izzi-points.h

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// izzi 2d points  -*- mode: C++ -*-
 
// Copyright (c) 2025, Benjamin De Kosnik <b.dekosnik@gmail.com>
 
// This file is part of the alpha60 library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
 
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
 
#ifndef izzi_POINTS_H
#define izzi_POINTS_H 1
 
namespace svg {
 
/// Point (x,y) in 2D space, space_type defaults to double.
using point_2t = std::tuple<space_type, space_type>;
 
/// Point (x,y) in 2D space with weight n.
using point_2tn = std::tuple<ulong, point_2t>;
 
/// Named Point (x,y) in 2D space.
using point_2ts = std::tuple<string, point_2t>;
 
/// Convert point_2t to string.
string
to_string(point_2t p)
{
  auto [ x, y ] = p;
  std::ostringstream oss;
  oss << x << ',' << y;
  return oss.str();
}
 
/// Split range, so one dimension of (x,y) cartesian plane.
using vspace = std::vector<space_type>;
 
/// Latitude and Longitude Ranges.
using srange = std::set<point_2t>;
using srangen = std::set<point_2tn>;
using vrange = std::vector<point_2t>;
using vrangen = std::vector<point_2tn>;
using vvranges = std::vector<vrange>;
 
using vrangenamed = std::vector<point_2ts>;
 
 
/// Decompose/split 2D ranges to 1D spaces, perhaps with scaling.
void
split_vrange(const vrange& cpoints, vspace& xpoints, vspace& ypoints,
         const double xscale = 1, const double yscale = 1)
{
 for (const auto& [x, y] : cpoints)
   {
     xpoints.push_back(x / xscale);
     ypoints.push_back(y / yscale);
   }
}
 
 
/// Union two ranges.
vrange
union_vrange(const vrange& r1, const vrange& r2)
{
  vrange vr;
  vr.insert(vr.end(), r1.begin(), r1.end());
  vr.insert(vr.end(), r2.begin(), r2.end());
  return vr;
}
 
 
/// For each dimension of vrnage, find min/max and return (xmax, ymax)
/// NB: Assumes zero is min.
point_2t
max_vrange(vspace& xpoints, vspace& ypoints, const uint pown)
{
  point_2t rangemaxx = { 0, 0 };
  if (!xpoints.empty() && !ypoints.empty())
    {
      sort(xpoints.begin(), xpoints.end());
      sort(ypoints.begin(), ypoints.end());
 
      // For x axis, need to insert padding iff axes are scaled down
      // and/or have values with truncated significant digits.
      const bool padp(true);
      if (padp)
    {
      const double sigd = pow(10, pown);
 
      const double dx = xpoints.back();
      double ix = std::round(dx * sigd) / sigd;
      if (ix > dx)
        xpoints.push_back(ix);
 
      const double dy = ypoints.back();
      uint iy = std::round(dy * sigd) / sigd;
      if (iy > dy)
        ypoints.push_back(iy);
    }
 
      // Find combined ranges, assume zero start.
      rangemaxx = std::make_tuple(xpoints.back(), ypoints.back());
    }
  return rangemaxx;
}
 
 
/// Just the range info, none of the temporary objects.
point_2t
max_vrange(const vrange& points, const uint pown,
       const double xscale = 1, const double yscale = 1)
{
  vspace pointsx;
  vspace pointsy;
  split_vrange(points, pointsx, pointsy, xscale, yscale);
  point_2t ret = max_vrange(pointsx, pointsy, pown);
  return ret;
}
 
 
/// Truncate double to double with pown signifigant digits.
vspace
narrow_vspace(const vspace& points, uint pown)
{
  const double sigd = pow(10, pown);
  vspace npoints;
  for (const double& d : points)
    {
      double dn(d);
      if (dn > 0)
    {
      uint itrunc(dn * sigd);
      npoints.push_back(itrunc / sigd);
    }
      else
    npoints.push_back(dn);
    }
  return npoints;
}
 
/// Find cartesian distance between two 2D points.
space_type
distance_cartesian(const point_2t& p1, const point_2t& p2)
{
  auto [ x1, y1 ] = p1;
  auto [ x2, y2 ] = p2;
  auto distancex = (x2 - x1) * (x2 - x1);
  auto distancey = (y2 - y1) * (y2 - y1);
  space_type distance = sqrt(distancex + distancey);
  return distance;
}
 
 
// Does point p1 of radius r1 intersect point p2 with radius r2?
// https://developer.mozilla.org x 2D_collision_detection
bool
detect_collision(const point_2t& p1, const int r1,
         const point_2t& p2, const int r2)
{
  bool ret(false);
  if (distance_cartesian(p1, p2) < r1 + r2)
    ret = true;
  return ret;
}
 
} // namespace svg
 
struct Point
{
  double    x, y;
  std::string   name;
 
  Point(double x = 0, double y = 0, const std::string s = "")
  : x(x), y(y), name(s) { }
 
  double
  distance(const Point& other) const
  { return std::hypot(x - other.x, y - other.y); }
 
  bool
  operator==(const Point& other) const
  { return x == other.x && y == other.y; }
 
  Point
  operator+(const Point& other) const
  { return Point(x + other.x, y + other.y); }
 
  Point
  operator/(double scalar) const
  { return Point(x / scalar, y / scalar); }
};
 
struct WeightedPoint
{
  Point        pt;
  size_t    weight;
 
  WeightedPoint(const Point& p, size_t w)
  : pt(p.x, p.y, p.name), weight(w) { }
};
 
using vpoints = std::vector<Point>;
using vwpoints = std::vector<WeightedPoint>;
 
 
namespace svg {
 
/// Convert point_2ts to Point.
vpoints
vrangenamed_to_points(const vrangenamed& inpoints)
{
  vpoints outpoints;
  outpoints.reserve(inpoints.size());
 
  auto lconv = [](const point_2ts& p)
  { auto [ s, pt ] = p; auto [x, y] = pt; return Point(x, y, s); };
  std::ranges::transform(inpoints, std::back_inserter(outpoints), lconv);
  return outpoints;
}
 
/// Convert Point to point_2t
vrangenamed
points_to_vrangenamed(const vpoints& inpoints)
{
  using std::make_tuple;
  vrangenamed outpoints;
  outpoints.reserve(inpoints.size());
 
  auto lconv = [](const Point& p){auto pt = make_tuple(p.x, p.y); return make_tuple(p.name, pt); };
  std::ranges::transform(inpoints, std::back_inserter(outpoints), lconv);
  return outpoints;
}
 
} // namespace svg
 
#endif