Hi, I use C.a.R for descriptive geometry ...to present to students some constructions step by step. I want to thank you for your work, its really great tool. But I have one problem, for some constructions i need to show just part of the conic (for example when i want to draw a cylinder in axonometric projection, the part of one conic should be invisible). Is it possible to solve this problem with current version? Or could you add this tool?

Thanks for answer Mirka T.

One more information on loci

Z.u.L. is great drawing loci. I would greatly appreciate one more information: this locus is a conic (or a line) or not ? I think that it is not difficult to implement. Maybe it would be possible also to say the type of conic it is, perhaps allowing some imprecision for the parabola. I suggest that you could add a field in the properties panel with this information, that should be very useful while trying to solve problems by ruler and compass.

Giovanni Artico 2008/07/08 22:00

Transparent points

CaR seems to have the unique (and, to me, rather annoying) feature of transparent points. When the line thickness is selected as thin, points are little circles (or even more weird — squares) with transparent interior. I can make the points invisible, or into enormous blobs by choosing thicker line, but what I would like, and what is completely standard in drawing, is a small circle with white (background coloured) non-transparent interior. If there is a way to do this, it doesn’t seem to be obvious...

I implemented that for a test in Beta 8. I like it. Thanks for the idea. — Rene Grothmann (Admin) 2008/02/20 17:03

Thank you, for listening to users, and for all the work. A few related suggestions. I think there needs to be an intermediate size of solid dots, between virtually invisible (when lines are chosen thin) and enormous (when lines are selected thick). The same would be nice for line thickness in general: now, ‘thin’ is thin but ‘thick’ is too thick for a professional looking math or technical drawing, so for most purposes there is only one line width. Similarly, it would be nice to have a smaller right angle sign, and even more useful, some ways to mark equal angles and segments (as one does in a proof, with one, two or three strokes, or a double angle sign). How about a couple of extra arrowheads for vectors, including the standard technical solid triangle and may be a white one? I realize CaR is not intended to replace Autocad, but reducing the need to reedit the image for publication and a more professional look for web applications will make it even more attractive.

Thanks for the input!
  • I do not understand the first point. Dots are not chosen by line size.
  • I agree, that thick lines are now too thick, since I changed the default line size to 1.5 pixels. I will fix that.
  • For a “professional” output, you should use the graphics preview with scaling, choosing the sizes in real world units.
  • You should set the angles to the small size for rectangular angles.
  • The marking of things (angles, lines circles) with one, two, or three strokes could be implemented in a macro. I once did that, but never used it, since colors are so much better for the purpose. Anyway, it is an idea to think about, maybe as a macro, or a setting.
  • I do agree about vectors with triangle ends. This would look good.

As you say, C.a.R. is not a CAD program. I do not even want to start a race for the many features a good CAD program should have.

Thanks for the ideas! — Rene Grothmann (Admin) 2008/02/22 09:15

One point trace

This is an exemplar situation: you want to draw a parabola having focus and directrix; so you need five points; you take a point on the directrix, make two perpendiculars and draw a point at the intersection: it would be nice that this point could create a trace (another point behind it, but free), so you can move your point on the directrix and construct another point and so on, leaving the old points on the figure. Obviously if you move the focus or the directrix these points are no longer on the parabola, but this is not a problem. So this is what I suggest: a trace that photographs the current situation of an object, duplicating it.

Giovanni Artico 2007/02/28 18:31

I don’t know exactly, if I understand you correctly. If you want to remember the position of a point, you can create a fixed point at its current position by shift-clicking on it with the point tool. This should already solve your problem. I use it to show that a certain curve is a quadric, generating 5 points in this way and a quadric through the points. Another solution is to create an ordinary automatic track object, take it into the construction as an object, then fixing points on it. — Rene Grothmann (Admin) 2007/03/01 08:29
This solves my problem. I must read more carefully the manual. Many thanks. I think you can remove this entry from the list. — Giovanni Artico 2007/03/02 07:29
I leave it here for others to read. Most features of the program are unknown to most users :-)Rene Grothmann (Admin) 2007/03/05 13:23

Delete objects in the new object list

This object list feature in the 4.08 is really great ! I saw it was possible to do a multiple selection in the list and change their properties with an “Edit” contextual menu... But would it be possible to have an “Delete” contextual menu (or a supp keyboard key action) which could delete all the objects that are selected (And also of course all the objects which depend on them). — Eric Hakenholz 2006/01/16 19:47

In Version 4.09, this list will have learned to do more. Deleting and editing conditions is among the added things. — Rene Grothmann (Admin) 2006/01/19 09:54

Organizing macros

Put into a seperate page. — Rene Grothmann (Admin) 2006/01/07 18:46

Macro Manegement

Server Communication

Discussion moved to Server Communication.

Window Functions

Is there a way to access, within an expression, coordinates of the visible area of the window ? For example the zoom level, the coordinates of the upper left corner, and of the bottom right.

Solved in Version 4 — Rene Grothmann (Admin) 2006/01/06 15:06

Object Panel

It would be great if we could have interaction between the description and the construction like these:

  1. To have both windows working simultaneously
  2. To select an objetc on construction and have it bold on description, and viceversa
  3. Possibility to select an object on the description to construct. For example, if I want to draw a perpendicular line by a point P24, select the tool peprpendicular line, the line to which it must be perpendicular and then the point P24 on the description.
  4. To have some information about objects that are not visible on screen. For example, if I have I1 intersection between one line and a segment, the description could say “inexistent”.

I think these functions would be great in teaching geometry at elementary level, to work the link between the visual register and the language.And could be helpful in managing very complex constructions.

I admit that this would be nice. The only sensible way to do this, is to add a scrolling panel to the right or left of the construction window. GeoGebra has that. I do not really think, this is a necessity, but it would be nice to have. — Rene Grothmann (Admin) 2005/12/22 19:22

Internal Scripting

Internal scripting is on my agenda. Event driven scripts could create just any action in C.a.R. I could use my internal language for constructions for this purpose. However, in the course of the Intergeo Project another solution might evolve.

todo.txt · Last modified: 2009/11/30 14:44 by mirka
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