This sample illustrates how to generate and modify vrGeometry objects on the fly. In the sample the new geometry is used to render a custom particle system modeled after a fireworks display. Note that the particle positions and sizes are updated every fr a me through a subscriber. The application defines the class myApp, which is derived from vsApp, and overrides the vsApp::onKeyInput() method to allow for the keyboard input specified below. The sample allows the user to fly around the town database and renders a simple reticle overlay at the center of the screen. -This sample illustrates how to generate and modify vrGeometry objects on the fly. In the sample the new geometry is used to render a custom particle system modeled after a fireworks display. Note that the particle positions and sizes are updated every fr a me through a subscriber. The application defines the class myApp, which is derived from vsApp, and overrides the vsApp:: onKeyInput () method to allow for the keyboard input specified below. The sample allows the user to fly around the town database and renders a simple reticle overlay at the center of the screen.