From 63cf40eeca21876bdc18a58cc82e010894f4a446 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 27 Apr 2018 16:33:18 +1000
Subject: [PATCH] poisson-tool: use function objects for distances

---
 geom/sample.hpp   |  8 ++++----
 tools/poisson.cpp | 12 +++++++++---
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/geom/sample.hpp b/geom/sample.hpp
index f313032d..f88fb1b5 100644
--- a/geom/sample.hpp
+++ b/geom/sample.hpp
@@ -94,11 +94,11 @@ namespace util::geom {
         /// furthest from all selected points.
         ///
         /// \return a vector of the computed points
-        template <typename SamplerT, typename GeneratorT>
+        template <typename SamplerT, typename DistanceT, typename GeneratorT>
         auto
         poisson (SamplerT const &target,
                  GeneratorT &&gen,
-                 float minimum_distance,
+                 DistanceT &&minimum_distance,
                  size_t candidates_count)
 
         {
@@ -138,7 +138,7 @@ namespace util::geom {
                         d = util::min (d, distance (p, q));
 
                     // record if it's the furthest away
-                    if (d > best_distance) {
+                    if (d > best_distance && d > minimum_distance (p)) {
                         best_distance = d;
                         best_index = i;
                     }
@@ -146,7 +146,7 @@ namespace util::geom {
 
                 // if we didn't find a suitable point then we give up and
                 // return the points we found, otherwise record the best point
-                if (best_distance < minimum_distance)
+                if (best_distance <= 0)
                     break;
 
                 selected.push_back (candidates[best_index]);
diff --git a/tools/poisson.cpp b/tools/poisson.cpp
index 35c44899..b858044a 100644
--- a/tools/poisson.cpp
+++ b/tools/poisson.cpp
@@ -1,6 +1,7 @@
 #include "cmdopt.hpp"
-#include "geom/sample.hpp"
+#include "functor.hpp"
 #include "geom/aabb.hpp"
+#include "geom/sample.hpp"
 
 #include <cstdlib>
 #include <iostream>
@@ -30,6 +31,12 @@ private:
 
 
 ///////////////////////////////////////////////////////////////////////////////
+struct height {
+    float
+    operator() (util::point2f p) const { return std::pow (p.y / 100, 3.f); }
+};
+
+
 int
 main (int argc, char **argv)
 {
@@ -45,11 +52,10 @@ main (int argc, char **argv)
 
     opts.scan (argc, argv);
 
-
     std::cout << "<svg height='" << area.h << "' width='" << area.h << "'>";
     for (auto p: util::geom::surface::poisson (util::geom::surface::sampler (area),
                                                std::default_random_engine (),
-                                               distance,
+                                               util::functor::constant (distance),
                                                samples))
     {
         std::cout << "<circle cx='" << p.x << "' cy='" << p.y << "' r='1' />";