diff --git a/TODO b/TODO
index 89a81eb..c29fc65 100644
--- a/TODO
+++ b/TODO
@@ -3,6 +3,7 @@ Technlology Preview 2 :
 - Streamline the definition system, with undo and events.
 - Implement copy-on-write on definitions (to avoid copying whole heightmaps for instance).
 - Add clouds to OpenGL with 3d textures.
+- Refactor medium traversal to unify clouds, atmosphere and god rays.
 - Fix potential holes in land rendering (OpenGL and software).
 - Fix polygon culling near the camera in low-res renders (automatic tessellation ?).
 - Fix sun size not being consistent between opengl and software
diff --git a/src/basics/Interpolation.cpp b/src/basics/Interpolation.cpp
index 9268131..9ea3c6c 100644
--- a/src/basics/Interpolation.cpp
+++ b/src/basics/Interpolation.cpp
@@ -11,3 +11,17 @@ double Interpolation::bicubic(double stencil[16], double x, double y)
 
     return Interpolation::cubic(buf_cubic_y, y);
 }
+
+double Interpolation::bilinear(double p[4], double x, double y)
+{
+    double e1 = linear(p[0], p[1], x);
+    double e2 = linear(p[3], p[2], x);
+    return Interpolation::linear(e1, e2, y);
+}
+
+double Interpolation::trilinear(double p[8], double x, double y, double z)
+{
+    double f1 = bilinear(p, x, y);
+    double f2 = bilinear(p + 4, x, y);
+    return Interpolation::linear(f1, f2, z);
+}
diff --git a/src/basics/Interpolation.h b/src/basics/Interpolation.h
index 0c4043c..77f35c5 100644
--- a/src/basics/Interpolation.h
+++ b/src/basics/Interpolation.h
@@ -9,6 +9,13 @@ namespace basics {
 class BASICSSHARED_EXPORT Interpolation
 {
 public:
+    static inline double linear(double p1, double p2, double x)
+    {
+        return p1 + x * (p2 - p1);
+    }
+    static double bilinear(double p[4], double x, double y);
+    static double trilinear(double p[8], double x, double y, double z);
+
     static inline double cubic(double p[4], double x)
     {
         return p[1] + 0.5 * x * (p[2] - p[0] + x * (2.0 * p[0] - 5.0 * p[1] + 4.0 * p[2] - p[3] + x * (3.0 * (p[1] - p[2]) + p[3] - p[0])));
diff --git a/src/basics/SpaceSegment.h b/src/basics/SpaceSegment.h
index 4abfe86..a7ffd8b 100644
--- a/src/basics/SpaceSegment.h
+++ b/src/basics/SpaceSegment.h
@@ -20,6 +20,10 @@ public:
     inline Vector3 getStart() const {return start;}
     inline Vector3 getEnd() const {return end;}
 
+    inline double getXDiff() const {return end.x - start.x;}
+    inline double getYDiff() const {return end.y - start.y;}
+    inline double getZDiff() const {return end.z - start.z;}
+
     /*!
      * \brief Keep only the intersection with a slice orthogonal to the Y axis.
      * \return true if a segment remains
diff --git a/src/definition/AtmosphereDefinition.cpp b/src/definition/AtmosphereDefinition.cpp
index cd7935f..e96c8cd 100644
--- a/src/definition/AtmosphereDefinition.cpp
+++ b/src/definition/AtmosphereDefinition.cpp
@@ -3,10 +3,12 @@
 #include "PackStream.h"
 #include "RandomGenerator.h"
 #include "FloatNode.h"
+#include "GodRaysDefinition.h"
 
 AtmosphereDefinition::AtmosphereDefinition(DefinitionNode* parent):
     DefinitionNode(parent, "atmosphere", "atmosphere")
 {
+    godrays = new GodRaysDefinition(this);
     daytime = new FloatNode(this, "daytime");
     humidity = new FloatNode(this, "humidity");
     sun_radius = new FloatNode(this, "sun_radius");
diff --git a/src/definition/AtmosphereDefinition.h b/src/definition/AtmosphereDefinition.h
index 0d61340..20f43ee 100644
--- a/src/definition/AtmosphereDefinition.h
+++ b/src/definition/AtmosphereDefinition.h
@@ -45,6 +45,7 @@ public:
 
     virtual void copy(DefinitionNode* destination) const override;
 
+    inline GodRaysDefinition *childGodRays() const {return godrays;}
     inline FloatNode *propDayTime() const {return daytime;}
     inline FloatNode *propHumidity() const {return humidity;}
     inline FloatNode *propSunRadius() const {return sun_radius;}
@@ -78,6 +79,7 @@ public:
     std::vector<Star> stars;
 
 private:
+    GodRaysDefinition *godrays;
     FloatNode *humidity;
     FloatNode *daytime;
     FloatNode *sun_radius;
diff --git a/src/definition/GodRaysDefinition.cpp b/src/definition/GodRaysDefinition.cpp
new file mode 100644
index 0000000..94ec938
--- /dev/null
+++ b/src/definition/GodRaysDefinition.cpp
@@ -0,0 +1,12 @@
+#include "GodRaysDefinition.h"
+
+#include "FloatNode.h"
+
+GodRaysDefinition::GodRaysDefinition(DefinitionNode *parent):
+    DefinitionNode(parent, "godrays", "godrays")
+{
+    penetration = new FloatNode(this, "penetration", 0.01);
+    resistance = new FloatNode(this, "resistance", 0.3);
+    boost = new FloatNode(this, "boost", 8.0);
+}
+
diff --git a/src/definition/GodRaysDefinition.h b/src/definition/GodRaysDefinition.h
new file mode 100644
index 0000000..52775ec
--- /dev/null
+++ b/src/definition/GodRaysDefinition.h
@@ -0,0 +1,29 @@
+#ifndef GODRAYSDEFINITION_H
+#define GODRAYSDEFINITION_H
+
+#include "definition_global.h"
+
+#include "DefinitionNode.h"
+
+namespace paysages {
+namespace definition {
+
+class DEFINITIONSHARED_EXPORT GodRaysDefinition: public DefinitionNode
+{
+public:
+    GodRaysDefinition(DefinitionNode *parent);
+
+    inline FloatNode *propPenetration() const {return penetration;}
+    inline FloatNode *propResistance() const {return resistance;}
+    inline FloatNode *propBoost() const {return boost;}
+
+private:
+    FloatNode *penetration;
+    FloatNode *resistance;
+    FloatNode *boost;
+};
+
+}
+}
+
+#endif // GODRAYSDEFINITION_H
diff --git a/src/definition/definition.pro b/src/definition/definition.pro
index 7105ccf..c831134 100644
--- a/src/definition/definition.pro
+++ b/src/definition/definition.pro
@@ -37,7 +37,8 @@ SOURCES += \
     DiffManager.cpp \
     DefinitionWatcher.cpp \
     IntNode.cpp \
-    IntDiff.cpp
+    IntDiff.cpp \
+    GodRaysDefinition.cpp
 
