protected override GeometryBuffer CreateGeometryBuffer()
{
var gb = new GeometryBuffer();
gb.Declarations.Add(new VertexElement(VertexAttribute.Position, VertexDataType.Float, 3));
gb.Declarations.Add(new VertexElement(VertexAttribute.TexCoord0, VertexDataType.Float, 2));
gb.Declarations.Add(new VertexElement(VertexAttribute.Color, VertexDataType.Byte, 4));
gb.Declarations.Add(new VertexElement(VertexAttribute.Normal, VertexDataType.Float, 1));
gb.Declarations.CalculateStrides();
return gb;
}