diff --git a/src/editing/terrain/paintingbrush.cpp b/src/editing/terrain/paintingbrush.cpp
index 8f18651..c24c396 100644
--- a/src/editing/terrain/paintingbrush.cpp
+++ b/src/editing/terrain/paintingbrush.cpp
@@ -123,7 +123,7 @@ void PaintingBrush::applyToTerrain(TerrainDefinition* terrain, double x, double
     case PAINTING_BRUSH_SMOOTH:
         if (reverse)
         {
-            terrainBrushSmooth(terrain->height_map, &brush, brush_strength);
+            terrainBrushSmooth(terrain->height_map, &brush, brush_strength * 30.0);
         }
         else
         {
@@ -133,15 +133,15 @@ void PaintingBrush::applyToTerrain(TerrainDefinition* terrain, double x, double
     case PAINTING_BRUSH_FLATTEN:
         if (reverse)
         {
-            _height = terrainGetInterpolatedHeight(terrain, x, z, 1);
+            _height = terrainGetInterpolatedHeight(terrain, x * terrain->scaling, z * terrain->scaling, 0, 1);
         }
         else
         {
-            terrainBrushFlatten(terrain->height_map, &brush, _height, brush_strength);
+            terrainBrushFlatten(terrain->height_map, &brush, _height, brush_strength * 30.0);
         }
         break;
     case PAINTING_BRUSH_RESTORE:
-        terrainBrushReset(terrain->height_map, &brush, brush_strength);
+        terrainBrushReset(terrain->height_map, &brush, brush_strength * 30.0);
         break;
     default:
         return;
diff --git a/src/editing/terrain/widgetheightmap.cpp b/src/editing/terrain/widgetheightmap.cpp
index f6cde1e..299d7b4 100644
--- a/src/editing/terrain/widgetheightmap.cpp
+++ b/src/editing/terrain/widgetheightmap.cpp
@@ -29,7 +29,7 @@ QGLWidget(parent)
     _wireframe = true;
     WaterDefinition* water_definition = (WaterDefinition*)WaterDefinitionClass.create();
     sceneryGetWater(water_definition);
-    _water_height = _renderer->terrain->getWaterHeight(_renderer);
+    _water_height = 0.0;
     WaterDefinitionClass.destroy(water_definition);
 
     _average_frame_time = 0.0;
@@ -74,7 +74,7 @@ void WidgetHeightMap::setTerrain(TerrainDefinition* terrain)
 {
     _terrain = terrain;
     TerrainRendererClass.bind(_renderer, _terrain);
-    _water_height = _renderer->terrain->getWaterHeight(_renderer);
+    _water_height = _renderer->terrain->getWaterHeight(_renderer) / _terrain->scaling;
 
     revert();
 }
@@ -210,7 +210,7 @@ void WidgetHeightMap::timerEvent(QTimerEvent*)
     _last_time = new_time;
 
     // Update top camera
-    Vector3 target = {_target_x, terrainGetInterpolatedHeight(_terrain, _target_x, _target_z, 1), _target_z};
+    Vector3 target = {_target_x, terrainGetInterpolatedHeight(_terrain, _target_x, _target_z, 1, 1), _target_z};
     cameraSetLocationCoords(_top_camera, target.x, target.y + 1.0, target.z + 0.1);
     cameraSetTarget(_top_camera, target);
     cameraSetZoomToTarget(_top_camera, _zoom);
@@ -531,7 +531,7 @@ void WidgetHeightMap::updateVertexInfo()
             vertex->point.x = (double) dx;
             vertex->point.z = (double) dz;
 
-            vertex->point.y = terrainGetGridHeight(_terrain, dx, dz, 1);
+            vertex->point.y = terrainGetGridHeight(_terrain, dx, dz, 1) * _terrain->height;
 
             vertex->painted = terrainIsPainted(_terrain->height_map, dx, dz);
         }
diff --git a/src/rendering/noise.c b/src/rendering/noise.c
index 60b652f..0baa57e 100644
--- a/src/rendering/noise.c
+++ b/src/rendering/noise.c
@@ -229,6 +229,13 @@ void noiseSetFunction(NoiseGenerator* generator, NoiseFunction* function)
     noiseValidate(generator);
 }
 
