Add some structure for the ground.

FlatGround.cpp

@@ -0,0 +1,6 @@
+#include "FlatGround.hpp"
+
+
+double FlatGround::operator() (double, double) const {
+    return 0. ;
+}

FlatGround.hpp

@@ -0,0 +1,6 @@
+#pragma once
+#include "Ground.hpp"
+
+class FlatGround : public Ground {
+    double operator() (double, double) const;
+};

Ground.hpp

@@ -0,0 +1,8 @@
+#pragma once
+
+#include "common_structures.hpp"
+
+class Ground {
+    public:
+        virtual double operator() (double, double) const = 0;
+};

Makefile

@@ -11,6 +11,9 @@ OBJS=Implicit.o \
 	 Mesh.o \
 	 spheroid.o \
 	 Ball.o \
+	 Ground.o \
+	 FlatGround.o \
+	 PerlinGround.o \
 	 PerlinNoise.o \
 	 util/ObjParser.o \
 	 MarchingCubes.o \

PerlinGround.cpp

@@ -0,0 +1,9 @@
+#include "PerlinGround.hpp"
+
+PerlinGround::PerlinGround() : surface(PerlinNoise()) {}
+PerlinGround::PerlinGround(unsigned int seed) : surface(PerlinNoise(seed)) {}
+
+double PerlinGround::operator() (double x, double z) const {
+    return surface.noise(x, z);
+}
+

PerlinGround.hpp

@@ -0,0 +1,12 @@
+#pragma once
+#include "Ground.hpp"
+#include "PerlinNoise.hpp"
+
+class PerlinGround : public Ground {
+    public:
+        PerlinGround();
+        PerlinGround(unsigned int seed);
+        double operator() (double, double) const;
+    private:
+        PerlinNoise surface;
+};