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# Nonstandard cubes

An atom you add to the pano sample atom container to specify cubes other than six square faces.

## Overview

> Important: VR Media is deprecated in the QuickTime file format. The information that follows documents existing content containing VR Media and should not be used for new development.

Although the default representation for a cubic panorama is that of six square faces of a cube, it is possible to depart from this standard representation. When doing so, a new atom must be added to the pano sample atom container. The atom type is `'cufa'`. The atom is an array of data structures of type `QTVRCubicFaceData`. Each entry in the array describes one face of whatever polyhedron is being defined. `QTVRCubicFaceData` is defined as follows:

```c
struct QTVRCubicFaceData {
    float   orientation[4];
    float   center[2];
    float   aspect;
    float   skew;
};
typedef struct QTVRCubicFaceData    QTVRCubicFaceData;
```

The mathematical explanation of these data structures is beyond the scope of this content. The following table shows what values QuickTime VR uses for the default representation of six square sides.

|Orien- tation|Orien- tation|Orien- tation|Orien- tation|Center|Center|Aspect|Skew|Side    |
|-------------|-------------|-------------|-------------|------|------|------|----|--------|
|`1`          |`0`          |`0`          |`0`          |`0`   |`0`   |`1`   |`0` |# front |
|`-.5`        |`0`          |`.5`         |`0`          |`0`   |`0`   |`1`   |`0` |# right |
|`0`          |`0`          |`1`          |`0`          |`0`   |`0`   |`1`   |`0` |# back  |
|`.5`         |`0`          |`.5`         |`0`          |`0`   |`0`   |`1`   |`0` |# left  |
|`.5`         |`.5`         |`0`          |`0`          |`0`   |`0`   |`1`   |`0` |# top   |
|`-.5`        |`.5`         |`0`          |`0`          |`0`   |`0`   |`1`   |`0` |# bottom|

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