+void noiseSetCustomFunction(NoiseGenerator* generator, double (*func1d)(double x), double (*func2d)(double x, double y), double (*func3d)(double x, double y, double z))
+{
+    generator->_func_noise_1d = func1d;
+    generator->_func_noise_2d = func2d;
+    generator->_func_noise_3d = func3d;
+}
+
 void noiseSetFunctionParams(NoiseGenerator* generator, NoiseFunctionAlgorithm algorithm, double ridge_factor, double curve_factor)
 {
     NoiseFunction function = {algorithm, ridge_factor, curve_factor};
diff --git a/src/rendering/noise.h b/src/rendering/noise.h
index 5a30114..a8dea1a 100644
--- a/src/rendering/noise.h
+++ b/src/rendering/noise.h
@@ -46,6 +46,7 @@ void noiseCopy(NoiseGenerator* source, NoiseGenerator* destination);
 void noiseValidate(NoiseGenerator* generator);
 void noiseRandomizeOffsets(NoiseGenerator* generator);
 NoiseFunction noiseGetFunction(NoiseGenerator* generator);
+void noiseSetCustomFunction(NoiseGenerator* generator, double (*func1d)(double x), double (*func2d)(double x, double y), double (*func3d)(double x, double y, double z));
 void noiseSetFunction(NoiseGenerator* generator, NoiseFunction* function);
 void noiseSetFunctionParams(NoiseGenerator* generator, NoiseFunctionAlgorithm algorithm, double ridge_factor, double curve_factor);
 void noiseForceValue(NoiseGenerator* generator, double value);
diff --git a/src/rendering/terrain/public.h b/src/rendering/terrain/public.h
index 905e626..dddf26f 100644
--- a/src/rendering/terrain/public.h
+++ b/src/rendering/terrain/public.h
@@ -64,7 +64,7 @@ extern StandardRenderer TerrainRendererClass;
 void terrainAutoPreset(TerrainDefinition* definition, TerrainPreset preset);
 void terrainRenderSurface(Renderer* renderer);
 double terrainGetGridHeight(TerrainDefinition* definition, int x, int z, int with_painting);
-double terrainGetInterpolatedHeight(TerrainDefinition* definition, double x, double z, int with_painting);
+double terrainGetInterpolatedHeight(TerrainDefinition* definition, double x, double z, int scaled, int with_painting);
 size_t terrainGetMemoryStats(TerrainDefinition* definition);
 
 Renderer* terrainCreatePreviewRenderer();
diff --git a/src/rendering/terrain/ter_definition.c b/src/rendering/terrain/ter_definition.c
index be387c2..d61ef46 100644
--- a/src/rendering/terrain/ter_definition.c
+++ b/src/rendering/terrain/ter_definition.c
@@ -105,10 +105,10 @@ double terrainGetGridHeight(TerrainDefinition* definition, int x, int z, int wit
         height = noiseGet2DTotal(definition->_height_noise, (double)x, (double)z);
     }
 
-    return height * definition->height * definition->scaling;
+    return height;
 }
 
-double terrainGetInterpolatedHeight(TerrainDefinition* definition, double x, double z, int with_painting)
+double terrainGetInterpolatedHeight(TerrainDefinition* definition, double x, double z, int scaled, int with_painting)
 {
     double height;
     x /= definition->scaling;
@@ -119,5 +119,12 @@ double terrainGetInterpolatedHeight(TerrainDefinition* definition, double x, dou
         height = noiseGet2DTotal(definition->_height_noise, x, z);
     }
 
