Add ability to 'look through camera'

[bentoogood]

Currently users can only view the 3d scene through the generic perspective camera.

They should be able to pick the camera to view the scene through from any camera existing in the scene.

Implementation details:

• Should the selection of the camera be from a dropdown list in the Viewer somewhere?
• Or could users drag a camera from the SceneHierarchy into the Viewer?
• What about lights?
• Users will want to be able to modify the position of a camera interactively whilst looking through it. What impact does this have?

[johnhaddon]

Sticking this in a milestone, because we need it for the Jabuka preview panel.

[johnhaddon]

My initial plan for this one is as follows :

• Add a camera on/off button and a camera path field in to the toolbar. The button will be off by default and the path field will be empty by default. In this state the behaviour will be as it is now.
• When the button is turned on, the viewer will look through the current render camera (defined by the StandardOptions node) by default. Choosing an alternative camera in the toolbar path field will look through that instead. In this mode the camera will not be moveable via the viewport interaction - in the future when we can determine the node that made it then perhaps we'll allow it to be moveable, but not in this iteration.
• Turning the button off will keep the view framed as-is, but reenable the camera interaction.

Does that seem OK?

[andrewkaufman]

Yeah, sounds good. What happens when you tick the button on, but there is no current render camera? Is that even possible or is there always a StandardOptions defining a camera?

[johnhaddon]

It is possible to have no current camera specified - in which case when doing an actual render you'd get a default camera at the origin. We could either lock to that default location in the viewer or do nothing in that scenario - do you have a preference as to which?

[andrewkaufman]

I'd vote lock I guess. If toggle-on still allowed movement in some cases, people might think they're able to move the real cameras that way, and that's a bit too interactive, isn't it.

[johnhaddon]

Cool - sounds good to me. I'm assuming we're also going to want resolution gates and wotnot, but I'll ask again about that once I get to it and once I've figured things out a bit more...