View Full Version : Double edges...inverted polygons...err...

05 May 2006, 02:55 AM
so i finally thought i had gotten the hang of how modeling worked in XSI...and yet again i find something new that confuses the crud outta me...

double edges and inverted polygons.

every 5min i run into some polygon that'll either want to be inverted from the rest, or have double edges, both which i recon are bad things, especially as i can have continious edges running through em =//

so in this example...add polygon tool. it'll become inverted...if i invert it again ive got double edges..

guy over at the freenode #XSI chat told me that it was cause something was "messed up" with the areas around polygon. though i couldnt find anything that seemed wrong.

05 May 2006, 03:56 AM
you might have duplicated the edges around that poly without noticing, that would create some polys with 0 surface, and in that case the heuristics normally setting the normals become unreliable.

select that polygon and extend your selection with shift +, if it doesn't grow as expected then it means you have duplicate polys around there, in which case just delete and recreate the poly with new poly.

subdividing is also a good way to see if you have double edges like that, because they will obviously pinch a lot and show a ridge that will be a lot harder then expected.

05 May 2006, 10:10 PM
uhm, think you might have misunderstood me.

simply put, i have a hole where i want to put in a polygon, ie the polygon in the pic for example.

however if i created a polygon there, XSI tells me i'll either have to invert all others or go with double edges.

cant have the inverted edges as they wont render right, and cant have the double edges as i cant run edges through em.

so im basically...still pretty stuck here.

05 May 2006, 10:21 PM
1. Select one of the vertices that make up the mal-formed polygon
2. Select Adjacent>Polygon.
3. Deselect the polygons that you don't want to delete with the Raycast Selection mode and see if more than one is selected.
- 3a. If not, delete it. {End}
- 3b. If so you probably have an entire loop of those types of polys.
4. - In that case, select all of the vertices that make up the visible loop {Go to Step 2}

Edit: Additionally you'll probably want/need to weld the points around the affected area.

05 May 2006, 11:10 PM
well, i do that...and delete the mal-formed poly (which wouldve worked just as good by just selecting and deleting it but oh well).

though the problem remains...adding a polygon there still creates a double edge (as i did in the pic) or inverted polys.

now...ive read that its due to it being going in the opposit direction than the previous polygon, or close to opposit atleast. So basically im just being hard to understand.

05 May 2006, 11:27 PM
How are you adding this replacement poly? Trying to use the add poly pen tool thingy? That means paying attention to the direction of creation and all that.

Have you tried just extruding your poly from the edge of an adjacent poly with the correct orientation? Then just weld it all up with the tweak tool set to point weld. Hope this helps.

05 May 2006, 11:33 PM
think that got it....thanks.

05 May 2006, 05:42 PM
It could also be that you have duplicate points that aren't welded.. Select a section of points and make a note of how many points you selected. Modify/Poly/Filter Points. Adjust the slider to 0 and note how many points you have, raise it if necessary

06 June 2006, 01:18 AM
I've often had trouble with the "add polygon" tool for creating a face between edges. I would get the double egdes, or inverted polygons. It warns me of "polygon winding". I find that selecting the verts in a certain order with the add polygon tool gives better results. I have no idea what that order is, just trial and error, and have found no documention on how to properly use the tool, if there is such a way. It seems odd when all the normals of the surrounding faces are the same. For now, it's just an annoyance. In some situations I use the "bridge boundary edges" function, but that often gives undesired results as well. Using the function twice (most of the edges the first time, and remaining the second) works. Still an annoyance. The extrude edge and weld points method works. But there could be a quicker method of welding.

06 June 2006, 11:24 AM
Quite easy just create your new polygon in clockwise ( or anti cloakwise ) all the time and you will never have this alert.

06 June 2006, 05:51 AM
Quite easy just create your new polygon in clockwise ( or anti cloakwise ) all the time and you will never have this alert.

This is a common requirement in every modeling tool I've used. The order in which the polygons are created determines which way the normal will face.

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06 June 2006, 05:51 AM
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