-    return height * definition->height * definition->scaling;
+    if (scaled)
+    {
+        return height * definition->height * definition->scaling;
+    }
+    else
+    {
+        return height;
+    }
 }
diff --git a/src/rendering/terrain/ter_painting.c b/src/rendering/terrain/ter_painting.c
index b94ab59..cefe248 100644
--- a/src/rendering/terrain/ter_painting.c
+++ b/src/rendering/terrain/ter_painting.c
@@ -307,12 +307,12 @@ static double* _getDataPointer(HeightMapData* data, int x, int z, HeightMapData*
             }
             else if (terrain)
             {
-                *pixel = terrainGetGridHeight(terrain, x, z, 0) / (terrain->height * terrain->scaling);
+                *pixel = terrainGetGridHeight(terrain, x, z, 0);
             }
         }
         else if (terrain)
         {
-            *pixel = terrainGetGridHeight(terrain, x, z, 0) / (terrain->height * terrain->scaling);
+            *pixel = terrainGetGridHeight(terrain, x, z, 0);
         }
     }
     return pixel;
@@ -411,7 +411,7 @@ int terrainHeightmapGetInterpolatedHeight(TerrainHeightMap* heightmap, double x,
             {
                 if (!terrainHeightmapGetGridHeight(heightmap, ix, iz, &value))
                 {
-                    value = terrainGetGridHeight(heightmap->terrain, ix, iz, 0) / (heightmap->terrain->scaling * heightmap->terrain->height);
+                    value = terrainGetGridHeight(heightmap->terrain, ix, iz, 0);
                 }
                 stencil[(iz - (zlow - 1)) * 4 + ix - (xlow - 1)] = value;
             }
@@ -468,7 +468,7 @@ static inline void _applyBrush(TerrainHeightMap* heightmap, TerrainBrush* brush,
     int x, z;
     double dx, dz, distance, influence;
 
-    force /= (heightmap->terrain->height * heightmap->terrain->scaling);
+    force /= heightmap->terrain->height;
 
     for (x = brush_rect.xstart; x <= brush_rect.xend; x++)
     {
@@ -536,10 +536,10 @@ static double _applyBrushSmooth(TerrainHeightMap* heightmap, TerrainBrush* brush
     UNUSED(data);
 
     double ideal, factor;
-    ideal = terrainGetInterpolatedHeight(heightmap->terrain, x + brush->total_radius * 0.5, z, 1);
-    ideal += terrainGetInterpolatedHeight(heightmap->terrain, x - brush->total_radius * 0.5, z, 1);
-    ideal += terrainGetInterpolatedHeight(heightmap->terrain, x, z - brush->total_radius * 0.5, 1);
-    ideal += terrainGetInterpolatedHeight(heightmap->terrain, x, z + brush->total_radius * 0.5, 1);
+    ideal = terrainGetInterpolatedHeight(heightmap->terrain, (x + brush->total_radius * 0.5) * heightmap->terrain->scaling, z * heightmap->terrain->scaling, 0, 1);
+    ideal += terrainGetInterpolatedHeight(heightmap->terrain, (x - brush->total_radius * 0.5) * heightmap->terrain->scaling, z * heightmap->terrain->scaling, 0, 1);
+    ideal += terrainGetInterpolatedHeight(heightmap->terrain, x * heightmap->terrain->scaling, (z - brush->total_radius * 0.5) * heightmap->terrain->scaling, 0, 1);
+    ideal += terrainGetInterpolatedHeight(heightmap->terrain, x * heightmap->terrain->scaling, (z + brush->total_radius * 0.5) * heightmap->terrain->scaling, 0, 1);
     ideal /= 4.0;
     factor = influence * force;
     if (factor > 1.0)
@@ -571,7 +571,7 @@ static double _applyBrushReset(TerrainHeightMap* heightmap, TerrainBrush* brush,
     UNUSED(brush);
     UNUSED(data);
 
-    double ideal = terrainGetInterpolatedHeight(heightmap->terrain, x, z, 0);
+    double ideal = terrainGetInterpolatedHeight(heightmap->terrain, x * heightmap->terrain->scaling, z * heightmap->terrain->scaling, 0, 0);
     return basevalue + (ideal - basevalue) * influence * force;
 }
 
diff --git a/src/rendering/terrain/ter_render.c b/src/rendering/terrain/ter_render.c
index c6d15a0..0a1e72e 100644
--- a/src/rendering/terrain/ter_render.c
+++ b/src/rendering/terrain/ter_render.c
@@ -18,7 +18,7 @@ static double _fakeGetHeight(Renderer* renderer, double x, double z, int with_pa
 
