Perspective 2-point and 3-point grids
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Inkscape |
Triaged
|
Wishlist
|
Unassigned |
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.
Changed in inkscape: | |
importance: | Undecided → Wishlist |
Changed in inkscape: | |
status: | New → Triaged |
tags: | added: grids |
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