topic couple of problems with a 2d object in Libraries & objects

couple of problems with a 2d object

vistasp — Fri, 07 Nov 2008 15:57:22 GMT

I hope someone can point out what I'm doing wrong. In this object (I want to use it for drainage layouts on site plans) I've been able to make the line itself stretchy. There's also a nice little part that uprights the text automatically

Two things aren't working despite my best efforts:

1. Despite a moving hotspot, the text stubbornly refuses to budge!

2. At 90° & 270° the object reduces itself to a little green point. I presume this has something to do with the fact that Cos 90 & 270 are both zero but all the IF-THEN statements that I tried didn't seem to make the slightest difference to this vanishing act.

TIA

Re: couple of problems with a 2d object

Anonymous — Fri, 07 Nov 2008 19:49:46 GMT

Hello Vistasp,
On the mater of the green dot, you have of course, a divide by zero error
at line angle 90° and 270° because you have defined lin_ang=ATN(ver/hor)
The fix for this, I think, is just before the lin_ang definition put

eps=0.00000001

if hor<eps and hor>-eps then hor=eps

Granted, this introduces a small error in the geometry which
you may not be able to tolerate.

I am still trying to figure out the stubborn text moving hotspot.
It's not that it doesn't move but it's spring loaded
If I get anywhere with this I will post back.
Peter Devlin

Re: couple of problems with a 2d object

Anonymous — Fri, 07 Nov 2008 20:17:44 GMT

Hello Vistasp,
Well, I suspected that defining the variable "thor" was causing
the spring loaded effect. If you comment out the three IF statements
that define "thor" then you can slide the text as you want to.
This of course disables the placement of the text to the left, right, or center.
I am not sure you can have it both ways.
Peter Devlin

Re: couple of problems with a 2d object

Anonymous — Fri, 07 Nov 2008 21:45:52 GMT

Hello,

Just adding and choosing fourth option makes it possible to have both ways.

VALUES "halign" "left", "centre", "right", "free"

--
Regards, Juha

Re: couple of problems with a 2d object

vistasp — Sat, 08 Nov 2008 03:28:38 GMT

Peter wrote:
On the mater of the green dot, you have of course, a divide by zero error
at line angle 90° and 270° because you have defined lin_ang=ATN(ver/hor)
The fix for this, I think, is just before the lin_ang definition put

Thanks Peter. I'll try those IF-THENs before the lin_ang definition and see if they work. If it still fails, I guess I'll have to live with a tiny inaccuracy.

Alternatively, as and when I need it at that angle, I can rotate the object instead of stretching it. Still, just wanted to idiot-proof it...

Re: couple of problems with a 2d object

vistasp — Sat, 08 Nov 2008 03:35:23 GMT

Peter wrote:
Well, I suspected that defining the variable "thor" was causing the spring loaded effect. If you comment out the three IF statements
that define "thor" then you can slide the text as you want to. This of course disables the placement of the text to the left, right, or centre.
I am not sure you can have it both ways.

Peter, in an earlier version (!) of this object, there was no left/centre/right option. I intended the text to be placed halfway along the line and manually move it where suitable. However, since the value of "thor" was derived (as it is even now), the text sprang back as you pointed out.

When the value of "thor" is given directly in the parameters, it slides perfectly. A calculated value, for some reason, doesn't work.

Re: couple of problems with a 2d object

vistasp — Sat, 08 Nov 2008 03:37:27 GMT

Juha wrote:
Just adding and choosing fourth option makes it possible to have both ways.

VALUES "halign" "left", "centre", "right", "free"

That's a good idea Juha. I'll add that option and show the parameter "thor" for manual value input.

Will post back if successful.

Re: couple of problems with a 2d object

Anonymous — Sat, 08 Nov 2008 09:49:15 GMT

Hi Vistap,

You have to define a couple of hotspots (x, y) for both extremities of your line,
and write some statements to avoid trigonometry errors.

Attached an object similar to yours.
It is metric, you will have to make somme changes for imperial units.

Re: couple of problems with a 2d object

vistasp — Sat, 08 Nov 2008 11:25:37 GMT

Nice one Olvier! If I had your object before I started, I wouldn't have started at all. 😉

On the other hand, I wouldn't have learned anything either. Except this:

	if req ("GDL_version") > 1.5 then    ! AC 10
		dim fontnames[]
		rrr = request ("FONTNAMES_LIST", "", fontnames)
		values "fontType" fontnames, custom
	else
		values "fontType" 'Arial', 'Verdana', 'Helvetica', 'Geneva', 'Times', 'Georgia', 'Courier', custom
	endif

I didn't know the option to list all system fonts existed although I'd always wished for it. Thank you for this as well as your stretchy line. I'm not going to change the units - here in India, we are "bi-lingual" when it comes to units.

