diff --git a/TODO b/TODO
index 60b2312..1a0682c 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,5 @@
 - Implement scaling and scrolling on previews.
+- Replace FILE* by a custom type for Save and Load.
 - Water and terrain LOD moves with the camera, fix it like in the wanderer.
 - Restore render progress.
 - Find a licence and apply it.
-- Translate UI ?
diff --git a/gui_qt/baseform.h b/gui_qt/baseform.h
index 877e4f4..8a476a6 100644
--- a/gui_qt/baseform.h
+++ b/gui_qt/baseform.h
@@ -8,6 +8,7 @@
 #include "baseinput.h"
 #include "../lib_paysages/shared/types.h"
 #include "../lib_paysages/noise.h"
+#include "../lib_paysages/color.h"
 
 class BaseForm:public QWidget
 {
diff --git a/gui_qt/dialogcolorgradation.cpp b/gui_qt/dialogcolorgradation.cpp
index 624b5d0..8b2fd00 100644
--- a/gui_qt/dialogcolorgradation.cpp
+++ b/gui_qt/dialogcolorgradation.cpp
@@ -10,117 +10,20 @@
 #include <QPushButton>
 #include "baseform.h"
 #include "tools.h"
-
-/**************** Preview ****************/
-class PreviewColorGradation:public BasePreview
-{
-public:
-    PreviewColorGradation(QWidget* parent, ColorGradation* gradation): BasePreview(parent)
-    {
-        _gradation_original = gradation;
-        _gradation_preview = *gradation;
-        setMinimumSize(300, 30);
-        setMaximumSize(300, 30);
-        resize(300, 30);
-        // TODO No scrolling/scaling
-    }
-
-protected:
-    void updateData()
-    {
-        _gradation_preview = *_gradation_original;
-    }
-    QColor getColor(double x, double y)
-    {
-        return colorToQColor(colorGradationGet(&_gradation_preview, x / 600 + 0.5));
-    }
-private:
-    ColorGradation* _gradation_original;
-    ColorGradation _gradation_preview;
-};
-
-/**************** Form ****************/
-class FormColorGradation:public BaseForm
-{
-public:
-    FormColorGradation(QWidget* parent, ColorGradation* gradation):BaseForm(parent, true, true)
-    {
-        QPushButton* button;
-        _gradation = gradation;
-        
-        addPreview(new PreviewColorGradation(this, _gradation), tr("Preview"));
-        
-        addInputDouble(tr("Position"), &_layer.start, 0.0, 1.0, 0.01, 0.1);
-        addInputColor(tr("Color"), &_layer.col);
-        
-        button = addButton(tr("Validate"));
-        QObject::connect(button, SIGNAL(clicked()), parent, SLOT(accept()));
-        
-        button = addButton(tr("Revert"));
-        QObject::connect(button, SIGNAL(clicked()), parent, SLOT(revert()));
-        
-        button = addButton(tr("Cancel"));
-        QObject::connect(button, SIGNAL(clicked()), parent, SLOT(reject()));
-        
-        revertConfig();
-    }
-    
-    void revertConfig()
-    {
-        setLayerCount(colorGradationGetPartCount(_gradation));
-    }
-    
-    void configChangeEvent()
-    {
-        colorGradationSetPart(_gradation, currentLayer(), _layer);
-        
-        BaseForm::configChangeEvent();
-    }
-    
-    void layerAddedEvent()
-    {
-        if (colorGradationAddPart(_gradation) >= 0)
-        {
-            BaseForm::layerAddedEvent();
-        }
-    }
-
-    void layerDeletedEvent(int layer)
-    {
-        colorGradationDelPart(_gradation, layer);
-
-        BaseForm::layerDeletedEvent(layer);
-    }
-
-    void layerSelectedEvent(int layer)
-    {
-        _layer = colorGradationGetPart(_gradation, layer);
-
-        BaseForm::layerSelectedEvent(layer);
-    }
-
-private:
-    ColorGradation* _gradation;
-    ColorGradationPart _layer;
-};
+#include "widgetcurveeditor.h"
 
 /**************** Dialog ****************/
 DialogColorGradation::DialogColorGradation(QWidget *parent, ColorGradation* gradation):
     QDialog(parent)
 {
-    QWidget* preview;
-            
     _base = gradation;
     _current = colorGradationCreate();
-    _current = *_base;
+    colorGradationCopy(_base, _current);
 
     setLayout(new QHBoxLayout());
     
-    preview = new QWidget(this);
-    layout()->addWidget(preview);
-    
-    _form = new FormColorGradation(this, &_current);
-    layout()->addWidget(_form);
+    _curve_editor = new WidgetCurveEditor(this);
+    layout()->addWidget(_curve_editor);
     
     /*QObject::connect(button, SIGNAL(clicked()), this, SLOT(accept()));
     QObject::connect(button, SIGNAL(clicked()), this, SLOT(revert()));
@@ -133,6 +36,7 @@ DialogColorGradation::DialogColorGradation(QWidget *parent, ColorGradation* grad
 
 DialogColorGradation::~DialogColorGradation()
 {
+    colorGradationDelete(_current);
 }
 
 bool DialogColorGradation::getGradation(QWidget* parent, ColorGradation* gradation)
@@ -154,18 +58,17 @@ void DialogColorGradation::closeEvent(QCloseEvent* e)
 
 void DialogColorGradation::accept()
 {
-    *_base = _current;
+    colorGradationCopy(_current, _base);
     QDialog::accept();
 }
 
 void DialogColorGradation::revert()
 {
-    _current = *_base;
-
+    colorGradationCopy(_base, _current);
     revertToCurrent();
 }
 
 void DialogColorGradation::revertToCurrent()
 {
-    _form->revertConfig();
+    // TODO
 }
diff --git a/gui_qt/dialogcolorgradation.h b/gui_qt/dialogcolorgradation.h
index 6c908e7..0205120 100644
--- a/gui_qt/dialogcolorgradation.h
+++ b/gui_qt/dialogcolorgradation.h
@@ -3,6 +3,7 @@
 