 HEADERS +=\
         definition_global.h \
@@ -64,7 +65,8 @@ HEADERS +=\
     DiffManager.h \
     DefinitionWatcher.h \
     IntNode.h \
-    IntDiff.h
+    IntDiff.h \
+    GodRaysDefinition.h
 
 unix:!symbian {
     maemo5 {
diff --git a/src/definition/definition_global.h b/src/definition/definition_global.h
index 9f2d446..e2e6903 100644
--- a/src/definition/definition_global.h
+++ b/src/definition/definition_global.h
@@ -30,6 +30,7 @@ namespace definition {
     class CloudsDefinition;
     class CloudLayerDefinition;
     class AtmosphereDefinition;
+    class GodRaysDefinition;
     class TexturesDefinition;
     class TextureLayerDefinition;
     class TerrainDefinition;
diff --git a/src/interface/commandline/tests.cpp b/src/interface/commandline/tests.cpp
index d8786d1..6260484 100644
--- a/src/interface/commandline/tests.cpp
+++ b/src/interface/commandline/tests.cpp
@@ -5,11 +5,17 @@
 #include "TerrainDefinition.h"
 #include "AtmosphereDefinition.h"
 #include "TexturesDefinition.h"
+#include "GodRaysDefinition.h"
 #include "TextureLayerDefinition.h"
 #include "WaterDefinition.h"
 #include "SurfaceMaterial.h"
 #include "FloatNode.h"
 #include "SkyRasterizer.h"
+#include "CloudsDefinition.h"
+#include "LightComponent.h"
+#include "LightingManager.h"
+#include "LightFilter.h"
+#include "GodRaysSampler.h"
 
 #include <sstream>
 
@@ -103,10 +109,94 @@ static void testCloudQuality()
     }
 }
 
+static void testGodRays()
+{
+    class TestLightFilter: public LightFilter
+    {
+        virtual bool applyLightFilter(LightComponent &light, const Vector3 &at) override
+        {
+            if (Vector3(0.0, 100.0, 0.0).sub(at).normalize().y > 0.97)
+            {
+                light.color = COLOR_BLACK;
+                return false;
+            }
+            else
+            {
+                return true;
+            }
+        }
+    };
+    class TestRenderer: public SoftwareCanvasRenderer
+    {
+    public:
+        TestRenderer(Scenery *scenery): SoftwareCanvasRenderer(scenery) {}
+    private:
+        virtual void prepare() override
+        {
+            SoftwareRenderer::prepare();
+
+            getLightingManager()->clearSources();
+            getLightingManager()->addStaticLight(LightComponent(COLOR_WHITE, VECTOR_DOWN));
+            getGodRaysSampler()->setAltitudes(0.0, 30.0);
+            getGodRaysSampler()->reset();
+        }
+    };
+
+    Scenery scenery;
+    scenery.autoPreset(63);
+    scenery.getAtmosphere()->setDayTime(12);
+    scenery.getCamera()->setLocation(Vector3(0.0, 1.0, -50.0));
+    scenery.getCamera()->setTarget(Vector3(0.0, 15.0, 0.0));
+    scenery.getTerrain()->height = 0.0;
+    scenery.getTerrain()->validate();
+    scenery.getClouds()->clear();
+
+    TestRenderer renderer(&scenery);
+    renderer.setSize(500, 300);
+    SkyRasterizer *rasterizer = new SkyRasterizer(&renderer, renderer.getProgressHelper(), 0);
+    renderer.setSoloRasterizer(rasterizer);
+    TestLightFilter filter;
+    renderer.getLightingManager()->clearFilters();
+    renderer.getLightingManager()->registerFilter(&filter);
+
+    // quality
+    for (int i = 0; i < 6; i++)
+    {
+        renderer.setQuality((double)i / 5.0);
+        rasterizer->setQuality(0.2);
+        startTestRender(&renderer, "god_rays_quality", i);
+    }
+    renderer.setQuality(0.5);
+
+    // penetration
+    for (int i = 0; i < 3; i++)
+    {
+        scenery.getAtmosphere()->childGodRays()->propPenetration()->setValue(0.01 + 0.02 * (double)i);
+        startTestRender(&renderer, "god_rays_penetration", i);
+    }
+
+    // resistance
+    scenery.getAtmosphere()->childGodRays()->propPenetration()->setValue(0.01);
+    for (int i = 0; i < 3; i++)
+    {
+        scenery.getAtmosphere()->childGodRays()->propResistance()->setValue(0.1 + 0.1 * (double)i);
+        startTestRender(&renderer, "god_rays_resistance", i);
+    }
+
+    // boost
+    scenery.getAtmosphere()->childGodRays()->propResistance()->setValue(0.3);
+    for (int i = 0; i < 3; i++)
+    {
+        scenery.getAtmosphere()->childGodRays()->propBoost()->setValue(2.0 + 4.0 * (double)i);
+        startTestRender(&renderer, "god_rays_boost", i);
+    }
+}
+
 void runTestSuite()
 {
     testGroundShadowQuality();
     testRasterizationQuality();
     testCloudQuality();
+    testGodRays();
 }
 
diff --git a/src/render/opengl/OpenGLRenderer.cpp b/src/render/opengl/OpenGLRenderer.cpp
index 93a9b67..291e607 100644
--- a/src/render/opengl/OpenGLRenderer.cpp
+++ b/src/render/opengl/OpenGLRenderer.cpp
@@ -9,6 +9,7 @@
 #include "CloudsRenderer.h"
 #include "Scenery.h"
 #include "LightingManager.h"
+#include "GodRaysSampler.h"
 #include "Logs.h"
 #include "Vector3.h"
 
@@ -71,6 +72,7 @@ void OpenGLRenderer::initialize()
 
         getCloudsRenderer()->setEnabled(false);
         getLightingManager()->setSpecularity(false);
+        getGodRaysSampler()->setEnabled(false);
 
         skybox->initialize();
         skybox->updateScenery();
diff --git a/src/render/software/AtmosphereRenderer.cpp b/src/render/software/AtmosphereRenderer.cpp
index 15218b8..9ae2ff4 100644
--- a/src/render/software/AtmosphereRenderer.cpp
+++ b/src/render/software/AtmosphereRenderer.cpp
@@ -5,6 +5,7 @@
 #include "AtmosphereDefinition.h"
 #include "AtmosphereModelBruneton.h"
 #include "AtmosphereResult.h"
+#include "GodRaysSampler.h"
 #include "LightComponent.h"
 #include "LightStatus.h"
 #include "Scenery.h"
@@ -98,7 +99,7 @@ AtmosphereResult BaseAtmosphereRenderer::getSkyColor(Vector3)
     return result;
 }
 
