[Bf-committers] Border zoom patch

Ben Stabler ben at half-dome.net
Fri Oct 27 18:11:39 CEST 2006

```Hi,

Campbell Barton wrote:
> are you discussing boarder zoom in perspective mode?

Zoom to cursor, actually, but the two have a similar basis.

> - of course theres no right answer to this one but this may be a good
> solution.
>
> create a plane (tri) that faces  the view and lies on the center point
> (that point you orbit around)
> then use the midpoint of the rectangle as a a ray, intersect it with the
> plane previously defined and use that intersection as your new center
> point-

This is effectively what is done at the moment. The function first pans to
the center of the drawn box (so, from the rotational center it pans, keeping
the focal point on the plane defined by the rotational center), and then it
zooms to fit the border (zooming towards the new focal point, which is on
the same plane as the previous focal point).

> after then you can modify the zoom value to make it work more
> like the user may expect- a small rect may zoom in further. - or you may
> find you dont need to adjust that. just moving the camera may be enough.

The problem is when the user wants to zoom past the plane; i.e. They see on
the screen an object, however it is beyond the focal point, so however far
in they try to zoom they are stopped by the fact that the focal point is on
their side of the object. From the user's perspective, the ideal behaviour
is for the focal point to move to meet the object, however this is
technically difficult; for example if there is a semi transparent plane
between the camera and the object; should the camera zoom to the plane? Or
another object behind it?

The alternative is instead of zooming to actually move the focal point along
the normal (a bit like fly mode on the camera), but then, do we hardcode a
value? Use a value calculated by distance from the origin? (this would cause
problems e.g. working on a city, and trying to zoom in on some detail far
from the origin)

Ben

Ben Stabler wrote:
> When you zoom in, you zoom towards a point in 3D space (the point you
rotate
> about when you hold MMB). You cant zoom past that point, or else it
wouldn't
> be zooming...
>
> Because the screen is 2D, it's possible to pan that point across the plane
> parallel to the screen, but to move it along the normal the function would
>
> Ben
>
> -----Original Message-----
> From: bf-committers-bounces at projects.blender.org
> [mailto:bf-committers-bounces at projects.blender.org] On Behalf Of trip
> somewhere
> Sent: 27 October 2006 16:23
> To: bf-blender developers
> Subject: Re: Re: [Bf-committers] Border zoom patch
>
> Alright dolly then, call it what you will the limit is rather
> annoying. What is it for ?
>
>
> On 10/27/06, Martin Poirier <theeth at yahoo.com> wrote:
>
>> --- trip somewhere <trip0o at gmail.com> wrote:
>>
>>
>>> New bug on it. The 3d cursor still has that annoying
>>> space limit to
>>> it's postion, could that be removed ?
>>> Example, if the cursor is not near it's target or
>>> even close after it
>>> starts to reach it's limit the zoom in will slow
>>> down to a complete
>>> stop preventing the requested zoom to amount.
>>>
>>> A rife old feature that should just go away
>>>
>> That's a misconception on your part. Zoom is on one
>> point in space, so that limitation is logical. What
>> you want is Dolly, not Zoom.
>>
>> Martin
>>
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--
Campbell J Barton

133 Hope Street
Geelong West, Victoria 3218 Australia

URL:    http://www.metavr.com
e-mail: cbarton at metavr.com
phone: AU (03) 5229 0241

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