 static double _realGetHeight(Renderer* renderer, double x, double z, int with_painting)
 {
-    return terrainGetInterpolatedHeight(renderer->terrain->definition, x, z, with_painting);
+    return terrainGetInterpolatedHeight(renderer->terrain->definition, x, z, 1, with_painting);
 }
 
 static TerrainResult _fakeGetResult(Renderer* renderer, double x, double z, int with_painting, int with_textures)
diff --git a/src/testing/main.c b/src/testing/main.c
index df8b459..e220580 100644
--- a/src/testing/main.c
+++ b/src/testing/main.c
@@ -10,6 +10,7 @@ extern void test_camera_case(Suite* s);
 extern void test_clouds_case(Suite* s);
 extern void test_render_case(Suite* s);
 extern void test_noise_case(Suite* s);
+extern void test_terrain_painting_case(Suite* s);
 
 int main(int argc, char** argv)
 {
@@ -26,6 +27,7 @@ int main(int argc, char** argv)
     test_clouds_case(s);
     test_render_case(s);
     test_noise_case(s);
+    test_terrain_painting_case(s);
 
     SRunner *sr = srunner_create(s);
     srunner_run_all(sr, CK_NORMAL);
diff --git a/src/testing/test_terrain_painting.c b/src/testing/test_terrain_painting.c
new file mode 100644
index 0000000..23cbcb7
--- /dev/null
+++ b/src/testing/test_terrain_painting.c
@@ -0,0 +1,237 @@
+#include "testing/common.h"
+
+#include <math.h>
+#include "rendering/tools.h"
+#include "rendering/terrain/public.h"
+
+/* Noise sin period is defined at 20.0 */
+#define X_FACTOR (M_PI / 10.0)
+
+static double _noise1dMock(double x)
+{
+    return sin(x * X_FACTOR) * 0.5 + 0.5;
+}
+
+static double _noise2dMock(double x, double y)
+{
+    UNUSED(y);
+    return sin(x * X_FACTOR) * 0.5 + 0.5;
+}
+
+static double _noise3dMock(double x, double y, double z)
+{
+    UNUSED(y);
+    UNUSED(z);
+    return sin(x * X_FACTOR) * 0.5 + 0.5;
+}
+
+static TerrainDefinition* _setUpDefinition()
+{
+    TerrainDefinition* terrain = (TerrainDefinition*)TerrainDefinitionClass.create();
+    terrain->height = 3.0;
+    terrain->scaling = 1.0;
+    noiseClearLevels(terrain->_height_noise);
+    NoiseLevel level = {1.0, 2.0, -1.0, 0.0, 0.0, 0.0};
+    noiseAddLevel(terrain->_height_noise, level, 0);
+    noiseSetCustomFunction(terrain->_height_noise, _noise1dMock, _noise2dMock, _noise3dMock);
+    return terrain;
+}
+
+static void _tearDownDefinition(TerrainDefinition* terrain)
+{
+    TerrainDefinitionClass.destroy(terrain);
+}
+
+START_TEST(test_terrain_painting_grid)
+{
+    /* Set up */
+    TerrainDefinition* terrain = _setUpDefinition();
+
+    /* Test base grid */
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 0, 0, 0), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 0, 1, 0), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 0, 0, 1), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 1, 0, 0), sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 2, 0, 0), sin(2.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 3, 0, 0), sin(3.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 4, 0, 0), sin(4.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 5, 0, 0), 1.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 6, 0, 0), sin(4.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -1, 0, 0), -sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 10, 0, 0), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 15, 0, 0), -1.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 20, 0, 0), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -5, 0, 0), -1.0);
+
+    /* Test interpolated result */
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 0.0, 0.0, 0, 0), 0.0);
+    ck_assert_double_in_range(terrainGetInterpolatedHeight(terrain, 0.5, 0.0, 0, 0), 0.1564, 0.1566);
