Fix infinite loops for huge non-cartesian coordinates.

Author: awulkiew

Visual_Studio_2017/GraphicalDebugging/Geometry.cs

@@ -401,7 +401,7 @@ private static bool IntersectsAntimeridian(Point p1, Point p2, Unit unit)
                 double x1 = NormalizedAngleSigned(p1[0], unit);
                 double x2 = NormalizedAngleSigned(p2[0], unit);
                 double dist = x2 - x1;
-                double pi = HalfAngle(unit);
+                double pi = StraightAngle(unit);
                 return dist < -pi || pi < dist;
             }
         }
@@ -416,7 +416,7 @@ public static double NearestAntimeridian(double x, int dir, Unit unit)
             }
             else
             {
-                double pi = HalfAngle(unit);
+                double pi = StraightAngle(unit);
                 double ax = Math.Abs(x);
                 double periods = (ax - pi) / (2 * pi);
                 int calcDir = x < 0 ? -dir : dir;
@@ -487,7 +487,7 @@ public static Box EnvelopeAngle(Box box, Unit unit)
             Point p0 = Normalized(box.Min, unit);
             Point p1 = Normalized(box.Max, unit);
             if (p1[0] < p0[0])
-                p1[0] += 2 * HalfAngle(unit);
+                p1[0] += FullAngle(unit);
             return Envelope(p0, p1);
         }
 
@@ -578,12 +578,13 @@ public static void ExpandAngle(Box box, Box b, Unit unit)
             double xmax1 = NormalizedAngleSigned(box.Max[0], unit);
             double xmin2 = NormalizedAngleSigned(b.Min[0], unit);
             double xmax2 = NormalizedAngleSigned(b.Max[0], unit);
+
+            double twoPi = FullAngle(unit);
             if (xmax1 < xmin1)
-                xmax1 += 2 * HalfAngle(unit);
+                xmax1 += twoPi;
             if (xmax2 < xmin2)
-                xmax2 += 2 * HalfAngle(unit);
+                xmax2 += twoPi;
 
-            double twoPi = 2 * HalfAngle(unit);
             double left_dist = NormalizedAngleSigned(xmin1 - xmin2, unit);
             double right_dist = NormalizedAngleSigned(xmax2 - xmax1, unit);
             if (left_dist >= 0 && right_dist >= 0)
@@ -650,15 +651,15 @@ public static Point Normalized(Point p, Unit unit)
 
         public static double NormalizedAngleSigned(double x, Unit unit)
         {
-            double pi = HalfAngle(unit);
+            double pi = StraightAngle(unit);
             while (x < -pi) x += 2 * pi;
             while (x > pi) x -= 2 * pi;
             return x;
         }
 
         public static double NormalizedAngleUnsigned(double x, Unit unit)
         {
-            double pi = HalfAngle(unit);
+            double pi = StraightAngle(unit);
             while (x < 0) x += 2 * pi;
             while (x > 2 * pi) x -= 2 * pi;
             return x;
@@ -679,14 +680,24 @@ private static void NormalizeAngle(Box b, Unit unit)
             NormalizeAngle(b.Min, unit);
             NormalizeAngle(b.Max, unit);
             if (b.Min[0] > b.Max[0])
-                b.Max[0] += 2 * HalfAngle(unit);
+                b.Max[0] += FullAngle(unit);
         }*/
 
-        public static double HalfAngle(Unit unit)
+        public static double StraightAngle(Unit unit)
         {
             return unit == Unit.Degree ? 180 : Math.PI;
         }
 
+        public static double FullAngle(Unit unit)
+        {
+            return unit == Unit.Degree ? 360 : (2.0 * Math.PI);
+        }
+
+        public static double RightAngle(Unit unit)
+        {
+            return unit == Unit.Degree ? 90 : (0.5 * Math.PI);
+        }
+
         public static double ToRadian(double angle, Unit unit)
         {
             return unit == Unit.Degree ? (angle * Math.PI / 180.0) : angle;
@@ -802,7 +813,7 @@ public static Point[] SphericalDensify(Point p0, Point p1, double length, Unit u
             }
             else
             {
-                double halfPi = HalfAngle(unit) / 2;
+                double halfPi = RightAngle(unit);
                 if (Equals(p0[1], halfPi))
                     axis = new Point(0, 1, 0);
                 else if (Equals(p0[1], -halfPi))

