Merge pull request #327 from thecelloman/smoothslope

Add a new Terrain brush action:  Smooth Slope.

Engine/source/gui/worldEditor/terrainActions.cpp

@@ -631,6 +631,52 @@ void SmoothHeightAction::process(Selection * sel, const Gui3DMouseEvent &, bool
    }
 }
 
+void SmoothSlopeAction::process(Selection * sel, const Gui3DMouseEvent &, bool selChanged, Type)  
+{  
+   if(!sel->size())  
+      return;  
+  
+   if(selChanged)  
+   {  
+      // Perform simple 2d linear regression on x&z and y&z:  
+      // b = (Avg(xz) - Avg(x)Avg(z))/(Avg(x^2) - Avg(x)^2)  
+      Point2F prod(0.f, 0.f);   // mean of product for covar  
+      Point2F avgSqr(0.f, 0.f); // mean sqr of x, y for var  
+      Point2F avgPos(0.f, 0.f);  
+      F32 avgHeight = 0.f;  
+      F32 z;  
+      Point2F pos;  
+      for(U32 k = 0; k < sel->size(); k++)  
+      {  
+         mTerrainEditor->getUndoSel()->add((*sel)[k]);  
+         pos = Point2F((*sel)[k].mGridPoint.gridPos.x, (*sel)[k].mGridPoint.gridPos.y);  
+         z = (*sel)[k].mHeight;  
+  
+         prod += pos * z;  
+         avgSqr += pos * pos;  
+         avgPos += pos;  
+         avgHeight += z;  
+      }  
+  
+      prod /= sel->size();  
+      avgSqr /= sel->size();  
+      avgPos /= sel->size();  
+      avgHeight /= sel->size();  
+  
+      Point2F avgSlope = (prod - avgPos*avgHeight)/(avgSqr - avgPos*avgPos);  
+  
+      F32 goalHeight;  
+      for(U32 i = 0; i < sel->size(); i++)  
+      {  
+         goalHeight = avgHeight + ((*sel)[i].mGridPoint.gridPos.x - avgPos.x)*avgSlope.x +  
+            ((*sel)[i].mGridPoint.gridPos.y - avgPos.y)*avgSlope.y;  
+         (*sel)[i].mHeight += (goalHeight - (*sel)[i].mHeight) * (*sel)[i].mWeight;  
+         mTerrainEditor->setGridInfo((*sel)[i]);  
+      }  
+      mTerrainEditor->scheduleGridUpdate();  
+   }  
+}  
+
 void PaintNoiseAction::process(Selection * sel, const Gui3DMouseEvent &, bool selChanged, Type type)
 {
    // If this is the ending

Engine/source/gui/worldEditor/terrainActions.h

@@ -258,6 +258,15 @@ class SmoothHeightAction : public TerrainAction
       void process(Selection * sel, const Gui3DMouseEvent & event, bool selChanged, Type type);
 };
 
+class SmoothSlopeAction : public TerrainAction  
+{  
+   public:  
+      SmoothSlopeAction(TerrainEditor * editor) : TerrainAction(editor){}  
+      StringTableEntry getName(){return("smoothSlope");}  
+  
+      void process(Selection * sel, const Gui3DMouseEvent & event, bool selChanged, Type type);  
+};  
+
 class PaintNoiseAction : public TerrainAction
 {
    public:

Engine/source/gui/worldEditor/terrainEditor.cpp

@@ -710,6 +710,7 @@ TerrainEditor::TerrainEditor() :
    mActions.push_back(new AdjustHeightAction(this));
    mActions.push_back(new FlattenHeightAction(this));
    mActions.push_back(new SmoothHeightAction(this));
+   mActions.push_back(new SmoothSlopeAction(this));
    mActions.push_back(new PaintNoiseAction(this));
    //mActions.push_back(new ThermalErosionAction(this));