NVIDIA Corporation
Frame Synchronization User’s Guide
– Version 3.0
25
C
HAPTER
3
Using the OpenGL Extensions
This call should be made before changing frame sync parameters in order to avoid
synchronization problems.
• To query the state of a display, call
wglIsEnabledGenlockI3D()
Configuring the Sync Trigger
The start of each frame
1
is synchronized to the sync trigger pulse. This pulse can be based
on the vertical retrace signal of the frame lock device configured as the Master device, or it
can be derived from an external video signal, like a house sync signal. Configuring the
trigger pulse involves:
• Selecting the sync source signal
• Deriving the trigger pulse from the sync source based on the sync source edge,
sampling frequency, and an optional delay
Select the Sync Source
• To select the source signal upon which to base the trigger pulse, call
wglGenlockSourceI3D()
and specify either the internal sync signal or an external sync signal.
• To query the sync source, call
wglGetGenlockSourceI3D()
Configure the Trigger Pulse
The trigger pulse is derived from the sync source, and is the signal to which all frame-lock
enabled boards are synchronized. Specify the trigger pulse as follows:
• Set An Edge Mode
Set the sync pulse to coincide with the leading edge, the falling edge, or both the
leading and falling edge of the source sync signal, by calling
wglGenlockSourceEdgeI3D()
and specifying either the rising edge, the falling edge, or both edges.
To query the edge mode, call
wglGetGenlockSourceEdgeI3D().
• Set a Sampling Value
Set the sync pulse as a function of samplings of the source signal, by calling
wglGenlockSampleRateI3D()
1. The current hardware does not support triggering on field data, so you cannot specify triggering on left-
only or right-only frames.