Visual_Studio_2017/GraphicalDebugging/Util.cs

@@ -366,5 +366,13 @@ public static bool IsOk<T1, T2, T3, T4>(T1 v1, T2 v2, T3 v3, T4 v4)
                 && !v3.Equals(default(T3))
                 && !v4.Equals(default(T4));
         }
+
+        public static bool Assign<T>(ref T v, T v2)
+            where T : struct
+        {
+            bool result = !v.Equals(v2);
+            v = v2;
+            return result;
+        }
     }
 }

Visual_Studio_2017/GraphicalDebugging/Viewport.cs

@@ -197,23 +197,40 @@ public void DrawPeriodicPoint(LocalCS cs, Geometry.Point point, Geometry.Box box
             PointF p = cs.Convert(point);
             DrawPoint(p);
 
-            double pi2 = 2 * Geometry.HalfAngle(unit);
+            double twoPi = Geometry.FullAngle(unit);
             Pen pen = drawDots ? this.penDot : this.pen;
-            // draw points on the west
-            double x_tmp = point[0] - pi2;
-            while (x_tmp >= box.Min[0])
+
+            // NOTE: Use AssignChanged becasue for big coordinates subtracting/adding
+            //   twoPi doesn't change the value of x_tmp which causes infinite loop
+
+            float x = Math.Min(Math.Max(p.X, 0.0f), cs.Width);
+            double nPeriodsWest = (point[0] - box.Min[0]) / twoPi;
+            float pixelsWest = x;
+            double nPeriodsEast = (box.Max[0] - point[0]) / twoPi;
+            float pixelsEast = cs.Width - x;
+
+            if (nPeriodsWest <= pixelsWest / 5)
             {
-                p.X = cs.ConvertX(x_tmp);
-                DrawPoint(p, pen);
-                x_tmp -= pi2;
+                // draw points on the west
+                double x_tmp = point[0];
+                while (Util.Assign(ref x_tmp, x_tmp - twoPi)
+                    && x_tmp >= box.Min[0])
+                {
+                    p.X = cs.ConvertX(x_tmp);
+                    DrawPoint(p, pen);
+                }
             }
-            // draw points on the east
-            x_tmp = point[0] + pi2;
-            while (x_tmp <= box.Max[0])
+
+            if (nPeriodsEast <= pixelsEast / 5)
             {
-                p.X = cs.ConvertX(x_tmp);
-                DrawPoint(p, pen);
-                x_tmp += pi2;
+                // draw points on the east
+                double x_tmp = point[0];
+                while (Util.Assign(ref x_tmp, x_tmp + twoPi)
+                    && x_tmp <= box.Max[0])
+                {
+                    p.X = cs.ConvertX(x_tmp);
+                    DrawPoint(p, pen);
+                }
             }
         }
 
@@ -359,7 +376,7 @@ private static PointF[] DensifyAndConvert(LocalCS cs, Geometry.Point p0, Geometr
             {
                 double distNorm = Geometry.NormalizedAngleSigned(p1[0] - p0[0], unit);
                 bool intersPole = IsAntipodal(distNorm, unit);
-                double halfPi = Geometry.HalfAngle(unit) / 2;
+                double halfPi = Geometry.RightAngle(unit);
                 double poleLat = p1[1] - p0[1] >= 0 ? halfPi : -halfPi;
                 int intersPoleIndex = -1;
 
@@ -400,7 +417,7 @@ private static PointF[] DensifyAndConvert(LocalCS cs, Geometry.Point p0, Geometr
 
             public static bool IsAntipodal(double distNorm, Geometry.Unit unit)
             {
-                double pi = Geometry.HalfAngle(unit);
+                double pi = Geometry.StraightAngle(unit);
                 return Math.Abs(Math.Abs(distNorm) - pi) < double.Epsilon * pi;
             }
 
@@ -609,8 +626,8 @@ public void DrawPeriodic(LocalCS cs,
                                  IPeriodicDrawable drawer,
                                  bool fill, bool drawDirs, bool drawDots)
         {
-            double pi = Geometry.HalfAngle(unit);
-            float periodf = cs.ConvertDimensionX(2 * pi);
+            double twoPi = Geometry.FullAngle(unit);
+            float periodf = cs.ConvertDimensionX(twoPi);
             float box_minf = cs.ConvertX(box.Min[0]);
             float box_maxf = cs.ConvertX(box.Max[0]);
 
