protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // Set the vertex buffer on the GraphicsDevice
            GraphicsDevice.SetVertexBuffer(vertexBuffer);
            
            //Set object and camera info
            effect.World = worldRotation * worldTranslation * worldRotation;
            effect.View = camera.view;
            effect.Projection = camera.projection;
            effect.Texture = texture;//这里设置贴图对象，可是如果有多张贴图呢怎么办
            //efect对象只有一个呀 难道这个从设备获取的对象可以定义多个吗
            effect.TextureEnabled = true;
            
            // Begin effect and draw for each pass
            foreach (EffectPass pass in effect.CurrentTechnique.Passes)
            {
               pass.Apply();
                GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>
                    (PrimitiveType.TriangleStrip, verts, 0, 2);
            }
            base.Draw(gameTime);
        }