 #include <QDialog>
 #include "baseform.h"
+#include "widgetcurveeditor.h"
 
 #include "../lib_paysages/color.h"
 
@@ -27,8 +28,8 @@ private:
 
 private:
     ColorGradation* _base;
-    ColorGradation _current;
-    BaseForm* _form;
+    ColorGradation* _current;
+    WidgetCurveEditor* _curve_editor;
 };
 
 #endif
diff --git a/gui_qt/formsky.cpp b/gui_qt/formsky.cpp
index 307ec86..c96facb 100644
--- a/gui_qt/formsky.cpp
+++ b/gui_qt/formsky.cpp
@@ -86,10 +86,10 @@ FormSky::FormSky(QWidget *parent):
     addPreview(previewEast, QString(tr("East preview")));
 
     addInputDouble(tr("Day time"), &_definition.daytime, 0.0, 1.0, 0.01, 0.1);
-    addInputColorGradation(tr("Sun color"), &_definition.sun_color);
+    addInputColorGradation(tr("Sun color"), _definition.sun_color);
     addInputDouble(tr("Sun radius"), &_definition.sun_radius, 0.0, 0.3, 0.01, 0.03);
-    addInputColorGradation(tr("Zenith color"), &_definition.zenith_color);
-    addInputColorGradation(tr("Haze color"), &_definition.haze_color);
+    addInputColorGradation(tr("Zenith color"), _definition.zenith_color);
+    addInputColorGradation(tr("Haze color"), _definition.haze_color);
     addInputDouble(tr("Haze height"), &_definition.haze_height, 0.0, 1.0, 0.01, 0.1);
     addInputDouble(tr("Haze smoothing"), &_definition.haze_smoothing, 0.0, 1.0, 0.01, 0.1);
 
diff --git a/gui_qt/inputcolorgradation.cpp b/gui_qt/inputcolorgradation.cpp
index 0741771..1a281b8 100644
--- a/gui_qt/inputcolorgradation.cpp
+++ b/gui_qt/inputcolorgradation.cpp
@@ -10,12 +10,11 @@
 class ColorGradationPreview:public QWidget
 {
 public:
-    ColorGradationPreview(QWidget* parent, ColorGradation* gradation):
-        QWidget(parent),
-        gradation(gradation)
+    ColorGradationPreview(QWidget* parent, ColorGradation* gradation) : QWidget(parent)
     {
+        this->gradation = gradation;
     }
-
+    
     void paintEvent(QPaintEvent* event)
     {
         QPainter painter(this);
@@ -32,10 +31,10 @@ public:
     ColorGradation* gradation;
 };
 
-InputColorGradation::InputColorGradation(QWidget* form, QString label, ColorGradation* value):
-    BaseInput(form, label),
-    _value(value)
+InputColorGradation::InputColorGradation(QWidget* form, QString label, ColorGradation* value) : BaseInput(form, label)
 {
+    _value = value;
+            
     _preview = new ColorGradationPreview(form, value);
     _preview->setMinimumSize(200, 20);
 
@@ -63,12 +62,14 @@ void InputColorGradation::revert()
 
 void InputColorGradation::editGradation()
 {
-    ColorGradation gradation;
+    ColorGradation* gradation;
     
-    gradation = *_value;
-    if (DialogColorGradation::getGradation(_preview, &gradation))
+    gradation = colorGradationCreate();
+    colorGradationCopy(_value, gradation);
+    if (DialogColorGradation::getGradation(_preview, gradation))
     {
-        *_value = gradation;
+        colorGradationCopy(gradation, _value);
         applyValue();
     }
+    colorGradationDelete(gradation);
 }
diff --git a/gui_qt/inputcolorgradation.h b/gui_qt/inputcolorgradation.h
index fe6ff5b..42bdbd7 100644
--- a/gui_qt/inputcolorgradation.h
+++ b/gui_qt/inputcolorgradation.h
@@ -4,7 +4,7 @@
 #include <QWidget>
 #include "baseinput.h"
 
-#include "../lib_paysages/shared/types.h"
+#include "../lib_paysages/color.h"
 
 class InputColorGradation:public BaseInput
 {
diff --git a/gui_qt/mainwindow.cpp b/gui_qt/mainwindow.cpp
index 8015379..df7a856 100644
--- a/gui_qt/mainwindow.cpp
+++ b/gui_qt/mainwindow.cpp
@@ -94,9 +94,9 @@ MainWindow::MainWindow(QWidget *parent) :
     tabs->addTab(form, tr("Clouds"));
     QObject::connect(form, SIGNAL(configApplied()), this, SLOT(refreshAll()));
 
