diff --git a/src/image.cpp b/src/image.cpp
index 6114dd7..3116bdf 100644
--- a/src/image.cpp
+++ b/src/image.cpp
@@ -2,10 +2,31 @@
 #include <glm/gtc/noise.hpp>
 #include "lodepng.h"
 
-Image::Image(int myDepth, int myWidth, int myHeight, float frequency, float amplitude) :
+std::string getNameFromFilename(const std::string &filename)
+{
+    int end;
+    for(end = filename.size()-1; end > 0; --end)
+    {
+        if(filename[end] == '.')
+            break;
+    }
+    int start;
+    for(start = end; start > 0; --start)
+    {
+        if(filename[start] == '/' || filename[start] == '\\')
+        {
+            ++start;
+            break;
+        }
+    }
+    return filename.substr(start, end-start);
+}
+
+Image::Image(const std::string &name, int myDepth, int myWidth, int myHeight, float frequency, float amplitude) :
     width(myWidth),
     height(myHeight),
-    depth(myDepth)
+    depth(myDepth),
+    m_name(name)
 {
     allocate(width * height * (depth/8));
     unsigned char* data = pixels.data();
@@ -52,6 +73,20 @@ Image::Image(const std::string &pngFile)
     }
 }
 
+Image::Image(const unsigned char *pngPtr, size_t size)
+{
+    unsigned int w, h;
+    unsigned error = lodepng::decode(pixels, w, h, pngPtr, size);
+    if(error)
+        fprintf(stderr, lodepng_error_text(error));
+    else
+    {
+        width = w;
+        height = h;
+        depth = pixels.size()*8/(width*height);
+    }
+}
+
 bool Image::save(const std::string &filename)
 {
     LodePNGColorType colorType;
@@ -62,8 +97,40 @@ bool Image::save(const std::string &filename)
         case 8: colorType = LCT_GREY; break;
         default: return false; break;
     }
-    unsigned error = lodepng::encode(filename, pixels.data(), width, height, colorType, 8);
+    unsigned error = lodepng::encode(filename, pixels, width, height, colorType, 8);
     if(error)
         fprintf(stderr, lodepng_error_text(error));
     return error != 0;
 }
+
+bool Image::save(std::vector<unsigned char> &out)
+{
+    LodePNGColorType colorType;
+    switch(depth)
+    {
+        case 32: colorType = LCT_RGBA; break;
+        case 24: colorType = LCT_RGB; break;
+        case 8: colorType = LCT_GREY; break;
+        default: return false; break;
+    }
+    unsigned error = lodepng::encode(out, pixels, width, height, colorType, 8);
+    if(error)
+        fprintf(stderr, lodepng_error_text(error));
+    return error != 0;
+}
+
+TexturePack::TexturePack(const std::string &filename)
+{
+    m_name = getNameFromFilename(filename);
+    std::FILE *file = std::fopen(filename.c_str(), "r");
+    if(file == NULL)
+        return;
+}
+
+bool TexturePack::save(const std::string &path)
+{
+    std::string filename = path + '/' + m_name + ".tpk";
+    std::FILE *file = std::fopen(filename.c_str(), "w");
+    if(file == NULL)
+        return false;
+}
diff --git a/src/image.h b/src/image.h
index 352ef47..e59da71 100644
--- a/src/image.h
+++ b/src/image.h
@@ -9,17 +9,35 @@ struct Image
     int width;
     int height;
     int depth;
+    std::string m_name;
     std::vector<unsigned char> pixels;
 
     Image() : width(0), height(0), depth(8) {}
 
-    Image(int myDepth, int myWidth, int myHeight, float frequency, float amplitude);
-    
-    Image(const std::string &pngFile);
+    Image(const std::string &name, int myDepth, int myWidth, int myHeight, float frequency, float amplitude);
 
     void allocate(int size)
         { pixels.resize(size); }
     
+    /*
+     * PNG serialization
+     */
+    Image(const std::string &pngFile);
+
+    Image(const unsigned char *pngPtr, size_t size);
+
+    bool save(const std::string &filename);
+
+    bool save(std::vector<unsigned char> &out);
+};
+
+struct TexturePack
+{
+    std::string m_name;
+    std::vector<Image> m_images;
+
+    TexturePack(std::string name) : m_name(name) {}
+    TexturePack(const std::string &filename);
     bool save(const std::string &filename);
 };
 
diff --git a/src/trackballcamera.cpp b/src/trackballcamera.cpp
index 9bf2177..af75d4d 100644
--- a/src/trackballcamera.cpp
+++ b/src/trackballcamera.cpp
@@ -24,10 +24,22 @@ void TrackBallCamera::rotateCamera(float dx, float dy)
 
 void TrackBallCamera::moveCamera(float dx, float dy)
 {
-        glm::mat4 inverseMVP = glm::inverse(m_projection * m_view);
-        glm::vec4 diff = inverseMVP * glm::vec4(dx*m_dist*DEFAULT_MOVE_SPEED, dy*m_dist*DEFAULT_MOVE_SPEED, 0, 1);
-        m_center += glm::vec3(diff);
-        computeView();
+    // this is absolutely not efficient, but it works
+    // you can try to optimize it, but please don't break it
+    glm::vec4 screenPos(m_center, 1);
+    glm::mat4 MVP = m_projection * m_view;
+    glm::mat4 inverseMVP = glm::inverse(MVP);
+    screenPos = MVP * screenPos;
+    glm::vec4 pos(dx, -dy, (m_dist/m_far)*2 - 1, 1);
+    pos *= screenPos.w;
+    glm::vec4 diff = (inverseMVP * glm::vec4(0, 0, pos.z, pos.w)) - (inverseMVP * pos);
+    moveCamera(glm::vec3(diff));
+}
+
+void TrackBallCamera::moveCamera(const glm::vec3 &diff)
+{
+    m_center += diff;
+    computeView();
 }
 
 void TrackBallCamera::reset()
diff --git a/src/trackballcamera.h b/src/trackballcamera.h
index e4e0d5a..17cc7c5 100644
--- a/src/trackballcamera.h
+++ b/src/trackballcamera.h
@@ -20,6 +20,7 @@ public:
 
     void rotateCamera(float dx, float dy);
     void moveCamera(float dx, float dy);
+    void moveCamera(const glm::vec3 &diff);
 	void zoom(int nbScrolls);
     void reset();
     glm::vec3 getDefaultPxInfo();