4:34 p.m.
I've got an hour or two at the end of this work to get started on my
CAD tools for Inkscape. (I checked out a couple of books on C++ from
my local library in case I get stuck on something.) :]
First let me ask a question, and then I'll explain my plan. (You guys
can let me know if the plan is feasible with Inkscape's architecture.)
Where can I find the classes used to represent Inkscape's geometries?
(I'm assuming that each geometry type is represented by a separate
class file. Let me know if this is incorrect.)
I've dowloaded the source code for Inkscape 0.44, but I couldn't find
a "geometry" folder in the "src" folder of the distribution. I
imagine
there would be a class file for rectangles, circles, elipses, lines,
polylines and polygons. (Unless rectangles are represented as
polylines and elipses as modified circles...)
Now, for my plan of attack...
Here is a basic description of my goal for the CAD tools:
Tools that allow the user to create the basic Inkscape geometries
using precise coordinate entry. (For example, the user could enter
coordinates into a dialog box for the two endpoints of a line and then
create that line, or they might enter the coordinate for the start
point of the line, and then an angle and distance that would be used
to compute the endpoint of the line.) Or the user might use other
tools to select the precise coodinates of existing geometries as the
input for such a tool, instead of entering the coordinates directly.
(For example, selecting the coordinate at the midpoint of a line and
the node of a polygon, and drawing the line with these exact
coordinates as the two endpoints.) These tools will also allow the
user to precisely modify existing geometries. (For example, move a
polygon by precisely selecting two coorinates on existing geometries
to compute the change in X and change in Y for the translation.)
Here is what I need to do:
[1] Design and implement what I call "coordinate selectors". These are
tools that allow very precise selection of points on the canvas.
Typically these points will be selected from existing geometries.I
would like to implement the following coordinate selectors for
Inkscape:
End Point (The coordinate at the end point of a line or polyline.)
Mid Point (The coordinate at the mid point of a line, polyline
segment, or polygon segment.)
Nearest Node (The coordinate at the node nearest to center of
selection window created by a mouse drag on the canvas.)
All Nodes (The coordinates of all nodes within a selection window
created by a mouse drag on the canvas.)
Perpendicular (The coordinate at point on a line, polyline segment,
polygon segment, or projection of any of these segments that is
perpendicular to another selected point.)
Intersection (The coordinate of the point at the intersection of two
or more lines, polyline segments, or polygon segments.)
Offset (The coordinate of a point created by projecting an offset
along the alignment or direction of two other points and a fixed
distance.)
Projected Intersection (The coordinate of a point located at the
projected intersection of any two lines, polyline segments, or polygon
segments.)
I'll get started by examing the geometry classes, which I will need to
use in my calculations for the coordinate tools. But I will also need
to figure out how to add a tool to Inkscapes user interface that
allows the user to drag a window on the canvas and then
programatically access the geometries or shapes that are contained by
or intersect that window. (Perhaps I can use the exisitng
pointer/selection tool in Inkscape?)
Let me know what you think of this plan, and let me know how I can get
to those geometry classes.
Scott Huey
P.S. - I can program the coordinate selectors in a way that allows
them to be used by other developer's tools, not just the ones I
design. For example, in OpenJUMP I am building coordinate selectors
that can store there selected coordinates on a "Coordinate Clipboard"
that can be accessed by the user or programatically.
9:03 p.m.
On 8/31/06, Redefined Horizons <redefined.horizons@...400...> wrote:
[1] Design and implement what I call "coordinate
selectors". These are
tools that allow very precise selection of points on the canvas.
Typically these points will be selected from existing geometries.I
would like to implement the following coordinate selectors for
Inkscape:
About six months ago, I had to learn a CAD system (TurboCAD) for the
first time. Since my only experience with vector editing was in
Inkscape, I had a difficult time with the transition. The trouble is
that the two programs have different work-styles. In Inkscape, the
basic approach is to draw a shape in the rough position you are
interested in, then refine it until it looks correct. CAD systems, on
the other hand, require users to draw shapes perfectly the first time,
and provide little ability to edit them after the fact.
Since Inkscape's approach is different than that of a CAD system, it
might make sense to work within the current system of doing things.
Instead of adding ways to draw individual shapes precisely, for
example, consider enhancing the node editor with those features
instead. All shapes then benefit, and you preserve the Inkscape
approach of drawing first and refining later. While I use CAD software
every day and understand that its approach is faster for engineering,
Inkscape is an art program, not a CAD program. Any added CAD features
should follow the artistic philosophy of gradual refinement rather
than the engineering approach of instant perfection.
Of course, this is just my own thinking based on my experience with
both types of software. Feel free to ignore me if you like.
-William Swanson
9:22 p.m.
> Let me know what you think of this plan, and let me know how I
can get
> to those geometry classes.
CAD systems, on
the other hand, require users to draw shapes perfectly the first time,
and provide little ability to edit them after the fact.
