Better smoothing for terrain editor!

So I came up with a little improvement to the terrain editor's smooth tool. Instead of just moving everything towards the average height, it takes a linear regression of the included terrain and moves the ground toward it. This lets you make smooth slopes, and is helpful for fixing small mistakes made with the other terrain editor tools.

To add:
In terrainActions.h around line 243 add

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);
};

In terrainActions.cpp around line 614 add

//------------------------------------------------------------------------------

void SmoothSlopeAction::process(Selection * sel, const Gui3DMouseEvent &, bool selChanged, Type)
{
   if(!sel->size())
      return;

   if(selChanged)
   {
      //perform simple 2d lin reg 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();
   }
}

In terrainEditor.cpp at line 695 add

mActions.push_back(new SmoothSlopeAction(this));

In terrFile.h change line 254 to

return U16(val * 32.0 + 0.5f);

This fixes an error that causes the terrain height to be rounded down.

In TerrainEditPallete.ed.gui at line 103 add

new GuiBitmapButtonCtrl() {
      canSaveDynamicFields = "0";
      internalName = "smoothSlope";
      Enabled = "1";
      isContainer = "0";
      Profile = "GuiButtonProfile";
      HorizSizing = "right";
      VertSizing = "bottom";
      position = "144 0";
      Extent = "25 19";
      MinExtent = "8 2";
      canSave = "1";
      Visible = "1";
      Command = "ETerrainEditor.switchAction( smoothSlope );";
      tooltipprofile = "GuiToolTipProfile";
      ToolTip = "Smooth Slope (5)";
      hovertime = "750";
      text = "Button";
      buttonType = "RadioButton";
      useMouseEvents = "0";
      bitmap = "tools/worldEditor/images/softCurve";
   };

Compile and enjoy!