Move source to src.

src/physics/force.h

@@ -0,0 +1,105 @@
+// -*- C++ -*-
+
+#ifndef MBOSTOCK_FORCE_H
+#define MBOSTOCK_FORCE_H
+
+#include "vector.h"
+
+namespace mbostock {
+
+  class Particle;
+
+  class UnaryForce {
+  public:
+    virtual ~UnaryForce() {}
+
+    void apply(Particle& p);
+
+    virtual Vector force(const Particle& p)  = 0;
+  };
+
+  class BinaryForce {
+  public:
+    virtual ~BinaryForce() {}
+
+    void apply(Particle& a, Particle& b);
+
+    virtual Vector force(const Particle& a, const Particle& b) = 0;
+  };
+
+  class RandomForce : public UnaryForce {
+  public:
+    RandomForce(float k);
+
+    virtual Vector force(Particle& p);
+
+  private:
+    float k_;
+  };
+
+  class GravitationalForce : public UnaryForce {
+  public:
+    GravitationalForce(float g);
+
+    virtual Vector force(const Particle& p);
+
+  private:
+    float g_;
+  };
+
+  class LinearDragForce : public UnaryForce {
+  public:
+    LinearDragForce(float kd);
+
+    virtual Vector force(const Particle& p);
+
+  private:
+    float kd_;
+  };
+
+  class QuadraticDragForce : public UnaryForce {
+  public:
+    QuadraticDragForce(float kd);
+
+    virtual Vector force(const Particle& p);
+
+  private:
+    float kd_;
+  };
+
+  class HookeForce : public BinaryForce {
+  public:
+    HookeForce(float r, float ks);
+
+    virtual Vector force(const Particle& a, const Particle& b);
+
+  private:
+    float r_;
+    float ks_;
+  };
+
+  class DampenedHookeForce : public BinaryForce {
+  public:
+    DampenedHookeForce(float r, float ks, float kd);
+
+    virtual Vector force(const Particle& a, const Particle& b);
+
+  private:
+    float r_;
+    float ks_;
+    float kd_;
+  };
+
+  class CoulombForce : public BinaryForce {
+  public:
+    CoulombForce(float e);
+
+    virtual Vector force(const Particle& a, const Particle& b);
+
+  private:
+    float e_;
+  };
+
+}
+
+#endif