-    form = new FormLighting(tabs);
+    /*form = new FormLighting(tabs);
     tabs->addTab(form, tr("Lighting"));
-    QObject::connect(form, SIGNAL(configApplied()), this, SLOT(refreshAll()));
+    QObject::connect(form, SIGNAL(configApplied()), this, SLOT(refreshAll()));*/
 
     form = new FormRender(tabs);
     tabs->addTab(form, tr("Render"));
diff --git a/gui_qt/widgetcurveeditor.cpp b/gui_qt/widgetcurveeditor.cpp
new file mode 100644
index 0000000..9132810
--- /dev/null
+++ b/gui_qt/widgetcurveeditor.cpp
@@ -0,0 +1,32 @@
+#include "widgetcurveeditor.h"
+
+#include <QPainter>
+
+WidgetCurveEditor::WidgetCurveEditor(QWidget *parent) : QWidget(parent)
+{
+    _curve = curveCreate();
+    
+    setMinimumSize(500, 500);
+    setMaximumSize(500, 500);
+}
+
+WidgetCurveEditor::~WidgetCurveEditor()
+{
+    curveDelete(_curve);
+}
+
+void WidgetCurveEditor::paintEvent(QPaintEvent* event)
+{
+    double position, value;
+    
+    QPainter painter(this);
+    painter.fillRect(0, 0, 500, 500, QColor(255, 255, 255));
+    painter.setPen(QColor(255, 0, 0));
+    
+    for (int x = 0; x < 500; x++)
+    {
+        position = ((double)x) / 499.0;
+        value = curveGetValue(_curve, position);
+        painter.drawPoint(x, 499 - (int)(value * 499.0));
+    }
+}
diff --git a/gui_qt/widgetcurveeditor.h b/gui_qt/widgetcurveeditor.h
new file mode 100644
index 0000000..52139dd
--- /dev/null
+++ b/gui_qt/widgetcurveeditor.h
@@ -0,0 +1,22 @@
+#ifndef _PAYSAGES_QT_WIDGETCURVEEDITOR_H_
+#define _PAYSAGES_QT_WIDGETCURVEEDITOR_H_
+
+#include <QWidget>
+#include "../lib_paysages/curve.h"
+
+class WidgetCurveEditor : public QWidget
+{
+    Q_OBJECT
+    
+public:
+    WidgetCurveEditor(QWidget* parent);
+    ~WidgetCurveEditor();
+    
+protected:
+    void paintEvent(QPaintEvent* event);
+    
+private:
+    Curve* _curve;
+};
+
+#endif
diff --git a/i18n/paysages_fr.ts b/i18n/paysages_fr.ts
index 3ec95c3..38f4515 100644
--- a/i18n/paysages_fr.ts
+++ b/i18n/paysages_fr.ts
@@ -4,40 +4,34 @@
 <context>
     <name>BaseForm</name>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="33"/>
         <source>Layers : </source>
-        <translation>Niveaux :</translation>
+        <translation type="obsolete">Niveaux :</translation>
     </message>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="39"/>
         <source>Add layer</source>
-        <translation>Ajouter un niveau</translation>
+        <translation type="obsolete">Ajouter un niveau</translation>
     </message>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="43"/>
         <source>Delete layer</source>
-        <translation>Supprimer un niveau</translation>
+        <translation type="obsolete">Supprimer un niveau</translation>
     </message>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="73"/>
         <source>Apply</source>
-        <translation>Appliquer</translation>
+        <translation type="obsolete">Appliquer</translation>
     </message>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="76"/>
         <source>Revert</source>
-        <translation>Annuler les modifications</translation>
+        <translation type="obsolete">Annuler les modifications</translation>
     </message>
     <message>
-        <location filename="../gui_qt/baseform.cpp" line="239"/>
         <source>Layer %1</source>
-        <translation>Niveau %1</translation>
+        <translation type="obsolete">Niveau %1</translation>
     </message>
 </context>
 <context>
     <name>DialogColorGradation</name>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="129"/>
+        <location filename="../gui_qt/dialogcolorgradation.cpp" line="34"/>
         <source>Paysages 3D - Color gradation editor</source>
         <translation>Paysages 3D - Editeur de gradients de couleur</translation>
     </message>
@@ -245,34 +239,28 @@
 <context>
     <name>FormColorGradation</name>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="51"/>
         <source>Preview</source>
-        <translation>Aperçu</translation>
+        <translation type="obsolete">Aperçu</translation>
     </message>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="53"/>
         <source>Position</source>
-        <translation>Position</translation>
+        <translation type="obsolete">Position</translation>
     </message>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="54"/>
         <source>Color</source>
-        <translation>Couleur</translation>
+        <translation type="obsolete">Couleur</translation>
     </message>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="56"/>
         <source>Validate</source>
-        <translation>Valider</translation>
+        <translation type="obsolete">Valider</translation>
     </message>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="59"/>
         <source>Revert</source>
-        <translation>Recommencer</translation>
+        <translation type="obsolete">Recommencer</translation>
     </message>
     <message>
-        <location filename="../gui_qt/dialogcolorgradation.cpp" line="62"/>
         <source>Cancel</source>
-        <translation>Annuler</translation>
+        <translation type="obsolete">Annuler</translation>
     </message>
 </context>
 <context>
@@ -504,7 +492,7 @@
 <context>
     <name>InputColorGradation</name>
     <message>
-        <location filename="../gui_qt/inputcolorgradation.cpp" line="42"/>
+        <location filename="../gui_qt/inputcolorgradation.cpp" line="41"/>
         <source>Edit</source>
         <translation>Editer</translation>
     </message>
@@ -550,9 +538,8 @@
         <translation>Nuages</translation>
     </message>
     <message>
-        <location filename="../gui_qt/mainwindow.cpp" line="98"/>
         <source>Lighting</source>
-        <translation>Eclairage</translation>
+        <translation type="obsolete">Eclairage</translation>
     </message>
     <message>
         <location filename="../gui_qt/mainwindow.cpp" line="102"/>
diff --git a/lib_paysages/atmosphere.c b/lib_paysages/atmosphere.c
index 6d9ee0b..7bd18d8 100644
--- a/lib_paysages/atmosphere.c
+++ b/lib_paysages/atmosphere.c
@@ -78,7 +78,7 @@ void atmosphereValidateDefinition(AtmosphereDefinition* definition)
     {
         sky = skyCreateDefinition();
         sceneryGetSky(&sky);
-        definition->color = colorGradationGet(&sky.haze_color, sky.daytime);
+        definition->color = colorGradationGet(sky.haze_color, sky.daytime);
         skyDeleteDefinition(&sky);
     }
 }
diff --git a/lib_paysages/auto.c b/lib_paysages/auto.c
index 19450f9..8419906 100644
--- a/lib_paysages/auto.c
+++ b/lib_paysages/auto.c
@@ -108,23 +108,23 @@ void autoGenRealisticLandscape(int seed)
 
