# [Blindmath] Determining shape coordinates when using SVGDraw01

Richard Baldwin baldwin at dickbaldwin.com
Fri Dec 23 21:54:38 CST 2011

```Hi Pranav and Ben,

I imagine it would be fairly difficult, but I will give it some thought.

I also haven't used Autocad since playing with a DOS version many years ago.

Dick Baldwin

On Fri, Dec 23, 2011 at 8:36 PM, Pranav Lal <pranav.lal at gmail.com> wrote:

> Hi Ben,
>
> This is interesting.  I've never used any other CAD program though I had
> tried a very old version of AutoCAD which was accessible during the DOS
> days.  < Chuckle
>
> Richard, how easy would it be to add the features Ben mentions?  Would
> other
> users find these useful?
>
> Pranav
>
> -----Original Message-----
> From: blindmath-bounces at nfbnet.org [mailto:blindmath-bounces at nfbnet.org]
> On
> Behalf Of Ben Humphreys
> Sent: Saturday, December 24, 2011 2:10 AM
> To: Blind Math list for those interested in mathematics
> Subject: Re: [Blindmath] Determining shape coordinates when using SVGDraw01
>
> In a CAD program such as AutoCAD, there are two features that make
> drawing these kinds of things much easier:
>
> 1.  One line segment or edge of an existing shape can "snap" to
> another.  This is typically done by moving the mouse "close" to the
> edge of a segment or shape and the "snap-to" is indicated visually
> with a small pink rectangle if memory serves.
>
> 2.  In addition to drawing using pairs of x-y coordinates, polor
> coordinates can be used as well.  So instead of saying something like:
>
> Line from 0, 0 to 3, 4 you could say:
> Line from 0, 0  , length 5 at a 60 degree angle
>
> In such a system, the actual exact coordinates take a back seat yet
> the length of lines and angles is very precise.  In order to
> replicate the "snap-to" functionality present in a CAD program, SVG
> Draw would need to allow naming of objects (which I think it already
> does) and then the ability to specify a "point" on that object, such
> as top, left, right, bottom, midpoint, intersection, etc
>
> In this way, you could assemble objects using lines that connect to
> the ends of other lines or edges or midpoints of other objects
> without regard to their coordinates.
>
> I suspect implementing some of this would represent a fair bit of
> work, since we're talking features typically found in a CAD
> program.  But the level of flexability would be improved marketdly I
> believe.
>
> Ben
>
> At 08:45 AM 12/22/2011, you wrote:
> >Hi all,
> >
> >I am trying to draw things like tables, chairs etc using SVGDraw01. One
> >problem I have is that if I try to draw something like a rhombus, I need
> to
> >get the coordinates myself. My civil engineer dad draws the shape on paper
> >and then gets the coordinates. However, in a program, I suspect I will
> have
> >to use a different approach since I cannot draw the shape and then derive
> >the coordinates. What approach should this be? Do I need to use equations
> of
> >shapes or is this a simpler problem?
> >
> >Pranav
> >
> >
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--
Richard G. Baldwin (Dick Baldwin)
Home of Baldwin's on-line Java Tutorials
http://www.DickBaldwin.com

Professor of Computer Information Technology
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(512) 223-4758
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```