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 1.0, 0.0, 0, 0), sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 0.0, 0.0, 1, 0), 0.0);
+    ck_assert_double_in_range(terrainGetInterpolatedHeight(terrain, 0.5, 0.0, 1, 0), 3.0 * 0.1564, 3.0 * 0.1566);
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 1.0, 0.0, 1, 0), 3.0 * sin(1.0 * X_FACTOR));
+
+    /* Test scaling */
+    terrain->scaling = 2.0;
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 0, 0, 0), 0.0);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 1, 0, 0), sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 2, 0, 0), sin(2.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 3, 0, 0), sin(3.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 0, 0, 0, 0), 0.0);
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 1, 0, 0, 0), sin(0.5 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 2, 0, 0, 0), sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 3, 0, 0, 0), sin(1.5 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 0, 0, 1, 0), 0.0);
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 1, 0, 1, 0), 6.0 * sin(0.5 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 2, 0, 1, 0), 6.0 * sin(1.0 * X_FACTOR));
+    ck_assert_double_eq(terrainGetInterpolatedHeight(terrain, 3, 0, 1, 0), 6.0 * sin(1.5 * X_FACTOR));
+
+    /* Tear down */
+    _tearDownDefinition(terrain);
+}
+END_TEST
+
+static void _checkBrushResultSides(TerrainDefinition* terrain, TerrainBrush* brush, double center, double midhard, double hard, double midsoft, double soft, double exter, double neg_midhard, double neg_hard, double neg_midsoft, double neg_soft, double neg_exter)
+{
+    UNUSED(brush);
+
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 0, 0, 1), center);
+
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 1, 0, 1), midhard);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 2, 0, 1), hard);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 3, 0, 1), midsoft);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 4, 0, 1), soft);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, 5, 0, 1), exter);
+
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -1, 0, 1), neg_midhard);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -2, 0, 1), neg_hard);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -3, 0, 1), neg_midsoft);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -4, 0, 1), neg_soft);
+    ck_assert_double_eq(terrainGetGridHeight(terrain, -5, 0, 1), neg_exter);
+}
+
+static void _checkBrushResult(TerrainDefinition* terrain, TerrainBrush* brush, double center, double midhard, double hard, double midsoft, double soft, double exter, int mirror)
+{
+    if (mirror)
+    {
+        _checkBrushResultSides(terrain, brush, center, midhard, hard, midsoft, soft, exter, -midhard, -hard, -midsoft, -soft, -exter);
+    }
+    else
+    {
+        _checkBrushResultSides(terrain, brush, center, midhard, hard, midsoft, soft, exter, midhard, hard, midsoft, soft, exter);
+    }
+}
+
+START_TEST(test_terrain_painting_brush_flatten)
+{
+    /* Set up */
+    TerrainDefinition* terrain = _setUpDefinition();
+    TerrainBrush brush = {0.0, 0.0, 2.0, 2.0, 4.0};
+    terrain->height = 1.0;
+    terrain->scaling = 1.0;
+    noiseForceValue(terrain->_height_noise, 0.0);
+
+    /* Test flattening center at 0.5 */
+    _checkBrushResult(terrain, &brush, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush, 0.5, 1.0);
+    _checkBrushResult(terrain, &brush, 0.5, 0.5, 0.5, 0.25, 0.0, 0.0, 0);
+
+    /* Test brush strength */
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush, 0.5, 0.01);
+    _checkBrushResult(terrain, &brush, 0.005, 0.005, 0.005, 0.0025, 0.0, 0.0, 0);
+
+    /* Test cumulative effect */
+    terrainBrushFlatten(terrain->height_map, &brush, 0.5, 0.01);
