Hi, I am trying to extrude a polygon that gets its data from GEOJson, and is then converted to XYZ (with Z being all 0s). When i try to extrude using:
const polygon_triangulation = new BABYLON.PolygonMeshBuilder(“zgrada”, points);
const polygon = polygon_triangulation.build(false,1);
I get this weird visual bug where the sides are only visible when you are NOT looking at them directly, or maybe it isn’t a bug I dont know.
bumb bump ahh
I think a PG may help understand better
Wait let me get the data right then, I would have posted it at first but it uses GEOJson data that it converts from unprojected to projected, so the X’s and Y’s end up in 5 million range.
Anyway @Danilo_Vukovic , ensure that your Vector Path is build in Counter Clockwise order (CCW).
I had a similar issue and it was due to the wrong order (CW).
Path for poligon should be counterclockwise, there code, to reverse path if it is not so
private insurePathIsCounterclockwise(path: Array<Vector2>): Array<Vector2> {
if (this.isCounterclockwise(path)) return path;
return path.reverse();
}
private isCounterclockwise(path: Array<Vector2>) {
if (path.length < 3) return false;
let sum = 0;
const minx = [...path].sort((a, b) => a.x - b.x)[0].x;
const miny = [...path].sort((a, b) => a.y - b.y)[0].y;
path = path.map(x => new Vector2(x.x + 1 - minx, x.y + 1 - miny));
for (let i = 0; i < path.length; i++) {
const iNext = (i + 1) % path.length;
const point = path[i];
const pointNext = path[iNext];
sum += (pointNext.x - point.x) * (pointNext.y + point.y);
}
return sum < 0;
}
Hi Danilo,
Welcome to the BJS community. I can’t see your code, only screenshot but from what I see and your description of ‘cannot see sides when looking directly at them’, there’s a fair chance of a simple answer (nothing related with the way you build or import your points). It looks to me that either
As far as I know, this builder closes path loop by itself, so it actiually would be a great idea to delete last point of path if it is the same point as first one.
As far as I know, I experienced it and it didn’t work this way.
I have just been doing a post with a couple of faulty examples in the doc and playground examples.
I’m updating the post just know as i keep on finding new ones with the same issue.
Edit: but you’re right saying that not all constructors (mesh builders) act the same. And this is also kind of annoying, isn’t it?
There three ways to extrude polygon:
MeshBuilder.ExtrudeShape() // Worst one for me.
MeshBuilder.ExtrudePolygon() // No way to add arcs.
new PolygonMeshBuilder("name", path).build(updateble: false, length: 1) // The one's that Danilo use.
First and second do not close loop. Last one does.
I believe that author of topic creates simple forms of buildings from gis data.
So my reply is refers to that.
For creating a rope it is better to use second method, I think 
.
Oh Thank you for this post,
A nice resume of the current situation,
I’d like the doc to be as explicit in this aspect.
Food for thoughts, I suppose, 
sorry, 'just realized that the rope playground example use ‘.ExtrudeShape’ and this is precisely one method that requires you to close the path/shape if you don’t want a glitchy output (as shown in the faulty examples).
Again, In my understanding of the doc I would have said the same as you, but, in truth, this is not the case. In the end, .ExtrudeShape requires you to close the path. Or else, I should quickly go and have my eyes checked 
Thank you all for your responses. Turns out a simple points.reverse() fixed the problem. I had no idea that GeoJSON polygon data was in clockwise format, I just guessed it would play along nicely. The output is the same whether or not i .pop() the last closing point or not.
Thank you!!