Convex or concave angle between faces? - Grasshopper2024-03-28T16:03:22Zhttps://www.grasshopper3d.com/forum/topics/convex-or-concave-angle-between-faces?feed=yes&xn_auth=nothanks taz for the reply and…tag:www.grasshopper3d.com,2015-10-18:2985220:Comment:13811742015-10-18T15:39:17.545ZAlexSphttps://www.grasshopper3d.com/profile/AlexSp
<p>thanks taz for the reply and the info about sandbox. looks very usefull.</p>
<p></p>
<p>Actually I was looking before alot at your post here:</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from" target="_blank">http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from</a></p>
<p>and here:…</p>
<p></p>
<p>thanks taz for the reply and the info about sandbox. looks very usefull.</p>
<p></p>
<p>Actually I was looking before alot at your post here:</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from" target="_blank">http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from</a></p>
<p>and here:</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/finding-the-neighboring-cell?id=2985220%3ATopic%3A135232&page=3#comments" target="_blank">http://www.grasshopper3d.com/forum/topics/finding-the-neighboring-cell?id=2985220%3ATopic%3A135232&page=3#comments</a></p>
<p></p>
<p>Your posts helped me a lot to get to the point where I'm now. But still I'm trying to fix the problem posted above. I need to know for every surface in a brep the angles to the adjecent surfaces. This works almost fine and the third vector w helped alot to decide which direction to measure. But due to the strange geometry of srf 1 the centerpoint lies very high and once the angle between uw and vw is >90° and on the other srf <90°. Therefore I got at this points both angles. </p>
<p></p>
<p>I thought about to filter this points by measuring also the angles between u and v to a reverse vetor of w (lets call the reverse w'). If I got then two different values for uw and uw' I found the positions where the angles measuring is not correct.</p>
<p>Or is there a smarter way to do it?</p>
<p></p>
<p>Could I ask, if you could share your old grasshopper file you created here:</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from" target="_blank">http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from</a></p>
<p></p>
<p>Thanks!</p> This old discussion may be us…tag:www.grasshopper3d.com,2015-10-16:2985220:Comment:13802372015-10-16T15:53:02.198Ztazhttps://www.grasshopper3d.com/profile/taz
<p>This old discussion may be useful if you've got a BRep with all the surfaces joined (thus a consistent orientation of the surface normals). Face topology for surfaces is a lot more straightforward these days with add-on's like Sandbox.</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from" target="_blank">http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from</a></p>
<p>This old discussion may be useful if you've got a BRep with all the surfaces joined (thus a consistent orientation of the surface normals). Face topology for surfaces is a lot more straightforward these days with add-on's like Sandbox.</p>
<p><a href="http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from" target="_blank">http://www.grasshopper3d.com/forum/topics/q-specific-pairings-from</a></p> forgot to attach the gh file.
tag:www.grasshopper3d.com,2015-10-16:2985220:Comment:13799542015-10-16T09:31:26.109ZAlexSphttps://www.grasshopper3d.com/profile/AlexSp
<p>forgot to attach the gh file.</p>
<p></p>
<p>forgot to attach the gh file.</p>
<p></p> Hi Thomas,
I found this post…tag:www.grasshopper3d.com,2015-10-16:2985220:Comment:13798752015-10-16T09:28:11.858ZAlexSphttps://www.grasshopper3d.com/profile/AlexSp
<p>Hi Thomas,</p>
<p>I found this post because I'm facing a similar problem. I like the idea of introducing a third vector and calculate the angle between them. I have implemented your "anglebetweenfaces_idea" in my task. </p>
<p>I have the problem that for some faces, u >90° related to w and v<90°. So I get the angle and the reflex angle between this two faces.</p>
<p></p>
<p>Please see the red grouped componants in the gh file.…</p>
<p></p>
<p></p>
<p>Hi Thomas,</p>
<p>I found this post because I'm facing a similar problem. I like the idea of introducing a third vector and calculate the angle between them. I have implemented your "anglebetweenfaces_idea" in my task. </p>
<p>I have the problem that for some faces, u >90° related to w and v<90°. So I get the angle and the reflex angle between this two faces.</p>
<p></p>
<p>Please see the red grouped componants in the gh file.</p>
<p></p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2769048052?profile=original"><img width="721" class="align-full" src="http://storage.ning.com/topology/rest/1.0/file/get/2769048052?profile=RESIZE_1024x1024" width="721"/></a></p>
<p>Has someone an idea how I can get rid of the two different angles? Maybe by comparing the angle between u-w and v-w?</p>
<p></p>
<p>Thanks and best regards,</p>
<p>Alex</p> Thats right.tag:www.grasshopper3d.com,2013-11-10:2985220:Comment:9550912013-11-10T14:38:26.182Zmichael sprinzlhttps://www.grasshopper3d.com/profile/Sprinzl
Thats right.