+    _checkBrushResult(terrain, &brush, 0.00995, 0.00995, 0.00995, 0.0049875, 0.0, 0.0, 0);
+
+    /* Test with height modifier */
+    terrain->height = 10.0;
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush, 0.5, 1.0);
+    _checkBrushResult(terrain, &brush, 0.05, 0.05, 0.05, 0.025, 0.0, 0.0, 0);
+
+    /* Test with scaling modifier */
+    terrain->height = 10.0;
+    terrain->scaling = 2.0;
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush, 0.5, 1.0);
+    _checkBrushResult(terrain, &brush, 0.05, 0.05, 0.05, 0.025, 0.0, 0.0, 0);
+
+    /* Tear down */
+    _tearDownDefinition(terrain);
+}
+END_TEST
+
+START_TEST(test_terrain_painting_brush_reset)
+{
+    /* Set up */
+    TerrainDefinition* terrain = _setUpDefinition();
+    TerrainBrush brush = {0.0, 0.0, 2.0, 2.0, 4.0};
+    TerrainBrush brush_full = {0.0, 0.0, 4.0, 0.0, 4.0};
+    terrain->height = 1.0;
+    terrain->scaling = 1.0;
+    noiseForceValue(terrain->_height_noise, 1.0);
+
+    /* Test resetting at center */
+    _checkBrushResult(terrain, &brush, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush_full, 2.0, 1.0);
+    _checkBrushResult(terrain, &brush, 2.0, 2.0, 2.0, 2.0, 2.0, 1.0, 0);
+    terrainBrushReset(terrain->height_map, &brush, 1.0);
+    _checkBrushResult(terrain, &brush, 1.0, 1.0, 1.0, 1.5, 2.0, 1.0, 0);
+
+    /* Test brush strength */
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush_full, 2.0, 1.0);
+    _checkBrushResult(terrain, &brush, 2.0, 2.0, 2.0, 2.0, 2.0, 1.0, 0);
+    terrainBrushReset(terrain->height_map, &brush, 0.1);
+    _checkBrushResult(terrain, &brush, 1.9, 1.9, 1.9, 1.95, 2.0, 1.0, 0);
+
+    /* Test cumulative effect */
+    terrainBrushReset(terrain->height_map, &brush, 0.1);
+    _checkBrushResult(terrain, &brush, 1.81, 1.81, 1.81, 1.9025, 2.0, 1.0, 0);
+
+    /* Test with height modifier */
+    terrain->height = 10.0;
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush_full, 2.0, 1.0);
+    _checkBrushResult(terrain, &brush, 1.1, 1.1, 1.1, 1.1, 1.1, 1.0, 0);
+    terrainBrushReset(terrain->height_map, &brush, 0.1);
+    _checkBrushResult(terrain, &brush, 1.099, 1.099, 1.099, 1.0995, 1.1, 1.0, 0);
+
+    /* Test with scaling modifier */
+    terrain->height = 10.0;
+    terrain->scaling = 2.0;
+    terrainClearPainting(terrain->height_map);
+    _checkBrushResult(terrain, &brush, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 0);
+    terrainBrushFlatten(terrain->height_map, &brush_full, 2.0, 1.0);
+    _checkBrushResult(terrain, &brush, 1.1, 1.1, 1.1, 1.1, 1.1, 1.0, 0);
+    terrainBrushReset(terrain->height_map, &brush, 0.1);
+    _checkBrushResult(terrain, &brush, 1.099, 1.099, 1.099, 1.0995, 1.1, 1.0, 0);
+
+    /* Tear down */
+    _tearDownDefinition(terrain);
+
+    /* Test with scaling and the sinusoid setup (to test the basevalue sampling) */
+    terrain = _setUpDefinition();
+    terrain->height = 1.0;
+    terrain->scaling = 2.0;
+    _checkBrushResult(terrain, &brush, 0.0, 0.309016994375, 0.587785252292, 0.809016994375, 0.951056516295, 1.0, 1);
+    terrainBrushFlatten(terrain->height_map, &brush_full, 2.0, 1.0);
+    _checkBrushResultSides(terrain, &brush, 2.0, 2.0, 2.0, 2.0, 2.0, 1.0, 2.0, 2.0, 2.0, 2.0, -1.0);
+    terrainBrushReset(terrain->height_map, &brush, 1.0);
+    _checkBrushResultSides(terrain, &brush, 0.0, 0.309016994375, 0.587785252292, 2.0 - (2.0 - 0.809016994375) * 0.5, 2.0, 1.0, -0.309016994375, -0.587785252292, 2.0 - (2.0 + 0.809016994375) * 0.5, 2.0, -1.0);
+    _tearDownDefinition(terrain);
+}
+END_TEST
+
+TEST_CASE(terrain_painting,
+          test_terrain_painting_grid,
+          test_terrain_painting_brush_flatten,
+          test_terrain_painting_brush_reset)
+