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Drawing Perspective
williamj Offline
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#31
12-09-2012, 11:06 PM (This post was last modified: 12-09-2012, 11:13 PM by williamj.)
(12-09-2012, 06:50 PM)i44troll Wrote: Bill, give us a sample drawing. I think I know what you're wanting but I'm not 100% sure.

Chris,

Thanks for the response. I hope the attachment clarifies what I was trying to say. Though the line tool in question snaps to a circle, the same line tool does not snap to an ellipse, a member of the "Circle" family as it were. Drawing these lines by hand, with out the snap feature, results in a very poor Isometric drawing that the eye quickly sees as misaligned drawing segments. I don't know or remember off hand if the same applies to "arcs".

However, I am now able to properly size and position two ellipses appropriately in an Isometric layout. Takes a little doing but not too difficult.

hope this helps,
williamj

   
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i44troll Offline
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#32
12-09-2012, 11:43 PM
Bill,
The drawing shows two circles, no ellipses. Draw a picture using the ellipses instead so I can see the problem as you see it
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williamj Offline
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#33
12-10-2012, 09:40 AM
(12-09-2012, 11:43 PM)i44troll Wrote: Bill,
The drawing shows two circles, no ellipses. Draw a picture using the ellipses instead so I can see the problem as you see it

Sorry 'bout that Chris.

   
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i44troll Offline
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#34
12-10-2012, 02:49 PM (This post was last modified: 12-10-2012, 02:52 PM by i44troll.)
Bill,

Try this.........
   
   
   
   
   
   
   
   
   
   
This actually doesn't take as long as it looks, still, it would be nice to be able to snap to an ellipse
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jw48 Offline
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#35
12-10-2012, 04:28 PM
Chris and Bill

That's still an approximation, but probably as near as we're going to get.

I tried going back to Euclid, finding the foci of the ellipses and then various geometrical constructions to create the common tangent.

I failed!

Regards
John
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williamj Offline
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#36
12-10-2012, 04:48 PM (This post was last modified: 12-10-2012, 04:50 PM by williamj.)
(12-10-2012, 02:49 PM)i44troll Wrote: Bill,

Try this.........
This actually doesn't take as long as it looks, still, it would be nice to be able to snap to an ellipse

Wow Chris, I am impressed! I could see where you were going the moment you said "put in some arcs".

You know it's really strange the things you stumble over while looking for something else. While I was playing around with this stuff I tried rotating the ellipses 30 degrees to line up with the perpendicular lines. I was really surprised at the results. Am going to play with it a little more but I post the results for all to see.

John,

Thanks for the response and for the attempt. It's all very much appreciated.

Thanks whole bunches!
williamj
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mysundial Offline
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#37
12-10-2012, 09:17 PM
Good Day!

I came up with something that may get you a bit closer.

1. Go to the Edit tab and select E (Edit object data). Select the ellipse.
2. Record the value of the Angle.
3. Draw an angled line from centre of the ellipse at an angle of 90 plus Angle. This line can be drawn beyond the boundary of the ellipse.
4. Mirror this line but Copy it first.

Now you have two intersection points that you can snap to. Draw a line with two points doesn't want to snap but draw a continued line will.

Carl
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williamj Offline
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#38
12-10-2012, 11:26 PM
(12-10-2012, 09:17 PM)mysundial Wrote: Good Day!

I came up with something that may get you a bit closer.

1. Go to the Edit tab and select E (Edit object data). Select the ellipse.
2. Record the value of the Angle.
3. Draw an angled line from centre of the ellipse at an angle of 90 plus Angle. This line can be drawn beyond the boundary of the ellipse.
4. Mirror this line but Copy it first.

Now you have two intersection points that you can snap to. Draw a line with two points doesn't want to snap but draw a continued line will.

Carl

Carl,

Great Day back atcha!

Thanks for your response. Great tip on the continued line snapping to the intersection of the line and the ellipse, gonna try it tomorrow.

Reading instructions always makes me dizzy, could you post a quick drawing to illustrate your method?

It's always way more fun when more people participate.
williamj
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i44troll Offline
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#39
12-10-2012, 11:30 PM
Hello Carl!

Good to here from you again!

I might add something here as well...
We may not be able to snap a line with two endpoints to the intersection BUT we are able to place a point at the intersection first (believe it or not!) THEN we CAN snap our line endpoint to the point.

Chris
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jw48 Offline
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#40
12-13-2012, 06:23 PM
Tangent to two ellipses:

Even the mighty AutoCad (LT) hiccups on this one. See here

The mathematicians scratch their heads, but do have answers. See here

Regards
John
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