-Vector3 BaseAtmosphereRenderer::getSunDirection(bool cache) const
+Vector3 BaseAtmosphereRenderer::getSunDirection(bool) const
 {
     AtmosphereDefinition* atmosphere = getDefinition();
     double sun_angle = (atmosphere->propDayTime()->getValue() + 0.75) * M_PI * 2.0;
@@ -131,7 +132,7 @@ AtmosphereResult SoftwareBrunetonAtmosphereRenderer::applyAerialPerspective(Vect
     AtmosphereDefinition* definition = getDefinition();
     AtmosphereResult result;
 
-    /* Get base perspective */
+    // Get base perspective
     switch (definition->model)
     {
     case AtmosphereDefinition::ATMOSPHERE_MODEL_BRUNETON:
@@ -141,7 +142,10 @@ AtmosphereResult SoftwareBrunetonAtmosphereRenderer::applyAerialPerspective(Vect
         ;
     }
 
-    /* Apply weather effects */
+    // Apply god rays ponderation
+    result.inscattering = parent->getGodRaysSampler()->apply(COLOR_BLACK, result.inscattering, location);
+
+    // Apply weather effects
     _applyWeatherEffects(definition, &result);
 
     return result;
@@ -162,10 +166,10 @@ AtmosphereResult SoftwareBrunetonAtmosphereRenderer::getSkyColor(Vector3 directi
 
     base = COLOR_BLACK;
 
-    /* Get night sky */
+    // Get night sky
     base = base.add(parent->getNightSky()->getColor(camera_location.y, direction));
 
-    /* Get sun shape */
+    // Get sun shape
     /*if (v3Dot(sun_direction, direction) >= 0)
     {
         double sun_radius = definition->sun_radius * SUN_RADIUS_SCALED * 5.0; // FIXME Why should we multiply by 5 ?
@@ -190,7 +194,7 @@ AtmosphereResult SoftwareBrunetonAtmosphereRenderer::getSkyColor(Vector3 directi
         }
     }*/
 
-    /* Get scattering */
+    // Get scattering
     AtmosphereResult result;
     Vector3 location = camera_location.add(direction.scale(6421.0));
     switch (definition->model)
@@ -202,7 +206,10 @@ AtmosphereResult SoftwareBrunetonAtmosphereRenderer::getSkyColor(Vector3 directi
         result = BaseAtmosphereRenderer::applyAerialPerspective(location, result.base);
     }
 
-    /* Apply weather effects */
+    // Apply god rays ponderation
+    result.inscattering = parent->getGodRaysSampler()->apply(COLOR_BLACK, result.inscattering, location);
+
+    // Apply weather effects
     _applyWeatherEffects(definition, &result);
 
     return result;
diff --git a/src/render/software/CloudBasicLayerRenderer.cpp b/src/render/software/CloudBasicLayerRenderer.cpp
index 22e7167..b966265 100644
--- a/src/render/software/CloudBasicLayerRenderer.cpp
+++ b/src/render/software/CloudBasicLayerRenderer.cpp
@@ -239,7 +239,7 @@ bool CloudBasicLayerRenderer::alterLight(BaseCloudsModel *model, LightComponent*
         }
     }
 
-    double miminum_light = 0.5;
+    double miminum_light = 0.3;
     factor = 1.0 - (1.0 - miminum_light) * factor;
 
     light->color.r *= factor;
diff --git a/src/render/software/CloudsRenderer.cpp b/src/render/software/CloudsRenderer.cpp
index db8c19e..d2a700f 100644
--- a/src/render/software/CloudsRenderer.cpp
+++ b/src/render/software/CloudsRenderer.cpp
@@ -198,3 +198,23 @@ bool CloudsRenderer::applyLightFilter(LightComponent &light, const Vector3 &at)
 
     return true;
 }
+
+double CloudsRenderer::getHighestAltitude()
+{
+    CloudsDefinition* definition = parent->getScenery()->getClouds();
+    double highest = 0.0;
+
+    int n = definition->count();
+    double low, high;
+    for (int i = 0; i < n; i++)
+    {
+        BaseCloudsModel* layer_model = getLayerModel(i);
+        layer_model->getAltitudeRange(&low, &high);
+        if (high > highest)
+        {
+            highest = high;
+        }
+    }
+
+    return highest;
+}
diff --git a/src/render/software/CloudsRenderer.h b/src/render/software/CloudsRenderer.h
index be1686a..acb28c1 100644
--- a/src/render/software/CloudsRenderer.h
+++ b/src/render/software/CloudsRenderer.h
@@ -67,6 +67,11 @@ public:
      * Return true if the light was altered.
      */
     virtual bool applyLightFilter(LightComponent &light, const Vector3 &at) override;
+
+    /**
+     * Get the highest altitude of all layers.
+     */
+    double getHighestAltitude();
 private:
     double quality;
 
