BillboardItem3D

Detailed Description

Sometimes it is desirable to have objects which always face toward the camera. For example, a quad with text on it may always face the camera so as to be readable at all times.

While this can be achieved with a QGraphicsLookAtTransform on a normal Item3D, the BillboardItem3D class provides a more efficient "cheat" which takes advantage of the underlying 3D mathematics.

To use a BillboardItem3D declare it exactly like a regular Item3D. When the item is drawn a QGraphicsBillboardTransform will be applied to the item after all other transforms have been performed.

For example:

 Viewport {
     BillboardItem3D {
         mesh: Mesh { source: "model.obj" }
         effect: Effect {
             blending: true
             texture: "texture.png"
         }
     }
 }

For a practical illustration of its use see the forest example.