b0; |
| |
| if (a0b0 <= 0 && b0a1 <= 0 && a1b1 <= 0) |
| return IntersectionType.Along_a0_b0_a1_b1; |
| if (a0b0 <= 0 && b0b1 <= 0 && b1a1 <= 0) |
| return IntersectionType.Along_a0_b0_b1_a1; |
| if (a0b1 <= 0 && b1a1 <= 0 && a1b0 <= 0) |
| return IntersectionType.Along_a0_b1_a1_b0; |
| if (a0b1 <= 0 && b1b0 <= 0 && b0a1 <= 0) |
| return IntersectionType.Along_a0_b1_b0_a1; |
| if (b0a0 <= 0 && a1b1 <= 0) |
| return IntersectionType.Along_b0_a0_a1_b1; |
| if (b0a0 <= 0 && a0b1 <= 0 && b1a1 <= 0) |
| return IntersectionType.Along_b0_a0_b1_a1; |
| if (b1a0 <= 0 && a1b0 <= 0) |
| return IntersectionType.Along_b1_a0_a1_b0; |
| if (b1a0 <= 0 && a0b0 <= 0 && b0a1 <= 0) |
| return IntersectionType.Along_b1_a0_b0_a1; |
| |
| return IntersectionType.None; |
| } |
| |
| if (a0.X == b0.X && a0.Y == b0.Y) |
| return IntersectionType.Touch_a0_b0; |
| if (a0.X == b1.X && a0.Y == b1.Y) |
| return IntersectionType.Touch_a0_b1; |
| if (a1.X == b0.X && a1.Y == b0.Y) |
| return IntersectionType.Touch_a1_b0; |
| if (a1.X == b1.X && a1.Y == b1.Y) |
| return IntersectionType.Touch_a1_b1; |
| |
| long numeratorX = (long)da.X*((long)b1.Y*(long)b0.X - (long)b0.Y*(long)b1.X) |
| - (long)db.X*((long)a1.Y*(long)a0.X - (long)a0.Y*(long)a1.X); |
| long numeratorY = (long)db.Y*((long)a1.X*(long)a0.Y - (long)a0.X*(long)a1.Y) |
| - (long)da.Y*((long)b1.X*(long)b0.Y - (long)b0.X*(long)b1.Y); |
| Point p = new Point((int)(numeratorX/divider), (int)(numeratorY/divider)); |
| if ( comparePointsAtLine(p, a0, a0, a1) < 0 |
| || comparePointsAtLine(p, a1, a0, a1) > 0 |
| || comparePointsAtLine(p, b0, b0, b1) < 0 |
| || comparePointsAtLine(p, b1, b0, b1) > 0 ) |
| return IntersectionType.None; |
| |
| if (p.X == a0.X && p.Y == a0.Y) |
| return IntersectionType.Touch_a0; |
| if (p.X == a1.X && p.Y == a1.Y) |
| return IntersectionType.Touch_a1; |
| if (p.X == b0.X && p.Y == b0.Y) |
| return IntersectionType.Touch_b0; |
| if (p.X == b1.X && p.Y == b1.Y) |
| return IntersectionType.Touch_b1; |
| |
| c = p; |
| return IntersectionType.Cross; |
| } |
| |
| public static bool isCCW(Point a, Point b, Point c) { |
| long d = (long)a.X*(long)c.Y - (long)a.Y*(long)c.X; |
| |
| if (d > 0) |
| return (long)a.X*(long)b.Y >= (long)a.Y*(long)b.X |
| && (long)c.X*(long)b.Y <= (long)c.Y*(long)b.X; |
| |
| if (d < 0) |
| return (long)a.X*(long)b.Y >= (long)a.Y*(long)b.X |
| || (long)c.X*(long)b.Y <= (long)c.Y*(long)b.X; |
| |
| if ((a.X >= 0) != (c.X >= 0) || (a.Y >= 0) != (c.Y >= 0)) |
| return (long)a.X*(long)b.Y >= (long)a.Y*(long)b.X; |
| |
| return true; |
| } |
| |
| public static bool isCCW(Point center, Point a, Point b, Point c) { |
| return isCCW( |
| new Point(a.X - center.X, a.Y - center.Y), |
| new Point(b.X - center.X, b.Y - center.Y), |
| new Point(c.X - center.X, c.Y - center.Y) ); |
| } |
| |
| public static void makeLongestLine(Point p0, ref Point p1) { |
| int MaxValue = int.MaxValue >> 1; |
| Point direction = new Point(p1.X - p0.X, p1.Y - p0.Y); |
| int amplifierX = |
| direction.X > 0 ? (MaxValue - p0.X)/direction.X + 1 |
| : direction.X < 0 ? (MaxValue + p0.X)/(-direction.X) + 1 |
| : int.MaxValue; |
| int amplifierY = |
| direction.Y > 0 ? (MaxValue - p0.Y)/direction.Y + 1 |
| : direction.Y < 0 ? (MaxValue + p0.Y)/(-direction.Y) + 1 |
| : int.MaxValue; |
| int amplifier = Math.Min(amplifierX, amplifierY); |
| p1 = new Point( |
| p0.X + direction.X*amplifier, |
| p0.Y + direction.Y*amplifier ); |
| } |
| |
| } |
| } |
| |