Initial commit.

room_force.h

@@ -0,0 +1,45 @@
+// -*- C++ -*-
+
+#ifndef MBOSTOCK_ROOM_FORCE_H
+#define MBOSTOCK_ROOM_FORCE_H
+
+#include "physics/force.h"
+#include "physics/shape.h"
+#include "physics/vector.h"
+
+namespace mbostock {
+
+  class Particle;
+  class Shape;
+
+  /**
+   * Defines a force that applies to the player when the player intersects a
+   * given shape. For example, this can be used to represent a fan blowing on
+   * the player, which the force of the fan stronger near the fan blades,
+   * falling off to zero outside of the fan's stream.
+   */
+  class RoomForce : public UnaryForce {
+  public:
+    virtual const Shape& shape() const = 0;
+  };
+
+  /**
+   * A simple room force that applies a constant force within an axis-aligned
+   * box. More elaborate forces can be approximated by composing multiple (even
+   * overlapping) constant room forces.
+   */
+  class ConstantRoomForce : public RoomForce {
+  public:
+    ConstantRoomForce(const Vector& min, const Vector& max, const Vector& f);
+
+    virtual const Shape& shape() const;
+    virtual Vector force(const Particle& p);
+
+  private:
+    AxisAlignedBox box_;
+    Vector force_;
+  };
+
+}
+
+#endif