I've only had some experience with Unigraphics in an engeneering
class, but I don't recal it being hard to reposition pieces at all. It
was my first time with a CAD program, so maybe I just got proficient
at fixing my mistakes, or maybe it depends a lot on which program
you're using.
I'd just like to have exact positioning features, even for doing art
type things in Inkscape, it'd be nice to be able to precicely position
things. I end up using snap-to-grid, and the alignment tools a lot
right now, but if there were a way to precicely position things, I'd
only have to draw some of my shapes once.
As for where the geometry is, I'm pretty new to the code, but in src/,
sp-shape.h says "Base class for shapes, including <path> element", and
sp-item.h says "Some things pertinent to all visible shapes".
Also, there are sp-spiral.cpp, sp-star.cpp, sp-rect.cpp etc. and
sp-object-edit.cpp includes all the shapes .h files
Hope that helps. I'm new too,
--
Michael Moore
-------------------------
Creative photography for any occasion
http://elementsbycaroline.com
Full quality proofs
Online album
9:55 p.m.
Scott,
If I understand your previous posts, I think you are trying to create
some useful GIS cad tools (which is a great idea). Maybe you've
already thought about this, but one of Inkscape's strengths is the SVG
data format and there may be some great synergies with the GIS oriented
GML data formats and Google Earth's KML since all of these are XML
based. Perhaps a first step might be to have a process of
importing/exporting necessary data between these formats. This might
help in creating whatever data object class extensions might be needed
in Inkscape (most likely new GIS CAD classes that inherit existing
classes). I think the precision drawing techniques you're describing
will be methods in these new classes or even the more base classes.
John
Redefined Horizons wrote:
I've got an hour or two at the end of this work to get started on
my
CAD tools for Inkscape. (I checked out a couple of books on C++ from
my local library in case I get stuck on something.) :]
First let me ask a question, and then I'll explain my plan. (You guys
can let me know if the plan is feasible with Inkscape's architecture.)
Where can I find the classes used to represent Inkscape's geometries?
(I'm assuming that each geometry type is represented by a separate
class file. Let me know if this is incorrect.)
I've dowloaded the source code for Inkscape 0.44, but I couldn't find
a "geometry" folder in the "src" folder of the distribution. I
imagine
there would be a class file for rectangles, circles, elipses, lines,
polylines and polygons. (Unless rectangles are represented as
polylines and elipses as modified circles...)
Now, for my plan of attack...
Here is a basic description of my goal for the CAD tools:
Tools that allow the user to create the basic Inkscape geometries
using precise coordinate entry. (For example, the user could enter
coordinates into a dialog box for the two endpoints of a line and then
create that line, or they might enter the coordinate for the start
point of the line, and then an angle and distance that would be used
to compute the endpoint of the line.) Or the user might use other
tools to select the precise coodinates of existing geometries as the
input for such a tool, instead of entering the coordinates directly.
(For example, selecting the coordinate at the midpoint of a line and
the node of a polygon, and drawing the line with these exact
coordinates as the two endpoints.) These tools will also allow the
user to precisely modify existing geometries. (For example, move a
polygon by precisely selecting two coorinates on existing geometries
to compute the change in X and change in Y for the translation.)
Here is what I need to do:
[1] Design and implement what I call "coordinate selectors". These are
tools that allow very precise selection of points on the canvas.
Typically these points will be selected from existing geometries.I
would like to implement the following coordinate selectors for
Inkscape:
End Point (The coordinate at the end point of a line or polyline.)
Mid Point (The coordinate at the mid point of a line, polyline
segment, or polygon segment.)
Nearest Node (The coordinate at the node nearest to center of
selection window created by a mouse drag on the canvas.)
All Nodes (The coordinates of all nodes within a selection window
created by a mouse drag on the canvas.)
Perpendicular (The coordinate at point on a line, polyline segment,
polygon segment, or projection of any of these segments that is
perpendicular to another selected point.)
Intersection (The coordinate of the point at the intersection of two
or more lines, polyline segments, or polygon segments.)
Offset (The coordinate of a point created by projecting an offset
along the alignment or direction of two other points and a fixed
distance.)
Projected Intersection (The coordinate of a point located at the
projected intersection of any two lines, polyline segments, or polygon
segments.)
I'll get started by examing the geometry classes, which I will need to
use in my calculations for the coordinate tools. But I will also need
to figure out how to add a tool to Inkscapes user interface that
allows the user to drag a window on the canvas and then
programatically access the geometries or shapes that are contained by
or intersect that window. (Perhaps I can use the exisitng
pointer/selection tool in Inkscape?)
Let me know what you think of this plan, and let me know how I can get
to those geometry classes.
Scott Huey
P.S. - I can program the coordinate selectors in a way that allows
them to be used by other developer's tools, not just the ones I
design. For example, in OpenJUMP I am building coordinate selectors
that can store there selected coordinates on a "Coordinate Clipboard"
that can be accessed by the user or programatically.
