From 798a3d66fc6111daf0fb5f90de25471145f55cfa Mon Sep 17 00:00:00 2001
From: Pierre Abbat <phma@bezitopo.org>
Date: Sun, 9 Sep 2018 22:51:20 +0000
Subject: [PATCH] Add functions to format curvature and clothance (untested)

These need to be outside the Measure class because, when using feet,
curvature and clothance are expressed as angle, a different quantity.
Also add curvature and clothance to measure.{h,cpp}.
---
 arc.cpp     |  33 ++++++++++++++++
 arc.h       |   4 +-
 measure.cpp | 112 ++++++++++++++++++++++++++++------------------------
 measure.h   |   6 +++
 spiral.cpp  |  30 ++++++++++++++
 spiral.h    |   2 +
 6 files changed, 134 insertions(+), 53 deletions(-)

diff --git a/arc.cpp b/arc.cpp
index ea7a49e7..ea15306d 100644
--- a/arc.cpp
+++ b/arc.cpp
@@ -26,6 +26,8 @@
 #include "vcurve.h"
 #include "spiral.h"
 
+using namespace std;
+
 arc::arc()
 {
   start=end=xyz(0,0,0);
@@ -197,3 +199,34 @@ double arc::in(xy pnt)
    interpolation and calong(). Then use parabolic interpolation to find
    the closest point on the circle.
    */
+
+string formatCurvature(double curvature,Measure ms)
+/* The coherent unit of curvature is the diopter (not an SI unit, but coherent
+ * with SI). For roads, the millidiopter is closer to the size. When roads
+ * are measured in feet, however, curvature is expressed not in per feet,
+ * but by stating the angle subtended by a 100-foot arc. Railroads use
+ * a 100-foot chord, which I may add later (it'll require a flag somewhere).
+ */
+{
+  double hundredFeet=ms.parseMeasurement("100 ft",LENGTH).magnitude;
+  bool isFoot;
+  string hundredFeetString=ms.formatMeasurement(hundredFeet,LENGTH);
+  int i;
+  for (i=0;i<hundredFeetString.length();i++)
+  {
+    if (hundredFeetString[i]=='1')
+    {
+      isFoot=true;
+      break;
+    }
+    if (hundredFeetString[i]=='3')
+    {
+      isFoot=false;
+      break;
+    }
+  }
+  if (isFoot)
+    return ms.formatMeasurementUnit(curvature*hundredFeet,ANGLE);
+  else
+    return ms.formatMeasurementUnit(curvature,CURVATURE);
+}
diff --git a/arc.h b/arc.h
index 464e9530..b726aca1 100644
--- a/arc.h
+++ b/arc.h
@@ -74,6 +74,8 @@ class arc: public segment
   virtual bool isTooCurly();
   void split(double along,arc &a,arc &b);
   //xyz midpoint();
-  };
+};
+
+std::string formatCurvature(double curvature,Measure ms);
 
 #endif
diff --git a/measure.cpp b/measure.cpp
index b2d66cb2..44eaf95a 100644
--- a/measure.cpp
+++ b/measure.cpp
@@ -51,32 +51,36 @@ struct cf
 
