Re: [clutter] 2.5D?

On Wed, 2007-11-14 at 12:17 +0000, Matthew Allum wrote:
> Hi;
>
> On Wed, 2007-11-14 at 12:55 +0100, Murray Cumming wrote:
> > Clutter is a 2.5D canvas, right? I mean, it can contain 2D objects that
> > can have some extruded depth, and which can move in 3D space. But it
> > can't have, for instance, a pyramid object?
>
> Yes and no. Everything is in 3D space but the API is heavily slanted
> towards more 2D usage (kind of 2D with 3D effects). Actors are
> essentially 2D quads but positionable / rotate-able in 3D space.
>
> You could however make an actor that was a pyramid (by dropping into raw
> GL). It would however be a bit cludgy with current API in wider scope
> (but potentially could be extended if the need is there).
>
> >
> > Maybe I'm even wrong about the extruded depth. Does
> > clutter_actor_set_depth() set the z position of the object or the z
> > dimension of the object?
>
> Z position. Maybe we should rename this and actually make depth a kind
> of volume like prop (or drop it). Would that seem more logical ?

I think so yes. It should at least be made clearer in the API
documentation for that function.

Is there any actual way to set an extruded depth then, or do actors now
have zero depth? For instance, can I ever see anything on screen if I
rotate a rectangle so only its edge is facing me?

> I've
> been a bit concerned about doing this in the past as having a set_z
> could kind of make people think Clutter really is a general 3D engine
> kind of thing.

That also just needs to be stated clearly, I think. For the uninitiated
it's not immediately clear that that's what all these iPhoneish UIs have
in common.

> > Is this a limitation of OpenGL ES, or just a design decision for
> > Clutter?
> >
>
> Design decision. If you start really heavily supporting 3D its really
> difficult to keep things simple as well as Im not heavily convinced that
> full full 3D really buys you much UI wise beyond crazed 1980's
> neuromancer style things

I tend to agree. I just didn't see this strategy from the start.

> Hope that helps in explaining things;

Thanks.

-- 
murrayc@murrayc.com
www.murrayc.com
www.openismus.com
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