Bug 194727 Pyramid chart with 2d+ dimension should like a pyramid
Pyramid chart in 2d+ dimension should like a pyramid, rather than a triangle with depth effect. In addition, pyramid in 2d+ should like itself in 3d as well. Take a look at attached screenshot to compare the charts.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/BaseRenderer.java
pre.setDepth( -dSeriesThickness );
			}
			else
			
			{
				pre.setDepth( 0 );
			}
			if ( i == nSides )
			{
				fP = f;
			}
			else if ( i == iSmallestYIndex )
			{
				fP = fBrighter;
			}
			else
			{
				fP = fDarker;
			}
			pre.setBackground( fP );
			if ( bDeferred )
			{
				alModel.add( pre.copy( ) );
			}
			else
			{
				ipr.fillPolygon( pre );
			}
			if ( i == nSides )
			{