     /* Sky */
     sky = skyCreateDefinition();
-    colorGradationQuickAddRgba(&sky.sun_color, 0.3, 1.0, 0.91, 0.8, 1.0);
-    colorGradationQuickAddRgba(&sky.sun_color, 0.5, 1.0, 0.95, 0.9, 1.0);
-    colorGradationQuickAddRgba(&sky.sun_color, 0.7, 1.0, 0.91, 0.8, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.2, 0.03, 0.03, 0.05, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.25, 0.25, 0.33, 0.37, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.35, 0.52, 0.63, 0.8, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.65, 0.52, 0.63, 0.8, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.75, 0.25, 0.33, 0.37, 1.0);
-    colorGradationQuickAddRgba(&sky.zenith_color, 0.8, 0.03, 0.03, 0.05, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.2, 0.05, 0.05, 0.08, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.25, 0.55, 0.42, 0.42, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.3, 0.6, 0.6, 0.6, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.4, 0.92, 0.93, 1.0, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.6, 0.92, 0.93, 1.0, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.7, 0.6, 0.6, 0.8, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.75, 0.62, 0.50, 0.42, 1.0);
-    colorGradationQuickAddRgba(&sky.haze_color, 0.8, 0.05, 0.05, 0.08, 1.0);
+    colorGradationQuickAddRgb(sky.sun_color, 0.3, 1.0, 0.91, 0.8);
+    colorGradationQuickAddRgb(sky.sun_color, 0.5, 1.0, 0.95, 0.9);
+    colorGradationQuickAddRgb(sky.sun_color, 0.7, 1.0, 0.91, 0.8);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.2, 0.03, 0.03, 0.05);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.25, 0.25, 0.33, 0.37);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.35, 0.52, 0.63, 0.8);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.65, 0.52, 0.63, 0.8);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.75, 0.25, 0.33, 0.37);
+    colorGradationQuickAddRgb(sky.zenith_color, 0.8, 0.03, 0.03, 0.05);
+    colorGradationQuickAddRgb(sky.haze_color, 0.2, 0.05, 0.05, 0.08);
+    colorGradationQuickAddRgb(sky.haze_color, 0.25, 0.55, 0.42, 0.42);
+    colorGradationQuickAddRgb(sky.haze_color, 0.3, 0.6, 0.6, 0.6);
+    colorGradationQuickAddRgb(sky.haze_color, 0.4, 0.92, 0.93, 1.0);
+    colorGradationQuickAddRgb(sky.haze_color, 0.6, 0.92, 0.93, 1.0);
+    colorGradationQuickAddRgb(sky.haze_color, 0.7, 0.6, 0.6, 0.8);
+    colorGradationQuickAddRgb(sky.haze_color, 0.75, 0.62, 0.50, 0.42);
+    colorGradationQuickAddRgb(sky.haze_color, 0.8, 0.05, 0.05, 0.08);
     sky.daytime = 0.0;
     sky.haze_height = 0.75;
     sky.haze_smoothing = 0.3;
diff --git a/lib_paysages/color.c b/lib_paysages/color.c
index f8a7470..af3740a 100644
--- a/lib_paysages/color.c
+++ b/lib_paysages/color.c
@@ -5,6 +5,7 @@
 #include <string.h>
 #include "shared/constants.h"
 #include "tools.h"
+#include "curve.h"
 
 Color COLOR_TRANSPARENT = {0.0, 0.0, 0.0, 0.0};
 Color COLOR_BLACK = {0.0, 0.0, 0.0, 1.0};
@@ -14,13 +15,12 @@ Color COLOR_BLUE = {0.0, 0.0, 1.0, 1.0};
 Color COLOR_WHITE = {1.0, 1.0, 1.0, 1.0};
 Color COLOR_GREY = {0.5, 0.5, 0.5, 1.0};
 
-ColorGradationPart COLORGRADATIONPART_NULL;
-
-void colorInit()
+struct ColorGradation
 {
-    COLORGRADATIONPART_NULL.col = COLOR_TRANSPARENT;
-    COLORGRADATIONPART_NULL.start = 0.0;
-}
+    Curve* red;
+    Curve* green;
+    Curve* blue;
+};
 
 void colorSave(FILE* f, Color* col)
 {
@@ -110,158 +110,106 @@ double colorGetValue(Color* col)
     return max;
 }
 
-ColorGradation colorGradationCreate()
+ColorGradation* colorGradationCreate()
 {
-    ColorGradation result;
-
-    result.nbparts = 0;
+    ColorGradation* result;
 
