Perspective 2-point and 3-point grids

[Tavmjong]

The next logical step after the addition of the
axonometric grid is to add perspective grids. Here is a
proposal for how such grids should behave along with
some perl code that generates prototype grids.

As a temporary measure, the perl code could be used as
a start for encoding an effect that generates a
perspective grid. Snapping to the grid could be done by
turning on snapping to objects.

Perspective Grid:

  A 2 or 3 vanishing point perspective grid is defined
by four points:

    Left vanishing point.
    Right vanishing point.
    Eye (corner) point.
    Scale point.

    The vanishing points determine a horizon line. The
eye point and
    scale point are on a line perpendicular to the
horizon line. The
    eye point is the one closest to the horizon line.

    If the eye point is on the horizon line, a 2 Point
perspective
    grid is drawn. Otherwise a 3 Point perspective grid
is drawn.

    The grid is calculated assuming that the eye point
is above the
    drawing plane such that the angle between any two
lines connecting
    two vanishing points with the eye point are orthogonal.

  Adjustment:

    Each of the four input points are connected to
draggable handles.

    Shift-dragging a vanishing point handle rotates the
vanishing
    points around the eye point. The angles are
displayed in the
    notification region. This simulates rotating the
grid around the
    corner point.

    Ctrl-dragging restricts rotations to multiples of
the rotations
    step angle.

    Alt-dragging a vanishing point handle or scale
point restricts
    movement along the line connecting that point to
the eye point.

    Alt-dragging the eye point restricts movement along
a line
    connecting the eye point to the vanishing point or
scale point in
    the nearest direction of the drag.

  Option:

    Allow two grids to be viewable at the same time.
This allows one
    grid to be used to position second grid.

Attached files:

Perspective.svg: Sample grids with labeled handles.
blank.svg: Template file for use with perl scripts.
p2.prl: Perl script to generate 2 vanishing point grid.
p3.prl: Perl script to generate 3 vanishing point grid.

The perl files must be edited to change grid parameters.

[Tavmjong (tavmjong)]

Other attachments

[Tavmjong (tavmjong)]

Other attachments

[Tavmjong (tavmjong)]

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[Horkana-users (horkana-users)]

The detailed description should be good for any developers
interested in tackling this.
Screenshots of this from other applications might help.

See also

[ 1005753 ] Perspective grid
http://sourceforge.net/tracker/index.php?func=detail&aid=1005753&group_id=93438&atid=604309

[Tom Davidson (tjd-mit)]

Now that there are

[Tom Davidson (tjd-mit)]

Maybe this could be implemented using the new angled guidelines code?

[prkos (prkos)]

Does Objects to Guides on 3D box solve this, or maybe it comes close?

[KarlStiler (khruskowski)]

I'd love to have a perspective grid at hand. But i think a Grid on a Box would not really help, since it's used for measurement it should enable me to measure the "room". Coral Painter has such a perspective grid, in case you need an example. (http://www.pixelalley.com/p11/perspective_grid_property_bar.jpg)

Thanks.

Karl

[Antonio Roberts (hellocatfood)]

I'd like to see this implemented at some point.

prkos, the object to guide on a 3d box does give guides, but not in a grid format, which is what I think the OP is afterh

[su_v (suv-lp)]

Duplicate of Bug #170361 “Perspective grid”?

[Jody Collinge (jodycollinge)]

That would be great! Thanks for working on this.
Jody

On Mon, Jan 24, 2011 at 3:30 PM, ~suv <email address hidden> wrote:

> Duplicate of Bug #170361 “Perspective grid”?
>
> --
> You received this bug notification because you are a direct subscriber
> of the bug.
> https://bugs.launchpad.net/bugs/171586
>
> Title:
> Perspective 2-point and 3-point grids
>
> Status in Inkscape: A Vector Drawing Tool:
> Triaged
>
> Bug description:
> The next logical step after the addition of the
> axonometric grid is to add perspective grids. Here is a
> proposal for how such grids should behave along with
> some perl code that generates prototype grids.
>
> As a temporary measure, the perl code could be used as
> a start for encoding an effect that generates a
> perspective grid. Snapping to the grid could be done by
> turning on snapping to objects.
>
> Perspective Grid:
>
> A 2 or 3 vanishing point perspective grid is defined
> by four points:
>
> Left vanishing point.
> Right vanishing point.
> Eye (corner) point.
> Scale point.
>
> The vanishing points determine a horizon line. The
> eye point and
> scale point are on a line perpendicular to the
> horizon line. The
> eye point is the one closest to the horizon line.
>
> If the eye point is on the horizon line, a 2 Point
> perspective
> grid is drawn. Otherwise a 3 Point perspective grid
> is drawn.
>
> The grid is calculated assuming that the eye point
> is above the
> drawing plane such that the angle between any two
> lines connecting
> two vanishing points with the eye point are orthogonal.
>
> Adjustment:
>
> Each of the four input points are connected to
> draggable handles.
>
> Shift-dragging a vanishing point handle rotates the
> vanishing
> points around the eye point. The angles are
> displayed in the
> notification region. This simulates rotating the
> grid around the
> corner point.
>
> Ctrl-dragging restricts rotations to multiples of
> the rotations
> step angle.
>
> Alt-dragging a vanishing point handle or scale
> point restricts
> movement along the line connecting that point to
> the eye point.
>
> Alt-dragging the eye point restricts movement along
> a line
> connecting the eye point to the vanishing point or
> scale point in
> the nearest direction of the drag.
>
> Option:
>
> Allow two grids to be viewable at the same time.
> This allows one
> grid to be used to position second grid.
>
> Attached files:
>
> Perspective.svg: Sample grids with labeled handles.
> blank.svg: Template file for use with perl scripts.
> p2.prl: Perl script to generate 2 vanishing point grid.
> p3.prl: Perl script to generate 3 vanishing point grid.
>
> The perl files must be edited to change grid parameters.
>
> To unsubscribe from this bug, go to:
> https://bugs.launchpad.net/inkscape/+bug/171586/+subscribe
>