diff --git a/src/render/software/GodRaysResult.cpp b/src/render/software/GodRaysResult.cpp
new file mode 100644
index 0000000..5a629ae
--- /dev/null
+++ b/src/render/software/GodRaysResult.cpp
@@ -0,0 +1,38 @@
+#include "GodRaysResult.h"
+
+GodRaysResult::GodRaysResult(double inside_length, double full_length):
+    inside_length(inside_length), full_length(full_length)
+{
+}
+
+Color GodRaysResult::apply(const Color &raw, const Color &atmosphered, const GodRaysParams &params)
+{
+    if (inside_length == 0.0)
+    {
+        return raw;
+    }
+    else if (inside_length < full_length)
+    {
+        double diff = full_length - inside_length;
+        double factor = 1.0 - params.penetration * diff;
+        double minimum = params.resistance;
+        double complement = 1.0 - minimum;
+        if (factor < minimum)
+        {
+            factor = minimum;
+        }
+        else
+        {
+            factor = pow((factor - minimum) / complement, params.boost) * complement + minimum;
+        }
+
+        return Color(raw.r + (atmosphered.r - raw.r) * factor,
+                     raw.g + (atmosphered.g - raw.g) * factor,
+                     raw.b + (atmosphered.b - raw.b) * factor,
+                     atmosphered.a);
+    }
+    else
+    {
+        return atmosphered;
+    }
+}
diff --git a/src/render/software/GodRaysResult.h b/src/render/software/GodRaysResult.h
new file mode 100644
index 0000000..15102f4
--- /dev/null
+++ b/src/render/software/GodRaysResult.h
@@ -0,0 +1,40 @@
+#ifndef GODRAYSRESULT_H
+#define GODRAYSRESULT_H
+
+#include "software_global.h"
+
+#include "Color.h"
+
+namespace paysages {
+namespace software {
+
+/**
+ * Result of god rays computation.
+ */
+class SOFTWARESHARED_EXPORT GodRaysResult
+{
+public:
+    typedef struct {
+        double penetration;
+        double resistance;
+        double boost;
+    } GodRaysParams;
+
+public:
+    GodRaysResult() = default;
+    GodRaysResult(double inside_length, double full_length);
+
+    /**
+     * Apply the result on a base color.
+     */
+    Color apply(const Color &raw, const Color &atmosphered, const GodRaysParams &params);
+
+private:
+    double inside_length;
+    double full_length;
+};
+
+}
+}
+
+#endif // GODRAYSRESULT_H
diff --git a/src/render/software/GodRaysSampler.cpp b/src/render/software/GodRaysSampler.cpp
new file mode 100644
index 0000000..39c6e67
--- /dev/null
+++ b/src/render/software/GodRaysSampler.cpp
@@ -0,0 +1,220 @@
+#include "GodRaysSampler.h"
+
+#include "GodRaysDefinition.h"
+#include "AtmosphereDefinition.h"
+#include "SoftwareRenderer.h"
+#include "Vector3.h"
+#include "SpaceSegment.h"
+#include "GodRaysResult.h"
+#include "LightingManager.h"
+#include "FloatNode.h"
+#include "LightStatus.h"
+#include "Scenery.h"
+#include "TerrainDefinition.h"
+#include "CloudsRenderer.h"
+#include "Interpolation.h"
+#include <cmath>
+
+GodRaysSampler::GodRaysSampler()
+{
+    enabled = true;
+    bounds = new SpaceSegment();
+    definition = new GodRaysDefinition(NULL);
+    camera_location = new Vector3(0, 0, 0);
+    lighting = NULL;
+    low_altitude = -1.0;
+    high_altitude = 1.0;
+    sampling_step = 1.0;
+    max_length = 1.0;
+    data = new double[1];
+    setQuality(0.5);
+}
+
+GodRaysSampler::~GodRaysSampler()
+{
+    delete definition;
+    delete bounds;
+    delete camera_location;
+    delete[] data;
+}
+
+void GodRaysSampler::prepare(SoftwareRenderer *renderer)
+{
+    setCameraLocation(renderer->getCameraLocation(VECTOR_ZERO));
+    setLighting(renderer->getLightingManager());
+    setAltitudes(renderer->getScenery()->getTerrain()->getHeightInfo().min_height, renderer->getCloudsRenderer()->getHighestAltitude());
+    renderer->getScenery()->getAtmosphere()->childGodRays()->copy(definition);
+    reset();
+}
+
+void GodRaysSampler::reset()
+{
+    *bounds = SpaceSegment(Vector3(camera_location->x - max_length, low_altitude, camera_location->z - max_length),
+                           Vector3(camera_location->x + max_length, high_altitude, camera_location->z + max_length));
+    samples_x = round(bounds->getXDiff() / sampling_step) + 1;
+    samples_y = round(bounds->getYDiff() / sampling_step) + 1;
+    samples_z = round(bounds->getZDiff() / sampling_step) + 1;
+
+    long n = samples_x * samples_y * samples_z;
+    delete[] data;
+    data = new double[n];
+    for (long i = 0; i < n; i++)
+    {
+        data[i] = -1.0;
+    }
+}
+
+void GodRaysSampler::setEnabled(bool enabled)
+{
+    this->enabled = enabled;
+}
+
+void GodRaysSampler::setLighting(LightingManager *manager)
+{
+    this->lighting = manager;
+}
+
+void GodRaysSampler::setQuality(double factor)
+{
+    setQuality(5.0 / (factor * 8.0 + 1.0), 100.0, 5.0 / (factor * 80.0 + 1.0));
+    reset();
+}
+
+void GodRaysSampler::setQuality(double sampling_step, double max_length, double walk_step)
+{
+    this->sampling_step = sampling_step;
+    this->max_length = max_length;
+    this->walk_step = walk_step;
+}
+
+void GodRaysSampler::setCameraLocation(const Vector3 &location)
+{
+    *camera_location = location;
+}
+
+void GodRaysSampler::setAltitudes(double low, double high)
+{
+    low_altitude = low;
+    high_altitude = high;
+}
+
+void GodRaysSampler::getSamples(int *x, int *y, int *z) const
+{
+    *x = samples_x;
+    *y = samples_y;
+    *z = samples_z;
+}
+
+Color GodRaysSampler::getRawLight(const Vector3 &location, bool filtered) const
+{
+    if (lighting)
+    {
+        LightStatus status(lighting, location, *camera_location, filtered);
+        lighting->fillStatus(status, location);
+        return status.getSum();
+    }
+    else
+    {
+        return COLOR_TRANSPARENT;
+    }
+}
+
+double GodRaysSampler::getCachedLight(const Vector3 &location)
+{
+    double x = location.x - bounds->getStart().x;
+    double y = location.y - bounds->getStart().y;
+    double z = location.z - bounds->getStart().z;
+
+    int ix = (int)floor(x / sampling_step);
+    int iy = (int)floor(y / sampling_step);
+    int iz = (int)floor(z / sampling_step);
+
+    // Check cache limits
+    if (ix < 0 || ix >= samples_x - 1 || iy < 0 || iy >= samples_y - 1 || iz < 0 || iz >= samples_z - 1)
+    {
+        return 1.0;
+    }
+
+    // Hit cache
+    double p[8] = {
+        getCache(ix, iy, iz),
+        getCache(ix + 1, iy, iz),
+        getCache(ix + 1, iy + 1, iz),
+        getCache(ix, iy + 1, iz),
+        getCache(ix, iy, iz + 1),
+        getCache(ix + 1, iy, iz + 1),
+        getCache(ix + 1, iy + 1, iz + 1),
+        getCache(ix, iy + 1, iz + 1)
+    };
+    return Interpolation::trilinear(p,
+                                    (x - sampling_step * double(ix)) / sampling_step,
+                                    (y - sampling_step * double(iy)) / sampling_step,
+                                    (z - sampling_step * double(iz)) / sampling_step);
+}
+
+GodRaysResult GodRaysSampler::getResult(const SpaceSegment &segment)
+{
+    Vector3 step = segment.getEnd().sub(segment.getStart());
+    double max_length = step.getNorm();
+    step = step.normalize().scale(walk_step);
+    Vector3 walker = segment.getStart();
+    double travelled = 0.0;
+    double inside = 0.0;
+
+    if (max_length > this->max_length)
+    {
+        max_length = this->max_length;
+    }
+
+    while (travelled < max_length)
+    {
+        double light = getCachedLight(walker);
+
+        inside += light * walk_step;
+
+        walker = walker.add(step);
+        travelled += walk_step;
+    }
+
+    return GodRaysResult(inside, travelled);
+}
+
+Color GodRaysSampler::apply(const Color &raw, const Color &atmosphered, const Vector3 &location)
+{
+    if (enabled)
+    {
+        GodRaysResult result = getResult(SpaceSegment(*camera_location, location));
+
+        GodRaysResult::GodRaysParams params;
+        params.penetration = definition->propPenetration()->getValue();
+        params.resistance = definition->propResistance()->getValue();
+        params.boost = definition->propBoost()->getValue();
+
+        return result.apply(raw, atmosphered, params);
+    }
+    else
+    {
+        return atmosphered;
+    }
+}
+
+inline double GodRaysSampler::getCache(int x, int y, int z)
+{
+    double *cache = data + z * samples_x * samples_y + y * samples_x + x;
+    if (*cache < 0.0)
+    {
+        Vector3 location = Vector3(bounds->getStart().x + sampling_step * (double)x,
+                                   bounds->getStart().y + sampling_step * (double)y,
+                                   bounds->getStart().z + sampling_step * (double)z);
+        double unfiltered_power = getRawLight(location, false).getPower();
+        if (unfiltered_power == 0.0)
+        {
+            *cache = 1.0;
+        }
+        else
+        {
+            *cache = getRawLight(location, true).getPower() / unfiltered_power;
+        }
+    }
+    return *cache;
+}
diff --git a/src/render/software/GodRaysSampler.h b/src/render/software/GodRaysSampler.h
new file mode 100644
index 0000000..27efc67
--- /dev/null
+++ b/src/render/software/GodRaysSampler.h
@@ -0,0 +1,124 @@
+#ifndef GODRAYSSAMPLER_H
+#define GODRAYSSAMPLER_H
+
+#include "software_global.h"
+
+namespace paysages {
+namespace software {
+
+/**
+ * 3D sampler for "god rays".
+ */
+class SOFTWARESHARED_EXPORT GodRaysSampler
+{
+public:
+    GodRaysSampler();
+    ~GodRaysSampler();
+
+    inline const SpaceSegment &getBounds() const {return *bounds;}
+    inline double getSamplingStep() const {return sampling_step;}
+    inline double getMaxLength() const {return max_length;}
+    inline double getWalkStep() const {return walk_step;}
+
+    /**
+     * Prepare the sampler from a renderer.
+     */
+    void prepare(SoftwareRenderer *renderer);
+
+    /**
+     * Reset the sampler cache.
+     *
+     * This needs to be called after all setXXX method have been called.
+     */
+    void reset();
+
+    /**
+     * Enable or disable the god rays effect.
+     */
+    void setEnabled(bool enabled);
+
+    /**
+     * Set the lighting manager to use for raw sampling.
+     */
+    void setLighting(LightingManager *manager);
+
+    /**
+     * Set the overall quality factor (0.0-1.0).
+     */
+    void setQuality(double factor);
+
+    /**
+     * Set the quality indicators.
+     */
+    void setQuality(double sampling_step, double max_length, double walk_step);
+
+    /**
+     * Set the camera location.
+     *
+     * This will fix the limits of sampling data, around the camera location.
+     */
+    void setCameraLocation(const Vector3 &location);
+
+    /**
+     * Set the altitude boundaries.
+     */
+    void setAltitudes(double low, double high);
+
+    /**
+     * Get the number of samples in each dimension.
+     */
+    void getSamples(int *x, int *y, int *z) const;
+
+    /**
+     * Get the raw light at a location (without using the cached sampling).
+     */
+    Color getRawLight(const Vector3 &location, bool filtered) const;
+
+    /**
+     * Get the lighting factor at a given point, using (and filling) the cached sampling.
+     */
+    double getCachedLight(const Vector3 &location);
+
+    /**
+     * Get the god rays effect on a space segment.
+     */
+    GodRaysResult getResult(const SpaceSegment &segment);
+
+    /**
+     * Apply the god rays effect to a location.
+     *
+     * *raw* is the shaded color, without atmospheric effects.
+     * *atmosphered* is the shaded color, with atmospheric effects applied.
+     */
+    Color apply(const Color &raw, const Color &atmosphered, const Vector3 &location);
+
+private:
+    double getCache(int x, int y, int z);
+
+private:
+    bool enabled;
+    SpaceSegment *bounds;
+
+    GodRaysDefinition *definition;
+
+    double sampling_step;
+    double max_length;
+    double walk_step;
+
+    int samples_x;
+    int samples_y;
+    int samples_z;
+
+    double low_altitude;
+    double high_altitude;
+    Vector3 *camera_location;
+
+    LightingManager *lighting;
+
+    double *data;
+};
+
+}
+}
+
+#endif // GODRAYSSAMPLER_H
diff --git a/src/render/software/LightComponent.cpp b/src/render/software/LightComponent.cpp
index bc21dca..ac00e66 100644
--- a/src/render/software/LightComponent.cpp
+++ b/src/render/software/LightComponent.cpp
@@ -1,5 +1,6 @@
 #include "LightComponent.h"
 