+    result = malloc(sizeof(ColorGradation));
+    result->red = curveCreate();
+    result->green = curveCreate();
+    result->blue = curveCreate();
+    
     return result;
 }
 
-int _part_compare(const void* part1, const void* part2)
+void colorGradationDelete(ColorGradation* gradation)
 {
-    if (((ColorGradationPart*)part1)->start > ((ColorGradationPart*)part2)->start)
-    {
-        return 1;
-    }
-    else
-    {
-        return -1;
-    }
+    curveDelete(gradation->red);
+    curveDelete(gradation->green);
+    curveDelete(gradation->blue);
+    free(gradation);
+}
+
+void colorGradationCopy(ColorGradation* source, ColorGradation* destination)
+{
+    curveCopy(source->red, destination->red);
+    curveCopy(source->green, destination->green);
+    curveCopy(source->blue, destination->blue);
 }
 
 void colorGradationSave(FILE* f, ColorGradation* gradation)
 {
-    int i;
-
-    toolsSaveInt(f, &gradation->nbparts);
-    for (i = 0; i < gradation->nbparts; i++)
-    {
-        toolsSaveDouble(f, &gradation->parts[i].start);
-        colorSave(f, &gradation->parts[i].col);
-    }
+    curveSave(f, gradation->red);
+    curveSave(f, gradation->green);
+    curveSave(f, gradation->blue);
 }
 
 void colorGradationLoad(FILE* f, ColorGradation* gradation)
 {
-    int i;
-
-    toolsLoadInt(f, &gradation->nbparts);
-    for (i = 0; i < gradation->nbparts; i++)
-    {
-        toolsLoadDouble(f, &gradation->parts[i].start);
-        colorLoad(f, &gradation->parts[i].col);
-    }
+    curveLoad(f, gradation->red);
+    curveLoad(f, gradation->green);
+    curveLoad(f, gradation->blue);
 }
 
-int colorGradationGetPartCount(ColorGradation* gradation)
+void colorGradationGetRedCurve(ColorGradation* gradation, Curve* curve)
 {
-    return gradation->nbparts;
+    curveCopy(gradation->red, curve);
 }
 
-int colorGradationAddPart(ColorGradation* gradation)
+void colorGradationGetGreenCurve(ColorGradation* gradation, Curve* curve)
 {
-    if (gradation->nbparts == MAX_COLORGRADATION_PARTS)
-    {
-        return -1;
-    }
-    else
-    {
-        return gradation->nbparts++;
-    }
+    curveCopy(gradation->green, curve);
 }
 
-void colorGradationDelPart(ColorGradation* gradation, int part)
+void colorGradationGetBlueCurve(ColorGradation* gradation, Curve* curve)
 {
-    if (part >= 0 && part < gradation->nbparts)
-    {
-        memmove(gradation->parts + part, gradation->parts + part + 1, sizeof(ColorGradationPart) * (gradation->nbparts - part - 1));
-        gradation->nbparts--;
-    }
+    curveCopy(gradation->blue, curve);
 }
 
-ColorGradationPart colorGradationGetPart(ColorGradation* gradation, int part)
+void colorGradationSetRedCurve(ColorGradation* gradation, Curve* curve)
 {
-    if (part >= 0 && part < gradation->nbparts)
-    {
-        return gradation->parts[part];
-    }
-    else
-    {
-        return COLORGRADATIONPART_NULL;
-    }
+    curveCopy(curve, gradation->red);
+    curveValidate(gradation->red);
 }
 
-void colorGradationSetPart(ColorGradation* gradation, int part, ColorGradationPart value)
+void colorGradationSetGreenCurve(ColorGradation* gradation, Curve* curve)
 {
-    if (part >= 0 && part < gradation->nbparts)
-    {
-        gradation->parts[part] = value;
-    }
+    curveCopy(curve, gradation->green);
+    curveValidate(gradation->green);
+}
+
+void colorGradationSetBlueCurve(ColorGradation* gradation, Curve* curve)
+{
+    curveCopy(curve, gradation->blue);
+    curveValidate(gradation->blue);
 }
 
 void colorGradationQuickAdd(ColorGradation* gradation, double value, Color* col)
 {
-    if (gradation->nbparts == MAX_COLORGRADATION_PARTS)
-    {
-        return;
-    }
-    else
-    {
-        gradation->parts[gradation->nbparts].start = value;
-        gradation->parts[gradation->nbparts].col = *col;
-
-        if (gradation->nbparts++ > 1)
-        {
-            qsort(gradation->parts, gradation->nbparts, sizeof(ColorGradationPart), _part_compare);
-        }
-    }
+    colorGradationQuickAddRgb(gradation, value, col->r, col->g, col->b);
 }
 
-void colorGradationQuickAddRgba(ColorGradation* gradation, double value, double r, double g, double b, double a)
+void colorGradationQuickAddRgb(ColorGradation* gradation, double value, double r, double g, double b)
 {
-    Color col;
-    col.r = r;
-    col.g = g;
-    col.b = b;
-    col.a = a;
-    colorGradationQuickAdd(gradation, value, &col);
+    curveQuickAddPoint(gradation->red, value, r);
+    curveValidate(gradation->red);
+
+    curveQuickAddPoint(gradation->green, value, g);
+    curveValidate(gradation->green);
+
+    curveQuickAddPoint(gradation->blue, value, b);
+    curveValidate(gradation->blue);
 }
 
 Color colorGradationGet(ColorGradation* gradation, double value)
 {
     Color result;
-    int i;
-    double fact;
 
