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# Roof intersection line rendering

## Question

Pitch at blue roof is not the same as at orange roof. Therefore, the valley is not at 45? in top/plan view. Currently I have to do some trigonometry in my handheld calculator to draw the valley angle. And the green arch-top dormer will have to be approximated in the 2D roof plan.

I wish for roof intersections to render as lines in Hidden Line Rendering. In other words, I want to take advantage of the computing power of a CAD software so that things that model easily can be converted quickly into equally accurate line drawings.

## Recommended Posts

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Why not just enter the annotations and add the missing lines? I realize this is a work around, but hey, that's what;s needed sometimes ;-)

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Why not just enter the annotations and add the missing lines?

And click on what points for the line segment? Sometimes the situation is like this:

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Worksheet to determine location of Peak#2 from Gable of Peak#1:

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Question I have is....are you creating two seperate roof structures at different pitches that collide with each other without trimming to the break at the valleys. If so than your collision intersection will never produce a hard line on a hidden line rendering because there is no collison object created that the system can see.

However if you take the two roof objects and convert to lines with hidden line option selected than using that drawing as a guide to create roof faces you will create a roof that provides absolute accuracy in the the valley cut.

I've done all this using the power of the CAD that VW has provided.

Pete Anthony

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the easiest way to do this is to edit the 3D roof, edit both roofs so that they are cut exactly. It's not easy to write this, it?s better with pictures and movies, in fact it?s covered in my Architect tutorial.

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..if you take the two roof objects and convert to lines with hidden line option selected than using that drawing as ae guide to create roof faces you will create a roof that provides absolute accuracy in the the valley cut...

Wrong! Pete, have you ever tried doing it with two different roof pitches? You can't. That's the point-- how do you find the valley angle in plan view?

panthony and archoncad are totally missing the concept of my wish item. (Jonathan, why are you always trying to sell your manuals here?) islandmon, while your worksheet seems to be a viable workaround, it's way too complicated and even more time consuming than my hand-held calculator method! I press only two functions on my calculator! (FYI, you can actually do it without the cosine function)

Again, any CAD software that claims to be hybrid 2D/3D ought to generate these odd valley angles without forcing the user to press trig keys on a separate calculator.

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And hopefully y'all aren't judging me by the color of my roof...

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Arch.Ken

Here is how you find the valley lines in 2d using VW....

And here is an example of 5 complete roof hidden lines using the way stated above.

I hope this answers your question and dispells any confusion in the ability of locating a work-around.

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I agree with the original message post from Arch.Ken. The software should be able to compute and render the intersections of 3D objects as lines. Ideally, it would be a preference that the user can turn on/off.

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Arch.Ken,

The worksheet was created, only, to illustrate the problem for those who are interested.

The cos just computes the length based on the run as a closure function for clarity.

The easiest CAD solution is to just use 3d Views & place 3d Loci keyed to pitches.Then view in TopPlan... No big deal !

The ideal 'wishlist' CAD solution is for the software to compute and place the 3d Loci for the User.

In the future I shall avoid offering 'troublesome' worksheet analysis assuming that every User operates at your high level of intensity.

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Fine.

We don't need any improvements.

Otherwise we'd all be accused of "operating at such a high level of intensity." :rolleyes:

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I'm with you Ken.

Whilst there are work arounds for this problem its something a cad program should be able to automate.

I want to be able to join intersecting roof faces in the same manner as joining walls. And in the same vein since we no longer have to manually join walls to a roof I'm hanging out for the day we don't have to maually edit roof plane intersections

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I agree that this is an essential needed feature. We've discussed the shortcomings of hidden line rendering in other threads, and this falls in the general category of creating lines at the intersection of solid objects. With this and a context-sensitive outline of objects seen against space or more distant objects, the hidden line rendering mode would actually be presentable.

The fact that a calculation can be done to draw the line shows that an alogorithm can be created to do it automatically!

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