-/*LightComponent::LightComponent()
+LightComponent::LightComponent(const Color &color, const Vector3 &direction, double reflection, bool altered):
+    color(color), direction(direction), reflection(reflection), altered(altered)
 {
-}*/
+}
diff --git a/src/render/software/LightComponent.h b/src/render/software/LightComponent.h
index 1c18663..4a0140b 100644
--- a/src/render/software/LightComponent.h
+++ b/src/render/software/LightComponent.h
@@ -17,7 +17,8 @@ namespace software {
 class SOFTWARESHARED_EXPORT LightComponent
 {
 public:
-    //LightComponent();
+    LightComponent() = default;
+    LightComponent(const Color &color, const Vector3 &direction, double reflection = 0.0, bool altered = true);
 
     Color color;        // Light power
     Vector3 direction;  // Direction the light is travelling
diff --git a/src/render/software/LightStatus.cpp b/src/render/software/LightStatus.cpp
index 48373a5..31555d1 100644
--- a/src/render/software/LightStatus.cpp
+++ b/src/render/software/LightStatus.cpp
@@ -1,32 +1,41 @@
 #include "LightStatus.h"
 
 #include "LightingManager.h"
+#include "LightComponent.h"
 #include "Color.h"
 #include "SurfaceMaterial.h"
 
-LightStatus::LightStatus(LightingManager *manager, const Vector3 &location, const Vector3 &eye)
+LightStatus::LightStatus(LightingManager *manager, const Vector3 &location, const Vector3 &eye, bool filtered)
 {
     this->max_power = 0.0;
     this->manager = manager;
     this->location = location;
     this->eye = eye;
+    this->filtered = filtered;
 }
 