@@ -624,22 +641,24 @@ public void DrawPeriodic(LocalCS cs,
             float minf_i = minf;
             float maxf_i = maxf;
             float translationf = 0;
-            while (maxf_i >= box_minf)
+            while (maxf_i >= box_minf
+                && Util.Assign(ref maxf_i, maxf_i - periodf))
             {
                 translationf -= periodf;
                 minf_i -= periodf;
-                maxf_i -= periodf;
+                //maxf_i -= periodf; // subtracted above
                 if (maxf_i >= box_minf && minf_i <= box_maxf)
                     drawer.DrawOne(this, translationf, fill, drawDirs, drawDots);
             }
             // east
             minf_i = minf;
             maxf_i = maxf;
             translationf = 0;
-            while (minf_i <= box_maxf)
+            while (minf_i <= box_maxf
+                && Util.Assign(ref minf_i, minf_i + periodf))
             {
                 translationf += periodf;
-                minf_i += periodf;
+                //minf_i += periodf; // added above
                 maxf_i += periodf;
                 if (maxf_i >= box_minf && minf_i <= box_maxf)
                     drawer.DrawOne(this, translationf, fill, drawDirs, drawDots);
@@ -694,7 +713,7 @@ public static bool DrawAxes(Graphics graphics, Geometry.Box box, Geometry.Unit u
                 Pen anti_pen = new Pen(colors.AxisColor, 1);
                 anti_pen.DashStyle = DashStyle.Custom;
                 anti_pen.DashPattern = new float[] { 5, 5 };
-                double pi = Geometry.HalfAngle(unit);
+                double pi = Geometry.StraightAngle(unit);
                 double anti_mer = Geometry.NearestAntimeridian(box.Min[0], -1, unit);
                 double prime_mer = anti_mer + pi;
                 double next_anti_mer = anti_mer + 2 * pi;
@@ -706,21 +725,34 @@ public static bool DrawAxes(Graphics graphics, Geometry.Box box, Geometry.Unit u
                 float prime_mer_step = cs.ConvertX(next_prime_mer) - prime_mer_f;
 
                 // Antimeridians
-                for (; anti_mer_f <= w; anti_mer_f += anti_mer_step)
+                while (anti_mer_f <= w
+                    // NOTE: For bug coordinates anti_mer_step may be 0 which results in infinite loop
+                    && Util.Assign(ref anti_mer_f, anti_mer_f + anti_mer_step))
                 {
                     if (anti_mer_f >= 0)
                     {
                         graphics.DrawLine(anti_pen, anti_mer_f, 0, anti_mer_f, h);
                     }
                 }
                 // Prime meridians
-                for (; prime_mer_f <= w; prime_mer_f += prime_mer_step)
+                bool primeMeridiansDrawn = false;
+                while (prime_mer_f <= w
+                    // NOTE: For bug coordinates anti_mer_step may be 0 which results in infinite loop
+                    && Util.Assign(ref prime_mer_f, prime_mer_f += prime_mer_step))
                 {
                     if (prime_mer_f >= 0)
                     {
                         graphics.DrawLine(prime_pen, prime_mer_f, 0, prime_mer_f, h);
+                        primeMeridiansDrawn = true;
                     }
                 }
+                // Prime meridian
+                float p = cs.ConvertX(0.0);
+                if (!primeMeridiansDrawn
+                    && 0 <= p && p <= w)
+                {
+                    graphics.DrawLine(prime_pen, p, 0, p, h);
+                }
                 // Equator
                 float e = cs.ConvertY(0.0);
                 if (0 <= e && e <= h)
@@ -1192,6 +1224,9 @@ public Geometry.Box ViewBox()
                         new Geometry.Point(InverseConvertX(dst_orig_w), InverseConvertY(0)));
         }
 
+        public float Width { get { return dst_orig_w; } }
+        public float Height { get { return dst_orig_h; } }
+
         float dst_orig_w, dst_orig_h;
         float dst_x0, dst_y0;
         double src_x0, src_y0;