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12:52 a.m.
The current geometry stuff is rather imprecise, slow, and inflexible. If
I've got my history right, various replacements have been proposed, yet none
accepted (perhaps code was used from them), yet this stuff has its ancestry
in sodipodi.
To finally come up with an end-all-be-all solution, the 2geom project was
started by a few inkscape developers.
http://sourceforge.net/projects/lib2geom . It's going along nicely, but
will still be a while until completion. There's some really nice stuff
already, and advanced algorithms in planning. It'll certainly be a more
elegant, fast, capable, and precise solution.
There's definitely room for more developers, though. Njh, resident math
genius, is working on his phd. Mental, programming guru, is working on his
comic. I, code janitor, am currently preparing for highschool (about 1200
pages of reading for language arts...).
If you'd like to actually get something functioning, and do it on inkscape's
current stuff, that's cool - 2geom might be a while. However, once it's at
a decent point of functionality, the current stuff will be torn out and
2geom placed in its stead. Everything that uses geometry stuff will have to
be signifigantly adapted. I'd suggest putting effort towards 2geom - your
CAD stuff will probably be easier and more elegant for it. You can add
features particularly required by your CAD stuff.
Stop by the jabber lib2geom@...132... if you'd like to help but
don't know what to do.
On 8/31/06, Redefined Horizons <redefined.horizons@...400...> wrote:
Where can I find the classes used to represent Inkscape's geometries?
(I'm assuming that each geometry type is represented by a separate
class file. Let me know if this is incorrect.)
12:39 p.m.
On 8/31/06, Redefined Horizons <redefined.horizons@...400...> wrote:
Where can I find the classes used to represent Inkscape's
geometries?
I'm not entirely sure what you mean by "geometries". Inkscape has
different kinds of objects, and their code is mostly in sp-*.cpp, for
example sp-rect, sp-path etc. Of course these files use many other
parts of the code. The purely geometric code is mostly in libnr/ and
in livarot/.
I've dowloaded the source code for Inkscape 0.44, but I
couldn't find
a "geometry" folder in the "src" folder of the distribution. I
imagine
there would be a class file for rectangles, circles, elipses, lines,
polylines and polygons. (Unless rectangles are represented as
polylines and elipses as modified circles...)
Yes, all shapes except rectangles are represented as paths in
Inkscape. But they nevertheless are separate classes each with its own
behavior and controls.
Tools that allow the user to create the basic Inkscape geometries
using precise coordinate entry. (For example, the user could enter
coordinates into a dialog box for the two endpoints of a line and then
create that line, or they might enter the coordinate for the start
point of the line, and then an angle and distance that would be used
to compute the endpoint of the line.)
Excellent idea, and the natural place for these precise controls is on
each tool's controls bar. For example, for rectangles, we already have
numeric boxes for width, height, and rounding radii; you can add
another couple of boxes for x/y origin. For the Pen tool, we currently
have no controls at all, but you can add them for setting precise
coordinates of the next point.
Or the user might use other
tools to select the precise coodinates of existing geometries as the
input for such a tool, instead of entering the coordinates directly.
For that we already have the Paste size family of commands. You can
propose other commands along the same lines.
(For example, selecting the coordinate at the midpoint of a line and
the node of a polygon, and drawing the line with these exact
coordinates as the two endpoints.)
This is much easier achieved by snapping, and is already mostly
possible. Open Document properties, Snap tab, and turn on "snap nodes
to objects" and "snap to object nodes" below it. After that the Pen
tool and Node tool will snap nodes e.g. to the corners of a rectangle
(though not to its center yet, but this is easy to add).
These tools will also allow the
user to precisely modify existing geometries. (For example, move a
polygon by precisely selecting two coorinates on existing geometries
to compute the change in X and change in Y for the translation.)
Again, this is a matter of making the controls in the bar smart
enough, so that others change their values accordingly when you change
the value of one of them. Perhaps you'll need some locks and option
buttons as well to modify this behavior.
So, to summarize, from your use cases I don't see a need for any new
tools or concepts. Everything is achievable with what we already have
or with a logical extension of it.
[1] Design and implement what I call "coordinate
selectors". These are
tools that allow very precise selection of points on the canvas.
Typically these points will be selected from existing geometries.I
would like to implement the following coordinate selectors for
Inkscape:
I'm not sure what you mean by "coordinate selector". Can you describe
step-by-step how it would work? Is this a new tool? Where would it put
the selected coordinates? etc.
--
bulia byak
Inkscape. Draw Freely.
http://www.inkscape.org
6298
days inactive
6301
days old
inkscape-devel@lists.inkscape.org
5 comments
6 participants
participants (6)
-
Bot Builder -
bulia byak -
jtaber -
Michael Moore -
Redefined Horizons -
William Swanson