 cf cfactors[]=
 {
-  FOOT,		0.3048,			// ft (any of three)
-  CHAIN,	20.1168,		// ch (any of three)
-  MILE,		1609.344,		// mi (any of three)
-  0,		1,			// unknown unit
-  MILLIMETER,	0.001,			// mm
-  MICROMETER,	0.000001,		// μm
-  KILOMETER,	1000,			// km
-  METER,	1,			// m
-  SQUAREMETER,	1,			// m²
-  SQUAREFOOT,	0.09290304,		// ft²
-  HECTARE,	10000,			// ha
-  ACRE,		4046.8564224,		// ac
-  GRAM,		0.001,			// g
-  KILOGRAM,	1.0,			// kg
-  POUND,	0.45359237,		// lb
-  HOUR,		3600,			// hour
-  RADIAN,	1,
-  DEGREE,	M_PI/180,
-  GON,		M_PI/200,
-  ARCMINUTE,	M_PI/10800,
-  ARCSECOND,	M_PI/648000,
-  RADIAN_B,	1073741824./M_PI,
-  DEGREE_B,	1073741824./180,
-  GON_B,	1073741824./200,
-  ARCMINUTE_B,	1073741824./10800,
-  ARCSECOND_B,	1073741824./648000,
+  FOOT,			0.3048,			// ft (any of three)
+  CHAIN,		20.1168,		// ch (any of three)
+  MILE,			1609.344,		// mi (any of three)
+  0,			1,			// unknown unit
+  MILLIMETER,		0.001,			// mm
+  MICROMETER,		0.000001,		// μm
+  KILOMETER,		1000,			// km
+  METER,		1,			// m
+  SQUAREMETER,		1,			// m²
+  SQUAREFOOT,		0.09290304,		// ft²
+  HECTARE,		10000,			// ha
+  ACRE,			4046.8564224,		// ac
+  GRAM,			0.001,			// g
+  KILOGRAM,		1.0,			// kg
+  POUND,		0.45359237,		// lb
+  DIOPTER,		1,
+  MILLIDIOPTER,		0.001,
+  SQUAREDIOPTER,	1,
+  SQUAREMILLIDIOPTER,	1e-6,
+  HOUR,			3600,			// hour
+  RADIAN,		1,
+  DEGREE,		M_PI/180,
+  GON,			M_PI/200,
+  ARCMINUTE,		M_PI/10800,
+  ARCSECOND,		M_PI/648000,
+  RADIAN_B,		1073741824./M_PI,
+  DEGREE_B,		1073741824./180,
+  GON_B,		1073741824./200,
+  ARCMINUTE_B,		1073741824./10800,
+  ARCSECOND_B,		1073741824./648000,
 };
 #define nunits (sizeof(cfactors)/sizeof(struct cf))
 struct symbol
@@ -88,32 +92,36 @@ struct symbol
 symbol symbols[]=
 /* The first symbol is the canonical one, if there is one. */
 {
-  MILLIMETER,	"mm",
-  MICROMETER,	"µm", //0000b5 00006d
-  MICROMETER,	"μm", //0003bc 00006d
-  MICROMETER,	"um",
-  KILOMETER,	"km",
-  MILE,		"mi",
-  FOOT,		"ft",
-  FOOT,		"'",
-  METER,	"m",
-  SQUAREMETER,	"m²",
-  SQUAREFOOT,	"ft²",
-  HECTARE,	"ha",
-  ACRE,		"ac",
-  GRAM,		"g",
-  KILOGRAM,	"kg",
-  POUND,	"lb",
-  RADIAN,	"rad",
-  DEGREE,	"°",
-  GON,		"gon",
-  ARCMINUTE,	"′",
-  ARCSECOND,	"″",
-  RADIAN_B,	"rad",
-  DEGREE_B,	"°",
-  GON_B,	"gon",
-  ARCMINUTE_B,	"′",
-  ARCSECOND_B,	"″",
+  MILLIMETER,		"mm",
+  MICROMETER,		"µm", //0000b5 00006d
+  MICROMETER,		"μm", //0003bc 00006d
+  MICROMETER,		"um",
+  KILOMETER,		"km",
+  MILE,			"mi",
+  FOOT,			"ft",
+  FOOT,			"'",
+  METER,		"m",
+  SQUAREMETER,		"m²",
+  SQUAREFOOT,		"ft²",
+  HECTARE,		"ha",
+  ACRE,			"ac",
+  GRAM,			"g",
+  KILOGRAM,		"kg",
+  POUND,		"lb",
+  DIOPTER,		"dpt",
+  MILLIDIOPTER,		"mdpt",
+  SQUAREDIOPTER,	"dpt²",
+  SQUAREMILLIDIOPTER,	"mdpt²",
+  RADIAN,		"rad",
+  DEGREE,		"°",
+  GON,			"gon",
+  ARCMINUTE,		"′",
+  ARCSECOND,		"″",
+  RADIAN_B,		"rad",
+  DEGREE_B,		"°",
+  GON_B,		"gon",
+  ARCMINUTE_B,		"′",
+  ARCSECOND_B,		"″",
 };
 #define nsymbols (sizeof(symbols)/sizeof(struct symbol))
 
diff --git a/measure.h b/measure.h
index 3bb6aa9e..9a916a3c 100644
--- a/measure.h
+++ b/measure.h
@@ -67,6 +67,10 @@
 #define ARCSECOND_B 0x003801400000
 #define GON_B 0x003800c00000
 #define RADIAN_B 0x003800400000
+#define DIOPTER 0x002b00400000
+#define SQUAREDIOPTER 0x003900400000
+#define MILLIDIOPTER 0x002b003b0000
+#define SQUAREMILLIDIOPTER 0x0039003b0000
 /* These are physical quantity codes.
  * ANGLE is used when the angle is in radians (latitude and longitude, except
  * in geolattices); ANGLE_B is used when it's in fixed-point binary (bearings,
@@ -80,6 +84,8 @@
 #define VOLUME 0x002800000000
 #define ANGLE 0x002000000000
 #define ANGLE_B 0x003800000000
+#define CURVATURE 0x002b00000000
+#define CLOTHANCE 0x003900000000
 /* These are precision codes. DEC3 = 3 digits after the decimal point.
  * FIXLARGER means that it's in fixed point with larger units, e.g.
  * ARCSECOND+FIXLARGER+DEC3 means degrees, minutes, and seconds with
diff --git a/spiral.cpp b/spiral.cpp
index 0f22f950..acceb75f 100644
--- a/spiral.cpp
+++ b/spiral.cpp
@@ -522,3 +522,33 @@ void spiralarc::setcurvature(double startc,double endc)
   if (abs(midbear-lastmidbear)>1 || dist(mid,lastmid)>1e-6)
     cur=clo=len=NAN;
 }
+
+string formatClothance(double clothance,Measure ms)
+/* The coherent unit of clothance is the square diopter (not an SI unit, but
+ * coherent with SI). For roads, the square millidiopter is closer to the size.
+ * When roads are measured in feet, however, clothance is expressed not in per
+ * square feet, but by stating the change in degree of curve over a 100-foot arc.
+ */
+{
+  double hundredFeet=ms.parseMeasurement("100 ft",LENGTH).magnitude;
+  bool isFoot;
+  string hundredFeetString=ms.formatMeasurement(hundredFeet,LENGTH);
+  int i;
+  for (i=0;i<hundredFeetString.length();i++)
+  {
+    if (hundredFeetString[i]=='1')
+    {
+      isFoot=true;
+      break;
+    }
+    if (hundredFeetString[i]=='3')
+    {
+      isFoot=false;
+      break;
+    }
+  }
+  if (isFoot)
+    return ms.formatMeasurementUnit(clothance*hundredFeet*hundredFeet,ANGLE);
+  else
+    return ms.formatMeasurementUnit(clothance,CLOTHANCE);
+}
diff --git a/spiral.h b/spiral.h
index 80791634..b0c7219a 100644
--- a/spiral.h
+++ b/spiral.h
@@ -124,4 +124,6 @@ class spiralarc: public segment
   }
 };
 
+std::string formatClothance(double clothance,Measure ms);
+
 #endif