-    if (gradation->nbparts == 0)
-    {
-        return COLOR_TRANSPARENT;
-    }
-    else if (gradation->nbparts == 1 || value <= gradation->parts[0].start)
-    {
-        return gradation->parts[0].col;
-    }
-    else if (value >= gradation->parts[gradation->nbparts - 1].start)
-    {
-        return gradation->parts[gradation->nbparts - 1].col;
-    }
-    else
-    {
-        for (i = 1; i < gradation->nbparts; i++)
-        {
-            if (value < gradation->parts[i].start)
-            {
-                fact = (value - gradation->parts[i - 1].start) / (gradation->parts[i].start - gradation->parts[i - 1].start);
-                result.r = gradation->parts[i - 1].col.r + (gradation->parts[i].col.r - gradation->parts[i - 1].col.r) * fact;
-                result.g = gradation->parts[i - 1].col.g + (gradation->parts[i].col.g - gradation->parts[i - 1].col.g) * fact;
-                result.b = gradation->parts[i - 1].col.b + (gradation->parts[i].col.b - gradation->parts[i - 1].col.b) * fact;
-                result.a = gradation->parts[i - 1].col.a + (gradation->parts[i].col.a - gradation->parts[i - 1].col.a) * fact;
-                return result;
-            }
-        }
-        return gradation->parts[gradation->nbparts - 1].col;
-    }
+    result.r = curveGetValue(gradation->red, value);
+    result.g = curveGetValue(gradation->green, value);
+    result.b = curveGetValue(gradation->blue, value);
+    result.a = 1.0;
+    
+    return result;
 }
 
diff --git a/lib_paysages/color.h b/lib_paysages/color.h
index b9a8527..416467a 100644
--- a/lib_paysages/color.h
+++ b/lib_paysages/color.h
@@ -3,33 +3,46 @@
 
 #include "shared/types.h"
 #include "shared/constants.h"
+#include "curve.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-void colorInit();
-    
+/* Color */
 void colorSave(FILE* f, Color* col);
 void colorLoad(FILE* f, Color* col);
+
 unsigned int colorTo32BitRGBA(Color* col);
 unsigned int colorTo32BitBGRA(Color* col);
 unsigned int colorTo32BitARGB(Color* col);
 unsigned int colorTo32BitABGR(Color* col);
+
 void colorMask(Color* base, Color* mask);
 double colorNormalize(Color* col);
 double colorGetValue(Color* col);
 
-ColorGradation colorGradationCreate();
+/* ColorGradation */
+typedef struct ColorGradation ColorGradation;
+
+ColorGradation* colorGradationCreate();
+void colorGradationDelete(ColorGradation* gradation);
+void colorGradationCopy(ColorGradation* source, ColorGradation* destination);
+
 void colorGradationSave(FILE* f, ColorGradation* gradation);
 void colorGradationLoad(FILE* f, ColorGradation* gradation);
-int colorGradationGetPartCount(ColorGradation* gradation);
-int colorGradationAddPart(ColorGradation* gradation);
-void colorGradationDelPart(ColorGradation* gradation, int part);
-ColorGradationPart colorGradationGetPart(ColorGradation* gradation, int part);
-void colorGradationSetPart(ColorGradation* gradation, int part, ColorGradationPart value);
+
+void colorGradationGetRedCurve(ColorGradation* gradation, Curve* curve);
+void colorGradationGetGreenCurve(ColorGradation* gradation, Curve* curve);
+void colorGradationGetBlueCurve(ColorGradation* gradation, Curve* curve);
+
+void colorGradationSetRedCurve(ColorGradation* gradation, Curve* curve);
+void colorGradationSetGreenCurve(ColorGradation* gradation, Curve* curve);
+void colorGradationSetBlueCurve(ColorGradation* gradation, Curve* curve);
+
 void colorGradationQuickAdd(ColorGradation* gradation, double value, Color* col);
-void colorGradationQuickAddRgba(ColorGradation* gradation, double value, double r, double g, double b, double a);
+void colorGradationQuickAddRgb(ColorGradation* gradation, double value, double r, double g, double b);
+
 Color colorGradationGet(ColorGradation* gradation, double value);
 
