HLAPI -- Forces and Collision Detection

The section called HDAPI vs. HLAPI mentioned that the HL used openGl to render haptic feedback. The HL commands to capture the shapes are wrapped around existing openGL code.

Depth Buffer -- The HL reads the openGl depth buffer to calculate the geometry and render forces. "The depth buffer is used for hidden surface removal." [1]

Depth buffer shapes are less accurate than feedback buffer shapes although in nearly all
applications, the difference in accuracy is undetectable. [2]

Feedback Buffer -- "Capture geometric primitieves" Commands that generate points, lines and polygons. [1]

If you are rendering lines and points to be used as constraints, you must use a feedbackbuffer shape since depth buffer shapes cannot capture points and lines.[2]


[1] The OpenHaptics™ Toolkit: A Library for Adding 3D Touch™ Navigation and Haptics to Graphics Applications
Brandon Itkowitz* Josh Handley† Weihang Zhu
[2] OHTK Programmer's Guide 7-12 page 62/118