We need some kind of "tip of the week" to make us less experienced chaps aware of great stuff like this. Something like "Hot Tip Harry" does for the AutoCad world.

Re: couple of problems with a 2d object

Anonymous — Sat, 08 Nov 2008 16:00:10 GMT

Glad if this can help.
May be you already know the GDL Technical Standards.
This is a valuable source of information. Added to the GDL Reference Guide, almost everything is there,
(except the new status code 128 for TUBE) 😉. Please, GS ...

Re: couple of problems with a 2d object

Anonymous — Sat, 08 Nov 2008 17:43:53 GMT

Hello Olivier,
I looked at the code for "Stretchy Line.gsm". Impressive !!.
I see that you had to go through quite a bit
to avoid using the trigonometry functions
arcsin, arccos, and arctangent all of which
involve ratios and thus the possibility of divide by zero errors.
Recently, I had been wondering about ways to avoid these
trig functions in GDL code and you have shown me one
approach, possibly the only one, for doing this.
Thank you !
Peter Devlin

Re: couple of problems with a 2d object

Anonymous — Sat, 08 Nov 2008 20:42:31 GMT

Hi Peter,

I don't know any method. I would say observation, some logic, + trial and error.
Just divide the circle in four quadrants, and see what happens. Then take the conclusions.

Once it is done, you can re-use these statements again and again in other scripts, macros, etc... It is basic trigonometry.
Nothing special, I only use sin, cos, tan & atn functions, that's all.

The point is to avoid the divide by zero error, trigo or not, as you pointed.

Re: couple of problems with a 2d object

Anonymous — Sun, 09 Nov 2008 16:46:28 GMT

Hello Olivier,
Looking at your code in the master script I see you do use
the atn() function but you have very cleverly written conditional
statements that prevent the denominator from ever being zero.
I see how you have used dividing the circle into four quadrants
to define the angle where x becomes zero without using the
atn() function for these special cases. I say again, very clever.
If you don't mind Olivier, I would like to steal your code and
use it in my scripts.
Thanks again,
Peter

Re: couple of problems with a 2d object

Anonymous — Sun, 09 Nov 2008 19:26:40 GMT

Peter,

No need to ask, once it is posted, it's free.
Thanks anyway.

Re: couple of problems with a 2d object

vistasp — Mon, 10 Nov 2008 10:45:17 GMT

Olivier wrote:
Glad if this can help.
May be you already know the GDL Technical Standards.
This is a valuable source of information. Added to the GDL Reference Guide, almost everything is there,
(except the new status code 128 for TUBE) 😉. Please, GS ...

I'd visited the developer docs when I was a total newbie and, at the time, hastily clicked the back button. Usually, there's no time for developing anything, but a relative slow-down in work has suddenly made this section very interesting indeed.

Thank you for reminding me of it. I've been looking at selfGDL a lot these days as well - have to use babelfish a lot of course. 😉

Re: couple of problems with a 2d object

vistasp — Mon, 24 Nov 2008 16:36:09 GMT

Olivier, I've taken the stretchy line you created and added some functionality to it.

Mainly the object can now:

1. write levels at the start and end points of line. This text also slides along the line.

2. dynamically calculate the end point's level based on a given slope. Optionally, the end point level can be manually written.

Comments and suggestions are welcome.

Here's a screenshot:

Re: couple of problems with a 2d object

vistasp — Mon, 24 Nov 2008 16:37:08 GMT

And here's the object.

Re: couple of problems with a 2d object

Djordje — Tue, 25 Nov 2008 18:19:46 GMT

vistasp wrote:
And here's the object.

To the Depository, please!

Re: couple of problems with a 2d object

vistasp — Thu, 27 Nov 2008 10:06:48 GMT

Djordje wrote:
To the Depository, please!

Was waiting for bug reports but, since I haven't heard from anyone, the object now resides in the depository.

EDIT: 28.11.2008

A couple of errors were found by Olivier. These have been fixed. If anyone has downloaded the original object, please do so again. Sorry!