 #ifdef __cplusplus
diff --git a/lib_paysages/curve.c b/lib_paysages/curve.c
new file mode 100644
index 0000000..e03f879
--- /dev/null
+++ b/lib_paysages/curve.c
@@ -0,0 +1,148 @@
+#include "curve.h"
+
+#include <stdlib.h>
+#include "tools.h"
+
+#define MAX_NB_POINTS 40
+
+struct Curve
+{
+    int nbpoints;
+    CurvePoint points[MAX_NB_POINTS];
+};
+
+Curve* curveCreate()
+{
+    Curve* result;
+    
+    result = malloc(sizeof(Curve));
+    result->nbpoints = 0;
+    
+    return result;
+}
+
+void curveDelete(Curve* curve)
+{
+    free(curve);
+}
+
+void curveCopy(Curve* source, Curve* destination)
+{
+    *destination = *source;
+}
+
+void curveSave(FILE* f, Curve* curve)
+{
+    int i;
+    
+    toolsSaveInt(f, &curve->nbpoints);
+    for (i = 0; i < curve->nbpoints; i++)
+    {
+        toolsSaveDouble(f, &curve->points[i].position);
+        toolsSaveDouble(f, &curve->points[i].value);
+    }
+}
+
+void curveLoad(FILE* f, Curve* curve)
+{
+    int i;
+    
+    toolsLoadInt(f, &curve->nbpoints);
+    for (i = 0; i < curve->nbpoints; i++)
+    {
+        toolsLoadDouble(f, &curve->points[i].position);
+        toolsLoadDouble(f, &curve->points[i].value);
+    }
+}
+
+void curveClear(Curve* curve)
+{
+    curve->nbpoints = 0;
+}
+
+int curveAddPoint(Curve* curve, CurvePoint* point)
+{
+    if (curve->nbpoints < MAX_NB_POINTS)
+    {
+        curve->points[curve->nbpoints] = *point;
+        return curve->nbpoints++;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+int curveQuickAddPoint(Curve* curve, double position, double value)
+{
+    CurvePoint point;
+    
+    point.position = position;
+    point.value = value;
+    
+    return curveAddPoint(curve, &point);
+}
+
+int curveGetPointCount(Curve* curve)
+{
+    return curve->nbpoints;
+}
+
+void curveGetPoint(Curve* curve, int number, CurvePoint* point)
+{
+    if (number >= 0 && number < curve->nbpoints)
+    {
+        *point = curve->points[number];
+    }
+}
+
+int _point_compare(const void* part1, const void* part2)
+{
+    if (((CurvePoint*)part1)->position > ((CurvePoint*)part2)->position)
+    {
+        return 1;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+void curveValidate(Curve* curve)
+{
+    if (curve->nbpoints > 1)
+    {
+        qsort(curve->points, curve->nbpoints, sizeof(CurvePoint), _point_compare);
+    }
+}
+
+double curveGetValue(Curve* curve, double position)
+{
+    int i;
+    double fact;
+
+    if (curve->nbpoints == 0)
+    {
+        return 0.0;
+    }
+    else if (curve->nbpoints == 1 || position <= curve->points[0].position)
+    {
+        return curve->points[0].value;
+    }
+    else if (position >= curve->points[curve->nbpoints - 1].position)
+    {
+        return curve->points[curve->nbpoints - 1].value;
+    }
+    else
+    {
+        for (i = 1; i < curve->nbpoints; i++)
+        {
+            if (position < curve->points[i].position)
+            {
+                fact = (position - curve->points[i - 1].position) / (curve->points[i].position - curve->points[i - 1].position);
+                return curve->points[i - 1].value + (curve->points[i].value - curve->points[i - 1].value) * fact;
+            }
+        }
+        return curve->points[curve->nbpoints - 1].value;
+    }
+}
diff --git a/lib_paysages/curve.h b/lib_paysages/curve.h
new file mode 100644
index 0000000..1f1642c
--- /dev/null
+++ b/lib_paysages/curve.h
@@ -0,0 +1,36 @@
+#ifndef _PAYSAGES_CURVE_H_
+#define _PAYSAGES_CURVE_H_
+
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+    double position;
+    double value;
+} CurvePoint;
+typedef struct Curve Curve;
+
+Curve* curveCreate();
+void curveDelete(Curve* curve);
+void curveCopy(Curve* source, Curve* destination);
+
+void curveSave(FILE* f, Curve* curve);
+void curveLoad(FILE* f, Curve* curve);
+
+void curveClear(Curve* curve);
+int curveAddPoint(Curve* curve, CurvePoint* point);
+int curveQuickAddPoint(Curve* curve, double position, double value);
+int curveGetPointCount(Curve* curve);
+void curveGetPoint(Curve* curve, int number, CurvePoint* point);
+void curveValidate(Curve* curve);
+
+double curveGetValue(Curve* curve, double position);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/lib_paysages/main.c b/lib_paysages/main.c
index a38bee4..b1b3cb2 100644
--- a/lib_paysages/main.c
+++ b/lib_paysages/main.c
@@ -22,7 +22,6 @@ void paysagesInit()
     ilInit();
     iluInit();
 
-    colorInit();
     sceneryInit();
     renderInit();
 
diff --git a/lib_paysages/shared/types.h b/lib_paysages/shared/types.h
index 6b9aafb..0905215 100644
--- a/lib_paysages/shared/types.h
+++ b/lib_paysages/shared/types.h
@@ -42,18 +42,6 @@ typedef struct
     double a;
 } Color;
 
-#define MAX_COLORGRADATION_PARTS 10
-typedef struct
-{
-    double start;
-    Color col;
-} ColorGradationPart;
-typedef struct
-{
-    int nbparts;
-    ColorGradationPart parts[MAX_COLORGRADATION_PARTS];
-} ColorGradation;
-
 struct RenderFragment;
 struct Renderer;
 
diff --git a/lib_paysages/sky.c b/lib_paysages/sky.c
index cd9876e..4f8a17a 100644
--- a/lib_paysages/sky.c
+++ b/lib_paysages/sky.c
@@ -25,10 +25,10 @@ void skyQuit()
 void skySave(FILE* f, SkyDefinition* definition)
 {
     toolsSaveDouble(f, &definition->daytime);
-    colorGradationSave(f, &definition->sun_color);
+    colorGradationSave(f, definition->sun_color);
     toolsSaveDouble(f, &definition->sun_radius);
-    colorGradationSave(f, &definition->zenith_color);
-    colorGradationSave(f, &definition->haze_color);
+    colorGradationSave(f, definition->zenith_color);
+    colorGradationSave(f, definition->haze_color);
     toolsSaveDouble(f, &definition->haze_height);
     toolsSaveDouble(f, &definition->haze_smoothing);
 }
@@ -36,10 +36,10 @@ void skySave(FILE* f, SkyDefinition* definition)
 void skyLoad(FILE* f, SkyDefinition* definition)
 {
     toolsLoadDouble(f, &definition->daytime);
-    colorGradationLoad(f, &definition->sun_color);
+    colorGradationLoad(f, definition->sun_color);
     toolsLoadDouble(f, &definition->sun_radius);
-    colorGradationLoad(f, &definition->zenith_color);
-    colorGradationLoad(f, &definition->haze_color);
+    colorGradationLoad(f, definition->zenith_color);
+    colorGradationLoad(f, definition->haze_color);
     toolsLoadDouble(f, &definition->haze_height);
     toolsLoadDouble(f, &definition->haze_smoothing);
 