 void LightStatus::pushComponent(LightComponent component)
 {
-    double power = component.color.getPower();
-    if (component.altered && (power < max_power * 0.05 || power < 0.001))
+    if (filtered)
     {
-        // Exclude filtered lights that are owerpowered by a previous one
-        return;
-    }
-
-    if (manager->alterLight(component, location))
-    {
-        if (power > max_power)
+        double power = component.color.getPower();
+        if (component.altered && (power < max_power * 0.05 || power < 0.001))
         {
-            max_power = power;
+            // Exclude filtered lights that are owerpowered by a previous one
+            return;
         }
+
+        if (manager->alterLight(component, location))
+        {
+            if (power > max_power)
+            {
+                max_power = power;
+            }
+            components.push_back(component);
+        }
+    }
+    else
+    {
         components.push_back(component);
     }
 }
@@ -43,3 +52,15 @@ Color LightStatus::apply(const Vector3 &normal, const SurfaceMaterial &material)
     final.a = material.base->a;
     return final;
 }
+
+Color LightStatus::getSum() const
+{
+    Color final = COLOR_BLACK;
+
+    for (auto component: components)
+    {
+        final = final.add(component.color);
+    }
+
+    return final;
+}
diff --git a/src/render/software/LightStatus.h b/src/render/software/LightStatus.h
index 947ee8a..0f0d7c2 100644
--- a/src/render/software/LightStatus.h
+++ b/src/render/software/LightStatus.h
@@ -16,7 +16,7 @@ namespace software {
 class SOFTWARESHARED_EXPORT LightStatus
 {
 public:
-    LightStatus(LightingManager *manager, const Vector3 &location, const Vector3 &eye);
+    LightStatus(LightingManager *manager, const Vector3 &location, const Vector3 &eye, bool filtered=true);
 
     inline Vector3 getLocation() const {return location;}
 
@@ -24,11 +24,17 @@ public:
 
     Color apply(const Vector3 &normal, const SurfaceMaterial &material);
 
+    /**
+     * Return the sum of all received lights.
+     */
+    Color getSum() const;
+
 private:
     double max_power;
     LightingManager* manager;
     Vector3 location;
     Vector3 eye;
+    bool filtered;
     std::vector<LightComponent> components;
 };
 
diff --git a/src/render/software/LightingManager.cpp b/src/render/software/LightingManager.cpp
index e352489..bb0bb96 100644
--- a/src/render/software/LightingManager.cpp
+++ b/src/render/software/LightingManager.cpp
@@ -37,6 +37,11 @@ void LightingManager::addStaticLight(const LightComponent &light)
     static_lights.push_back(light);
 }
 
+void LightingManager::clearSources()
+{
+    sources.clear();
+}
+
 void LightingManager::registerSource(LightSource *source)
 {
     if (std::find(sources.begin(), sources.end(), source) == sources.end())
@@ -47,7 +52,15 @@ void LightingManager::registerSource(LightSource *source)
 
 void LightingManager::unregisterSource(LightSource *source)
 {
-    sources.erase(std::find(sources.begin(), sources.end(), source));
+    if (std::find(sources.begin(), sources.end(), source) != sources.end())
+    {
+        sources.erase(std::find(sources.begin(), sources.end(), source));
+    }
+}
+
+void LightingManager::clearFilters()
+{
+    filters.clear();
 }
 
 void LightingManager::registerFilter(LightFilter* filter)
@@ -60,7 +73,10 @@ void LightingManager::registerFilter(LightFilter* filter)
 
 void LightingManager::unregisterFilter(LightFilter *filter)
 {
-    filters.erase(std::find(filters.begin(), filters.end(), filter));
+    if (std::find(filters.begin(), filters.end(), filter) != filters.end())
+    {
+        filters.erase(std::find(filters.begin(), filters.end(), filter));
+    }
 }
 
 bool LightingManager::alterLight(LightComponent &component, const Vector3 &location)
@@ -168,10 +184,8 @@ Color LightingManager::applyFinalComponent(const LightComponent &component, cons
     return result;
 }
 
-Color LightingManager::apply(const Vector3 &eye, const Vector3 &location, const Vector3 &normal, const SurfaceMaterial &material)
+void LightingManager::fillStatus(LightStatus &status, const Vector3 &location) const
 {
-    LightStatus status(this, location, eye);
-
     for (auto &light: static_lights)
     {
         status.pushComponent(light);
@@ -187,6 +201,11 @@ Color LightingManager::apply(const Vector3 &eye, const Vector3 &location, const
             }
         }
     }
+}
 
+Color LightingManager::apply(const Vector3 &eye, const Vector3 &location, const Vector3 &normal, const SurfaceMaterial &material)
+{
+    LightStatus status(this, location, eye);
+    fillStatus(status, location);
     return status.apply(normal, material);
 }
diff --git a/src/render/software/LightingManager.h b/src/render/software/LightingManager.h
index 027d032..f4c2544 100644
--- a/src/render/software/LightingManager.h
+++ b/src/render/software/LightingManager.h
@@ -35,6 +35,11 @@ public:
      */
     void addStaticLight(const LightComponent &light);
 
+    /**
+     * Remove all registered sources.
+     */
+    void clearSources();
+
     /**
      * Register a source of dynamic lighting.
      */
@@ -45,6 +50,11 @@ public:
      */
     void unregisterSource(LightSource *source);
 
+    /**
+     * Remove all registered filters.
+     */
+    void clearFilters();
+
     /**
      * Register a filter that will receive all alterable lights.
      */
@@ -72,6 +82,11 @@ public:
      */
     Color applyFinalComponent(const LightComponent &component, const Vector3 &eye, const Vector3 &location, const Vector3 &normal, const SurfaceMaterial &material);
 
+    /**
+     * Compute the light status at a given location.
+     */
+    void fillStatus(LightStatus &status, const Vector3 &location) const;
+
     /**
      * Apply lighting to a surface at a given location.
      */
diff --git a/src/render/software/NightSky.cpp b/src/render/software/NightSky.cpp
index 6cb4bd9..d70923e 100644
--- a/src/render/software/NightSky.cpp
+++ b/src/render/software/NightSky.cpp
@@ -95,7 +95,7 @@ const Color NightSky::getColor(double altitude, const Vector3 &direction)
 
 }
 
-bool NightSky::getLightsAt(std::vector<LightComponent> &result, const Vector3 &location) const
+bool NightSky::getLightsAt(std::vector<LightComponent> &result, const Vector3 &) const
 {
     LightComponent moon, sky;
 
diff --git a/src/render/software/SkyRasterizer.cpp b/src/render/software/SkyRasterizer.cpp
index c2d207a..0386cb6 100644
--- a/src/render/software/SkyRasterizer.cpp
+++ b/src/render/software/SkyRasterizer.cpp
@@ -9,6 +9,7 @@
 #include "Rasterizer.h"
 #include "CanvasFragment.h"
 #include "RenderProgress.h"
+#include "GodRaysSampler.h"
 
 #define SPHERE_SIZE 20000.0
 
@@ -68,7 +69,7 @@ void SkyRasterizer::rasterizeToCanvas(CanvasPortion* canvas)
             direction.z = SPHERE_SIZE * sin(current_i) * cos(current_j + step_j);
             vertex4 = camera_location.add(direction);
 
-            /* TODO Triangles at poles */
+            // TODO Triangles at poles
             pushQuad(canvas, vertex1, vertex4, vertex3, vertex2);
         }
         progress->add(res_i);
@@ -84,7 +85,7 @@ Color SkyRasterizer::shadeFragment(const CanvasFragment &fragment) const
     camera_location = renderer->getCameraLocation(location);
     direction = location.sub(camera_location);
 
