Programming With QuickTime VR

Link Hot Spot Atom

The link hot spot atom specifies information for hot spots of type kQTVRHotSpotLinkType ('link'). Its atom type is thus 'link'. The link hot spot atom contains specific information about a link hot spot.

The structure of a link hot spot atom is defined by the VRLinkHotSpotAtom data type:



 
typedef struct VRLinkHotSpotAtom {

    UInt16                              majorVersion;

    UInt16                              minorVersion;

    UInt32                              toNodeID;

    UInt32                              fromValidFlags;

    Float32                             fromPan;

    Float32                             fromTilt;

    Float32                             fromFOV;

    FloatPoint                          fromViewCenter;

    UInt32                              toValidFlags;

    Float32                             toPan;

    Float32                             toTilt;

    Float32                             toFOV;

    FloatPoint                          toViewCenter;

    Float32                             distance;

    UInt32                              flags;

    UInt32                              reserved1;

    UInt32                              reserved2;

} VRLinkHotSpotAtom, *VRLinkHotSpotAtomPtr;

majorVersion: The major version number of the file format.
minorVersion: The minor version number of the file format.
toNodeID: The ID of the destination node (that is, the node to which this hot spot is linked).
fromValidFlags: A set of flags that indicate which source node view settings are valid. See "Link Hot Spot Valid Flags" for a description of the available flags.
fromPan: The preferred from-pan angle at the source node (that is, the node containing the hot spot).
fromTilt: The preferred from-tilt angle at the source node.
fromFOV: The preferred from-field of view at the source node.
fromViewCenter: The preferred from-view center at the source node.
toValidFlags: A set of flags that indicate which destination node view settings are valid. See "Link Hot Spot Valid Flags" for a description of the available flags.
toPan: The pan angle to use when displaying the destination node.
toTilt: The tilt angle to use when displaying the destination node.
toFOV: The field of view to use when displaying the destination node.
toViewCenter: The view center to use when displaying the destination node.
distance: The distance between the source node and the destination node.
flags: A set of link hot spot flags. Currently, this field is unused and should be set to 0.
reserved1: Reserved. This field must be 0.
reserved2: Reserved. This field must be 0.

Certain fields in the link hot spot atom are not currently used by QuickTime VR. The fromValidFlags field is generally set to zero and the from fields are not used. However, these fields could be quite useful if you have created a transition movie from one node to another. The from angles can be used to swing the current view of the source node to align with the first frame of the transition movie. The distance field is intended for use with 3D applications, but is also not currently used by QuickTime VR.

Link Hot Spot Valid Flags

The toValidFlags field in the link hot spot atom structure specifies which view settings are to be used when moving to a destination node from a hot spot. You can use these bit flags to specify a value for that field:



 
enum {

    kQTVRValidPan                               = 1 << 0,

    kQTVRValidTilt                              = 1 << 1,

    kQTVRValidFOV                               = 1 << 2,

    kQTVRValidViewCenter                        = 1 << 3

};

Constant descriptions

kQTVRValidPan: If this bit is set, the destination pan angle is used.
kQTVRValidTilt: If this bit is set, the destination tilt angle is used.
kQTVRValidFOV: If this bit is set, the destination field of view is used.
kQTVRValidViewCenter: If this bit is set, the destination view center is used.