Thats right. Hi Michael!
That's right! Pay…tag:www.grasshopper3d.com,2013-11-10:2985220:Comment:9552422013-11-10T13:58:40.380ZThomashttps://www.grasshopper3d.com/profile/TJO950
<p>Hi Michael!</p>
<p>That's right! Pay attention on rounding errors e.g. for checking orthogonality use Abs(DotProduct) < Tolerance instead of DotProduct == 0.</p>
<p>For this problem we don't have to check vectors for parallelity. We use the scalar product to determine if an angle is sharp or obtuse (see Hannes' post). Instead of multiplying the normal vectors we have to multiply one normal vector with a vector that connects both faces.</p>
<p>Hi Michael!</p>
<p>That's right! Pay attention on rounding errors e.g. for checking orthogonality use Abs(DotProduct) < Tolerance instead of DotProduct == 0.</p>
<p>For this problem we don't have to check vectors for parallelity. We use the scalar product to determine if an angle is sharp or obtuse (see Hannes' post). Instead of multiplying the normal vectors we have to multiply one normal vector with a vector that connects both faces.</p> Ok a very simple but very imp…tag:www.grasshopper3d.com,2013-11-10:2985220:Comment:9553102013-11-10T10:07:29.294Zmichael sprinzlhttps://www.grasshopper3d.com/profile/Sprinzl
Ok a very simple but very important question.<br />
First.. Take the two normal vectors from the surface mesh whatever.<br />
second... Make sure they have the length of 1. ( vector3d.unit).<br />
third multiply the vectors.<br />
if result is 1 threy are parralell and show in same direction. If they are -1 they are parrallel and show in oposite direction. If they are 0 they are orthogonal.
Ok a very simple but very important question.<br />
First.. Take the two normal vectors from the surface mesh whatever.<br />
second... Make sure they have the length of 1. ( vector3d.unit).<br />
third multiply the vectors.<br />
if result is 1 threy are parralell and show in same direction. If they are -1 they are parrallel and show in oposite direction. If they are 0 they are orthogonal. Hannes,
thanks for your comme…tag:www.grasshopper3d.com,2013-11-09:2985220:Comment:9548402013-11-09T16:55:53.965ZLeohttps://www.grasshopper3d.com/profile/Leo360
<p>Hannes,</p>
<p>thanks for your comment.</p>
<p>I am trying to know something about time consuming in this component, but the profiler widget doesn't show any information on it. <br/>Does it signify that the time consuming it is not relevant for that component in my case?</p>
<p>Hannes,</p>
<p>thanks for your comment.</p>
<p>I am trying to know something about time consuming in this component, but the profiler widget doesn't show any information on it. <br/>Does it signify that the time consuming it is not relevant for that component in my case?</p> TJO,
thanks for your reply an…tag:www.grasshopper3d.com,2013-11-09:2985220:Comment:9547272013-11-09T16:19:54.817ZLeohttps://www.grasshopper3d.com/profile/Leo360
<p>TJO,</p>
<p>thanks for your reply and detailed explanation!</p>
<p>I understood the idea. Works fine.</p>
<p>Thank you very much! </p>
<p>TJO,</p>
<p>thanks for your reply and detailed explanation!</p>
<p>I understood the idea. Works fine.</p>
<p>Thank you very much! </p> Thanks!
I use the pick'n'choo…tag:www.grasshopper3d.com,2013-11-09:2985220:Comment:9548302013-11-09T12:56:34.566ZThomashttps://www.grasshopper3d.com/profile/TJO950
<p>Thanks!</p>
<p>I use the pick'n'choose component like you described it to get the angle between u and v. In my example file i actually get the opposite one but that should not be a problem.</p>
<p>From this angle the eval component computes the angle between the faces by subtracting 180° (or subtract the angle from 180° if you picked the other angle in the previous step). The problem is that you get e.g. -75° instead of 285°.</p>
<p>For further calculations a negative angle would not be a…</p>
<p>Thanks!</p>
<p>I use the pick'n'choose component like you described it to get the angle between u and v. In my example file i actually get the opposite one but that should not be a problem.</p>
<p>From this angle the eval component computes the angle between the faces by subtracting 180° (or subtract the angle from 180° if you picked the other angle in the previous step). The problem is that you get e.g. -75° instead of 285°.</p>
<p>For further calculations a negative angle would not be a problem but is not common for dimensioning. So i add 360° and use the modulo operation to get only positive angles. Of course you can do that also with pick'n'choose.</p>