# ConvexHull faces **URL:** \ **Category:** Questions\ **Tags:** geometry\ **Created:** [July 5, 2023, 9:16pm UTC](https://forum.babylonjs.com/t/convexhull-faces/42187 "2023-07-05T21:16:56Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![WillemCramer](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/willemcramer/32/11696_2.png) [@WillemCramer](https://forum.babylonjs.com/u/WillemCramer)\ **Post date:** [July 5, 2023, 9:16pm UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/1 "2023-07-05T21:16:56Z")
With the enormous contribution of @carolhmj I have this ConvexHull going on but there are some things going on that i don’t understand. Focus on the buildRenderableMesh() section from line 379- 421. Probably best have the console open too. Because the convex-hull I did a `this.renderableMesh.forceSharedVertices();` but ended up with way too many faces for the vertices so i tried a `this.faces = this.faces.filter(face => face.mark === 0); ` in line 385. faces are marked with a `const FaceTypes = { VISIBLE: 0, NON_CONVEX: 1, DELETED: 2, }` in lines 425 - 429 Questions: - what to do with the newFaces which are also marked as 0 (visible) - why can’t i set colors to the vertices (mesh turns black) - what’s going on with the faces/facets? when you run the script a couple of times and rotate the mesh you’ll find it’s sometimes perfect and sometimes you see glitches Thanks in advance 🙂 > **[Babylon.js Playground](https://playground.babylonjs.com/#UZWVCC%2344)** > > Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes ---
**Author:** ![Cedric](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/cedric/32/2742_2.png) [@Cedric](https://forum.babylonjs.com/u/Cedric)\ **Post date:** [July 6, 2023, 8:14am UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/2 "2023-07-06T08:14:27Z")
I can answer for the vertex color: you have to push values and not color object. Change visible in this PG: > **[Babylon.js Playground](https://playground.babylonjs.com/#UZWVCC%2346)** > > Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes For the rest, I’ll let @carolhmj 🙂 ---
**Author:** ![carolhmj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/carolhmj/32/25918_2.png) [@carolhmj](https://forum.babylonjs.com/u/carolhmj)\ **Post date:** [July 6, 2023, 3:06pm UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/3 "2023-07-06T15:06:14Z")
The code there is an implementation of the 3D Quickhull algorithm, the original repo has a pdf containing some implementation details and references I used. It’s been a while through so not all the details are clear on my mind anymore 😛 - newFaces should be only part of the hull construction process so you should just be able to ignore it - Cedric already answered that 🙂 - This looks like faces with inside pointing normals that aren’t being marked as deleted, it’s probably a bug in the hull construction code 😅 You could debug it and see where’s that happening, or you could remove these faces after the hull is constructed. ---
**Author:** ![WillemCramer](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/willemcramer/32/11696_2.png) [@WillemCramer](https://forum.babylonjs.com/u/WillemCramer)\ **Post date:** [July 7, 2023, 3:34pm UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/4 "2023-07-07T15:34:28Z")
Thanks for looking into that @Cedric 🙂 I just didn’t know that. And thank you for doing this @carolhmj , you did a great job and I am very grateful! ---
**Author:** ![WillemCramer](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/willemcramer/32/11696_2.png) [@WillemCramer](https://forum.babylonjs.com/u/WillemCramer)\ **Post date:** [July 8, 2023, 7:34am UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/5 "2023-07-08T07:34:57Z")
It’s not perfect yet but it appears to be better 🙂 > **[Babylon.js Playground](https://playground.babylonjs.com/#UZWVCC%2349)** > > Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes ---
**Author:** ![carolhmj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/carolhmj/32/25918_2.png) [@carolhmj](https://forum.babylonjs.com/u/carolhmj)\ **Post date:** [July 10, 2023, 12:54pm UTC](https://forum.babylonjs.com/t/convexhull-faces/42187/6 "2023-07-10T12:54:47Z")
Nice!!! 😄