-    /* TODO Don't compute result->color if it's fully covered by clouds */
+    // TODO Don't compute sky color if it's fully covered by clouds
     result = renderer->getAtmosphereRenderer()->getSkyColor(direction.normalize()).final;
     result = renderer->getCloudsRenderer()->getColor(camera_location, camera_location.add(direction.scale(10.0)), result);
 
diff --git a/src/render/software/SoftwareRenderer.cpp b/src/render/software/SoftwareRenderer.cpp
index d8509cc..6289511 100644
--- a/src/render/software/SoftwareRenderer.cpp
+++ b/src/render/software/SoftwareRenderer.cpp
@@ -17,6 +17,8 @@
 #include "NightSky.h"
 #include "LightStatus.h"
 #include "LightingManager.h"
+#include "GodRaysSampler.h"
+#include "GodRaysResult.h"
 #include "System.h"
 #include "Thread.h"
 
@@ -37,6 +39,7 @@ SoftwareRenderer::SoftwareRenderer(Scenery* scenery):
 
     fluid_medium = new FluidMediumManager(this);
     lighting = new LightingManager();
+    godrays = new GodRaysSampler();
 
     lighting->registerFilter(water_renderer);
     lighting->registerFilter(terrain_renderer);
@@ -52,6 +55,7 @@ SoftwareRenderer::~SoftwareRenderer()
 
     delete fluid_medium;
     delete lighting;
+    delete godrays;
 
     delete nightsky_renderer;
 
@@ -88,6 +92,7 @@ void SoftwareRenderer::prepare()
     nightsky_renderer->update();
 
     // Prepare global tools
+    godrays->prepare(this);
     fluid_medium->clearMedia();
     //fluid_medium->registerMedium(water_renderer);
 }
@@ -96,6 +101,7 @@ void SoftwareRenderer::setQuality(double quality)
 {
     terrain_renderer->setQuality(quality);
     clouds_renderer->setQuality(quality);
+    godrays->setQuality(quality);
 
     // TEMP compat with old code
     render_quality = (int)(quality * 9.0) + 1;
diff --git a/src/render/software/SoftwareRenderer.h b/src/render/software/SoftwareRenderer.h
index 5ac5a4d..b8fe4ce 100644
--- a/src/render/software/SoftwareRenderer.h
+++ b/src/render/software/SoftwareRenderer.h
@@ -57,6 +57,7 @@ public:
 
     inline FluidMediumManager* getFluidMediumManager() const {return fluid_medium;}
     inline LightingManager* getLightingManager() const {return lighting;}
+    inline GodRaysSampler* getGodRaysSampler() const {return godrays;}
 
     virtual Color applyLightingToSurface(const Vector3 &location, const Vector3 &normal, const SurfaceMaterial &material);
     virtual Color applyMediumTraversal(Vector3 location, Color color);
@@ -67,6 +68,7 @@ private:
 
     FluidMediumManager* fluid_medium;
     LightingManager* lighting;
+    GodRaysSampler* godrays;
 
     BaseAtmosphereRenderer* atmosphere_renderer;
     CloudsRenderer* clouds_renderer;
diff --git a/src/render/software/software.pro b/src/render/software/software.pro
index 9198949..dc427d9 100644
--- a/src/render/software/software.pro
+++ b/src/render/software/software.pro
@@ -52,7 +52,9 @@ SOURCES += SoftwareRenderer.cpp \
     clouds/CloudModelCirrus.cpp \
     clouds/CloudModelCumuloNimbus.cpp \
     RenderProgress.cpp \
-    LightSource.cpp
+    LightSource.cpp \
+    GodRaysSampler.cpp \
+    GodRaysResult.cpp
 
 HEADERS += SoftwareRenderer.h\
         software_global.h \
@@ -94,7 +96,9 @@ HEADERS += SoftwareRenderer.h\
     clouds/CloudModelCirrus.h \
     clouds/CloudModelCumuloNimbus.h \
     RenderProgress.h \
-    LightSource.h
+    LightSource.h \
+    GodRaysSampler.h \
+    GodRaysResult.h
 
 unix:!symbian {
     maemo5 {
diff --git a/src/render/software/software_global.h b/src/render/software/software_global.h
index 79c82b1..f80e348 100644
--- a/src/render/software/software_global.h
+++ b/src/render/software/software_global.h
@@ -49,6 +49,9 @@ namespace software {
 
     class TerrainRayWalker;
 
