diff --git a/demos/opengl/camera.h b/demos/opengl/camera.h
new file mode 100644
index 0000000..15714d2
--- /dev/null
+++ b/demos/opengl/camera.h
@@ -0,0 +1,118 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef EIGEN_CAMERA_H
+#define EIGEN_CAMERA_H
+
+#include <Eigen/Geometry>
+#include <QObject>
+// #include <frame.h>
+
+class Frame
+{
+  public:
+    EIGEN_MAKE_ALIGNED_OPERATOR_NEW
+    
+    inline Frame(const Eigen::Vector3f& pos = Eigen::Vector3f::Zero(),
+                 const Eigen::Quaternionf& o = Eigen::Quaternionf())
+      : orientation(o), position(pos)
+    {}
+    Frame lerp(float alpha, const Frame& other) const
+    {
+      return Frame((1.f-alpha)*position + alpha * other.position,
+                   orientation.slerp(alpha,other.orientation));
+    }
+
+    Eigen::Quaternionf orientation;
+    Eigen::Vector3f position;
+};
+
+class Camera
+{
+  public:
+    EIGEN_MAKE_ALIGNED_OPERATOR_NEW
+
+    Camera(void);
+    
+    Camera(const Camera& other);
+    
+    virtual ~Camera();
+    
+    Camera& operator=(const Camera& other);
+    
+    void setViewport(uint offsetx, uint offsety, uint width, uint height);
+    void setViewport(uint width, uint height);
+    
+    inline uint vpX(void) const { return mVpX; }
+    inline uint vpY(void) const { return mVpY; }
+    inline uint vpWidth(void) const { return mVpWidth; }
+    inline uint vpHeight(void) const { return mVpHeight; }
+
+    inline float fovY(void) const { return mFovY; }
+    void setFovY(float value);
+    
+    void setPosition(const Eigen::Vector3f& pos);
+    inline const Eigen::Vector3f& position(void) const { return mFrame.position; }
+
+    void setOrientation(const Eigen::Quaternionf& q);
+    inline const Eigen::Quaternionf& orientation(void) const { return mFrame.orientation; }
+
+    void setFrame(const Frame& f);
+    const Frame& frame(void) const { return mFrame; }
+    
+    void setDirection(const Eigen::Vector3f& newDirection);
+    Eigen::Vector3f direction(void) const;
+    void setUp(const Eigen::Vector3f& vectorUp);
+    Eigen::Vector3f up(void) const;
+    Eigen::Vector3f right(void) const;
+    
+    void setTarget(const Eigen::Vector3f& target);
+    inline const Eigen::Vector3f& target(void) { return mTarget; }
+    
+    const Eigen::Affine3f& viewMatrix(void) const;
+    const Eigen::Matrix4f& projectionMatrix(void) const;
+    
+    void rotateAroundTarget(const Eigen::Quaternionf& q);
+    void localRotate(const Eigen::Quaternionf& q);
+    void zoom(float d);
+    
+    void localTranslate(const Eigen::Vector3f& t);
+    
+    /** Setup OpenGL matrices and viewport */
+    void activateGL(void);
+    
+    Eigen::Vector3f unProject(const Eigen::Vector2f& uv, float depth, const Eigen::Matrix4f& invModelview) const;
+    Eigen::Vector3f unProject(const Eigen::Vector2f& uv, float depth) const;
+    
+  protected:
+    void updateViewMatrix(void) const;
+    void updateProjectionMatrix(void) const;
+
+  protected:
+
+    uint mVpX, mVpY;
+    uint mVpWidth, mVpHeight;
+
+    Frame mFrame;
+    
+    mutable Eigen::Affine3f mViewMatrix;
+    mutable Eigen::Matrix4f mProjectionMatrix;
+
+    mutable bool mViewIsUptodate;
+    mutable bool mProjIsUptodate;
+
+    // used by rotateAroundTarget
+    Eigen::Vector3f mTarget;
+    
+    float mFovY;
+    float mNearDist;
+    float mFarDist;
+};
+
+#endif // EIGEN_CAMERA_H