From 7b374c70aed461737d9831c1f271a58f0de1fcb7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Tue, 13 Feb 2018 18:42:15 +0100
Subject: [PATCH] Surfaces now provide a location hint

This is supposed to be a point in space close to the surface
---
 Implicit.hpp                 | 2 ++
 PerlinNoise.cpp              | 8 ++++++++
 PerlinNoise.hpp              | 3 +++
 spheroid.cpp                 | 4 ++++
 spheroid.hpp                 | 2 ++
 tests/TestImplicitSphere.cpp | 4 ++++
 tests/TestImplicitSphere.hpp | 2 ++
 7 files changed, 25 insertions(+)

diff --git a/Implicit.hpp b/Implicit.hpp
index dc4a3d5..721f963 100644
--- a/Implicit.hpp
+++ b/Implicit.hpp
@@ -8,6 +8,8 @@ class ImplicitSurface {
         double operator()(const Point& pt) const;
         Point getCenter() const { return center;}
 
+        virtual Point location_hint() const = 0;
+
         /// Compute the normal vector to the isosurface at `pt`
         Point normal_at(const Point& pt) const;
     protected:
diff --git a/PerlinNoise.cpp b/PerlinNoise.cpp
index af46b57..7857b35 100644
--- a/PerlinNoise.cpp
+++ b/PerlinNoise.cpp
@@ -121,3 +121,11 @@ Point PerlinNoise::normal_vector(double x, double y) {
     );
     return product;
 }
+
+Point PerlinNoise::location_hint() const {
+    return location_hint(0, 0);
+}
+
+Point PerlinNoise::location_hint(double x, double z) const {
+    return Point(x, noise(x, z), z);
+}
diff --git a/PerlinNoise.hpp b/PerlinNoise.hpp
index e013e9e..a03760b 100644
--- a/PerlinNoise.hpp
+++ b/PerlinNoise.hpp
@@ -15,6 +15,9 @@ class PerlinNoise : public ImplicitSurface {
         double operator() (double _x, double _y, double _z) const;
         double noise(double x, double y) const;
         Point normal_vector(double x, double y);
+
+        virtual Point location_hint() const;
+        Point location_hint(double x, double z) const;
     private:
         double noise(double x, double y, double z) const;
         double fade(double t) const;
diff --git a/spheroid.cpp b/spheroid.cpp
index 88dbb76..7d347fb 100644
--- a/spheroid.cpp
+++ b/spheroid.cpp
@@ -75,3 +75,7 @@ double Spheroid::operator() (double _x, double _y, double _z) const {
                   + pow(_y, 2) / pow(p, 2)
                   + pow(_z, 2) / pow(q, 2) -1);
 }
+
+Point Spheroid::location_hint() const {
+    return Point(0, p, 0);
+}
diff --git a/spheroid.hpp b/spheroid.hpp
index 1e6f0f0..52c0499 100644
--- a/spheroid.hpp
+++ b/spheroid.hpp
@@ -23,6 +23,8 @@ class Spheroid : public ImplicitSurface {
         void check_perlin_collision(PerlinNoise perlin);
         Point getNormalVector() const { return normal_vector;}
         double operator() (double _x, double _y, double _z) const;
+
+        virtual Point location_hint() const;
     private:
         /**
          * p corresponds to the half-height of the ball,
diff --git a/tests/TestImplicitSphere.cpp b/tests/TestImplicitSphere.cpp
index 575dc56..afb5fdc 100644
--- a/tests/TestImplicitSphere.cpp
+++ b/tests/TestImplicitSphere.cpp
@@ -7,3 +7,7 @@ double TestImplicitSphere::operator()(double x, double y, double z) const {
             + sq(center.z - z))
         + sq(radius);
 }
+
+Point TestImplicitSphere::location_hint() const {
+    return Point(center.x + radius, center.y, center.z);
+}
diff --git a/tests/TestImplicitSphere.hpp b/tests/TestImplicitSphere.hpp
index ab0d13f..4171bce 100644
--- a/tests/TestImplicitSphere.hpp
+++ b/tests/TestImplicitSphere.hpp
@@ -8,6 +8,8 @@ class TestImplicitSphere: public ImplicitSurface {
             ImplicitSurface(center), radius(r) {}
         virtual double operator()(double x, double y, double z) const;
 
+        virtual Point location_hint() const;
+
     private:
         double radius;
 };