Added osg::Grid shape class, and added an example of its use into the

hang glide demo.

src/osg/Shape.cpp

@@ -1,5 +1,43 @@
 #include <osg/Shape>
+#include <algorithm>
+
+using namespace osg;
+
+Grid::Grid()
+{
+}
+
+Grid::Grid(const Grid& mesh,const CopyOp& copyop): 
+    HeightField(mesh,copyop)
+{
+    _heights = mesh._heights;
+}
+
+Grid::~Grid()
+{
+}
 
 
+void Grid::allocGrid(unsigned int numColumns,unsigned int numRows, float value)
+{
+    if (_columns!=numColumns || _rows!=numRows)
+    {
+    	_heights.resize(numColumns*numRows);
+    }
+    _columns=numColumns;
+    _rows=numRows;
+    //_heights.fill(value);
+}
 
-
+void Grid::populateGrid(float minValue,float maxValue)
+{
+    float offset=minValue;
+    float gain=(maxValue-minValue)/(float)RAND_MAX;
+    for(unsigned int row=0;row<_rows;++row)
+    {
+    	for(unsigned int col=0;col<_columns;++col)
+	{
+	    setHeight(col,row,rand()*gain+offset);
+	}
+    }
+}