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492 17. Programming Input and Force Feedback
Figure 17.1. Using the proxy method for haptic rendering.
The HLAPI follows the OpenGL syntax and state machine model. It
allows the shapes of haptic surfaces to be described by points, lines and trian-
gular polygons, as well as sets material properties such as stiffness and friction.
It offers the possibility of taking advantage of the feedback, depth rendering
and the simultaneous 3D presentation which OpenGL offers. Indeed, there is
such a close connection between being able to see something and touch some-
thing that the analogy with OpenGL could open the door to a much wider
application of