Programming with QuickTime VR

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QTVRSetBackBufferPrefs

You can use the QTVRSetBackBufferPrefs function to set the resolution, pixel format, and size of the back buffer maintained internally by QuickTime VR for caching a panoramic image in a particular pixel format.

OSErr QTVRSetBackBufferPrefs (
                     QTVRInstance qtvr,
                     UInt16 resolution,
                     UInt32 cachePixelFormat,
                     SInt16 cacheSize);
qtvr
An instance of a QuickTime VR movie.
resolution
The desired image resolution.
cachePixelFormat
The desired pixel format for the back buffer. This value should be one of the defined pixel formats . See "Pixel Formats" for more information.
cacheSize
The desired size for the panorama back buffer. See "Cache Sizes" for constants you can use to specify a cache size.
function result
A result code.

DESCRIPTION

The QTVRSetBackBufferPrefs function sets the resolution, pixel format, and size of the panorama back buffer for the movie specified by the qtvr parameter to the values specified by the resolution , cachePixelFormat , and cacheSize parameters. You can specify a resolution that isn't contained in the movie file; if you do so, QuickTime VR takes the highest resolution image in the file and reduces it to fit into the specified buffer size.

If you specify an unsupported pixel format, the QTVRSetBackBufferPrefs function may return an error. See "Pixel Formats" for more information.

SPECIAL CONSIDERATIONS

QTVRSetBackBufferPrefs is valid only for panoramic nodes.

SEE ALSO

Use QTVRGetAvailableResolutions [link] to determine which resolutions are supported by a node. Use QTVRGetBackBufferMemInfo [link] to determine the memory requirements for the preferred settings.

© 1997 Apple Computer, Inc.

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