+    class GodRaysSampler;
+    class GodRaysResult;
+
     class Canvas;
     class CanvasPortion;
     class CanvasPixel;
diff --git a/src/tests/GodRaysSampler_Test.cpp b/src/tests/GodRaysSampler_Test.cpp
new file mode 100644
index 0000000..f4a0c97
--- /dev/null
+++ b/src/tests/GodRaysSampler_Test.cpp
@@ -0,0 +1,149 @@
+#include "BaseTestCase.h"
+#include "GodRaysSampler.h"
+
+#include "SpaceSegment.h"
+#include "Vector3.h"
+#include "LightingManager.h"
+#include "LightSource.h"
+#include "LightFilter.h"
+#include "LightComponent.h"
+#include "Color.h"
+
+TEST(GodRaysSampler, getBounds)
+{
+    GodRaysSampler sampler;
+
+    sampler.setAltitudes(-5.0, 300.0);
+    sampler.setCameraLocation(Vector3(100.0, 0.0, 8000.0));
+    sampler.setQuality(10.0, 500.0, 1.0);
+    sampler.reset();
+
+    SpaceSegment bounds = sampler.getBounds();
+
+    EXPECT_VECTOR3_COORDS(bounds.getStart(), -400.0, -5.0, 7500.0);
+    EXPECT_VECTOR3_COORDS(bounds.getEnd(), 600.0, 300.0, 8500.0);
+}
+
+TEST(GodRaysSampler, getSamples)
+{
+    GodRaysSampler sampler;
+
+    sampler.setAltitudes(-50.0, 100.0);
+    sampler.setQuality(10.0, 100.0, 1.0);
+    sampler.reset();
+
+    int x, y, z;
+    sampler.getSamples(&x, &y, &z);
+
+    EXPECT_EQ(21, x);
+    EXPECT_EQ(16, y);
+    EXPECT_EQ(21, z);
+}
+
+TEST(GodRaysSampler, setQuality)
+{
+    GodRaysSampler sampler;
+
+    sampler.setQuality(0.0);
+    EXPECT_DOUBLE_EQ(5.0, sampler.getSamplingStep());
+    EXPECT_DOUBLE_EQ(100.0, sampler.getMaxLength());
+    EXPECT_DOUBLE_EQ(5.0, sampler.getWalkStep());
+
+    sampler.setQuality(0.5);
+    EXPECT_DOUBLE_EQ(1.0, sampler.getSamplingStep());
+    EXPECT_DOUBLE_EQ(100.0, sampler.getMaxLength());
+    EXPECT_DOUBLE_EQ(0.12195121951, sampler.getWalkStep());
+
+    sampler.setQuality(1.0);
+    EXPECT_DOUBLE_EQ(0.55555555555, sampler.getSamplingStep());
+    EXPECT_DOUBLE_EQ(100.0, sampler.getMaxLength());
+    EXPECT_DOUBLE_EQ(0.06172839506, sampler.getWalkStep());
+}
+
+class GodRayLightSource: public LightSource
+{
+    virtual bool getLightsAt(std::vector<LightComponent> &result, const Vector3 &location) const override
+    {
+        LightComponent light;
+        light.color = Color(fabs(location.x), fabs(location.y), fabs(location.z));
+        result.push_back(light);
+        return true;
+    }
+};
+
+TEST(GodRaysSampler, getRawLight)
+{
+    class TestLightFilter: public LightFilter
+    {
+        virtual bool applyLightFilter(LightComponent &light, const Vector3 &at) override
+        {
+            if (at.x > 0.5)
+            {
+                light.color.r = 0.1;
+                return true;
+            }
+            else
+            {
+                return true;
+            }
+        }
+    };
+
+    GodRayLightSource light_source;
+    TestLightFilter filter;
+    LightingManager lighting;
+    lighting.registerSource(&light_source);
+    lighting.registerFilter(&filter);
+
+    GodRaysSampler sampler;
+    sampler.setLighting(&lighting);
+
+    EXPECT_COLOR_RGBA(sampler.getRawLight(Vector3(0.0, 0.0, 0.0), false), 0.0, 0.0, 0.0, 1.0);
+    EXPECT_COLOR_RGBA(sampler.getRawLight(Vector3(1.0, 2.0, -6.0), false), 1.0, 2.0, 6.0, 1.0);
+
+    EXPECT_COLOR_RGBA(sampler.getRawLight(Vector3(0.0, 0.0, 0.0), true), 0.0, 0.0, 0.0, 1.0);
+    EXPECT_COLOR_RGBA(sampler.getRawLight(Vector3(1.0, 2.0, -6.0), true), 0.1, 2.0, 6.0, 1.0);
+}
+
+TEST(GodRaysSampler, getCachedLight)
+{
+    class TestLightFilter: public LightFilter
+    {
+        virtual bool applyLightFilter(LightComponent &, const Vector3 &at) override
+        {
+            return at.x <= 10.0 or at.x >= 50.0;
+        }
+    };
+
+    GodRayLightSource light_source;
+    TestLightFilter filter;
+    LightingManager lighting;
+    lighting.registerSource(&light_source);
+    lighting.registerFilter(&filter);
+
+    GodRaysSampler sampler;
+
+    sampler.setLighting(&lighting);
+    sampler.setQuality(5.0, 100.0, 1.0);
+    sampler.setAltitudes(-10.0, 10.0);
+    sampler.reset();
+
+    // outside the sampler, considered full light
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, 15.0, 0.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, -15.0, 0.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(-120.0, 0.0, 0.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(120.0, 0.0, 0.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, 0.0, -100.1)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, 0.0, 100.1)));
+
+    // at sampling point
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, 0.0, 0.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(0.0, 5.0, 10.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(5.0, 5.0, 10.0)));
+    EXPECT_DOUBLE_EQ(1.0, sampler.getCachedLight(Vector3(10.0, 5.0, 10.0)));
+    EXPECT_DOUBLE_EQ(0.0, sampler.getCachedLight(Vector3(15.0, 5.0, 10.0)));
+    EXPECT_DOUBLE_EQ(0.0, sampler.getCachedLight(Vector3(20.0, 5.0, 10.0)));
+
+    // in between sampling points
+    EXPECT_DOUBLE_EQ(0.5, sampler.getCachedLight(Vector3(12.5, 5.0, 10.0)));
+}
diff --git a/src/tests/Interpolation_Test.cpp b/src/tests/Interpolation_Test.cpp
new file mode 100644
index 0000000..000a771
--- /dev/null
+++ b/src/tests/Interpolation_Test.cpp
@@ -0,0 +1,27 @@
+#include "BaseTestCase.h"
+#include "Interpolation.h"
+
+TEST(Interpolation, trilinear)
+{
+    double p[8] = {0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0};
+
+    EXPECT_DOUBLE_EQ(0.0, Interpolation::trilinear(p, 0.0, 0.0, 0.0));
+    EXPECT_DOUBLE_EQ(1.0, Interpolation::trilinear(p, 1.0, 0.0, 0.0));
+    EXPECT_DOUBLE_EQ(2.0, Interpolation::trilinear(p, 1.0, 1.0, 0.0));
+    EXPECT_DOUBLE_EQ(3.0, Interpolation::trilinear(p, 0.0, 1.0, 0.0));
+    EXPECT_DOUBLE_EQ(4.0, Interpolation::trilinear(p, 0.0, 0.0, 1.0));
+    EXPECT_DOUBLE_EQ(5.0, Interpolation::trilinear(p, 1.0, 0.0, 1.0));
+    EXPECT_DOUBLE_EQ(6.0, Interpolation::trilinear(p, 1.0, 1.0, 1.0));
+    EXPECT_DOUBLE_EQ(7.0, Interpolation::trilinear(p, 0.0, 1.0, 1.0));
+
+    EXPECT_DOUBLE_EQ(0.5, Interpolation::trilinear(p, 0.5, 0.0, 0.0));
+    EXPECT_DOUBLE_EQ(1.5, Interpolation::trilinear(p, 0.0, 0.5, 0.0));
+    EXPECT_DOUBLE_EQ(2.0, Interpolation::trilinear(p, 0.0, 0.0, 0.5));
+
+    EXPECT_DOUBLE_EQ(1.5, Interpolation::trilinear(p, 0.5, 0.5, 0.0));
+    EXPECT_DOUBLE_EQ(3.5, Interpolation::trilinear(p, 0.0, 0.5, 0.5));
+    EXPECT_DOUBLE_EQ(2.5, Interpolation::trilinear(p, 0.5, 0.0, 0.5));
+
+    EXPECT_DOUBLE_EQ(3.5, Interpolation::trilinear(p, 0.5, 0.5, 0.5));
+}
+
diff --git a/src/tests/tests.pro b/src/tests/tests.pro
index 4c49dea..85b15ad 100644
--- a/src/tests/tests.pro
+++ b/src/tests/tests.pro
@@ -29,7 +29,9 @@ SOURCES += main.cpp \
     ColorHSL_Test.cpp \
     RenderProgress_Test.cpp \
     IntNode_Test.cpp \
-    LightingManager_Test.cpp
+    LightingManager_Test.cpp \
+    GodRaysSampler_Test.cpp \
+    Interpolation_Test.cpp
 
 HEADERS += \
     BaseTestCase.h