@@ -65,25 +65,36 @@ SkyDefinition skyCreateDefinition()
 
 void skyDeleteDefinition(SkyDefinition* definition)
 {
+    colorGradationDelete(definition->sun_color);
+    colorGradationDelete(definition->zenith_color);
+    colorGradationDelete(definition->haze_color);
 }
 
 void skyCopyDefinition(SkyDefinition* source, SkyDefinition* destination)
 {
-    *destination = *source;
+    destination->daytime = source->daytime;
+    destination->sun_radius = source->sun_radius;
+    destination->haze_height = source->haze_height;
+    destination->haze_smoothing = source->haze_smoothing;
+    
+    colorGradationCopy(source->sun_color, destination->sun_color);
+    colorGradationCopy(source->zenith_color, destination->zenith_color);
+    colorGradationCopy(source->haze_color, destination->haze_color);
+    colorGradationCopy(source->_sky_gradation, destination->_sky_gradation);
 }
 
 void skyValidateDefinition(SkyDefinition* definition)
 {
     Color zenith, haze;
 
-    zenith = colorGradationGet(&definition->zenith_color, definition->daytime);
-    haze = colorGradationGet(&definition->haze_color, definition->daytime);
+    zenith = colorGradationGet(definition->zenith_color, definition->daytime);
+    haze = colorGradationGet(definition->haze_color, definition->daytime);
 
     definition->_sky_gradation = colorGradationCreate();
-    colorGradationQuickAdd(&definition->_sky_gradation, 0.0, &haze);
-    colorGradationQuickAdd(&definition->_sky_gradation, definition->haze_height - definition->haze_smoothing, &haze);
-    colorGradationQuickAdd(&definition->_sky_gradation, definition->haze_height, &zenith);
-    colorGradationQuickAdd(&definition->_sky_gradation, 1.0, &zenith);
+    colorGradationQuickAdd(definition->_sky_gradation, 0.0, &haze);
+    colorGradationQuickAdd(definition->_sky_gradation, definition->haze_height - definition->haze_smoothing, &haze);
+    colorGradationQuickAdd(definition->_sky_gradation, definition->haze_height, &zenith);
+    colorGradationQuickAdd(definition->_sky_gradation, 1.0, &zenith);
 }
 
 int skyGetLights(SkyDefinition* sky, LightDefinition* lights, int max_lights)
@@ -103,7 +114,7 @@ int skyGetLights(SkyDefinition* sky, LightDefinition* lights, int max_lights)
     {
         /* Light from the sun */
         lights[0].direction = v3Scale(sun_direction, -1.0);
-        lights[0].color = colorGradationGet(&sky->sun_color, sky->daytime);
+        lights[0].color = colorGradationGet(sky->sun_color, sky->daytime);
         lights[0].reflection = 1.0;
         lights[0].filtered = 1;
         lights[0].masked = 1;
@@ -115,7 +126,7 @@ int skyGetLights(SkyDefinition* sky, LightDefinition* lights, int max_lights)
             lights[1].direction.x = 0.0;
             lights[1].direction.y = -1.0;
             lights[1].direction.z = 0.0;
-            lights[1].color = colorGradationGet(&sky->zenith_color, sky->daytime);
+            lights[1].color = colorGradationGet(sky->zenith_color, sky->daytime);
             lights[1].color.r *= 0.6;
             lights[1].color.g *= 0.6;
             lights[1].color.b *= 0.6;
@@ -144,11 +155,11 @@ Color skyGetColor(SkyDefinition* definition, Renderer* renderer, Vector3 eye, Ve
     look = v3Normalize(look);
     dist = v3Norm(v3Sub(look, sun_position));
 
-    sky_color = colorGradationGet(&definition->_sky_gradation, look.y * 0.5 + 0.5);
+    sky_color = colorGradationGet(definition->_sky_gradation, look.y * 0.5 + 0.5);
     if (dist < definition->sun_radius)
     {
         dist = dist / definition->sun_radius;
-        sun_color = colorGradationGet(&definition->sun_color, definition->daytime);
+        sun_color = colorGradationGet(definition->sun_color, definition->daytime);
         if (dist < 0.9)
         {
             return sun_color;
diff --git a/lib_paysages/sky.h b/lib_paysages/sky.h
index d88a2d5..86079f6 100644
--- a/lib_paysages/sky.h
+++ b/lib_paysages/sky.h
@@ -2,6 +2,7 @@
 #define _PAYSAGES_SKY_H_
 
 #include "shared/types.h"
+#include "color.h"
 #include "lighting.h"
 #include <stdio.h>
 
@@ -12,13 +13,13 @@ extern "C" {
 typedef struct
 {
     double daytime;
-    ColorGradation sun_color;
+    ColorGradation* sun_color;
     double sun_radius;
-    ColorGradation zenith_color;
-    ColorGradation haze_color;
+    ColorGradation* zenith_color;
+    ColorGradation* haze_color;
     double haze_height;
     double haze_smoothing;
-    ColorGradation _sky_gradation;
+    ColorGradation* _sky_gradation;
 } SkyDefinition;
 
 void skyInit();