Unable to update Normals with mesh.updateVerticesData

Questions
1

Hey there,

I am importing a glb file that contains no normal data. I want to calculate the normals in babylon and assign it to the mesh. I do that with the following lines:

let normals = [];
BABYLON.VertexData.ComputeNormals(positions, mesh.getIndices(), normals, {useRightHandedSystem: true});
mesh.updateVerticesData(BABYLON.VertexBuffer.NormalKind, normals);
mesh.markVerticesDataAsUpdatable(BABYLON.VertexBuffer.NormalKind, false);

When I now log mesh.getVerticesData(VertexBuffer.NormalKind) I get null as output.

I also tried assigning new normals to a mesh from a glb file that contains normal data. When I log the normals after I assigned them I still get the old normals that were in the glb file.
Updaing positional VerticesData works fine tho.

I am not sure if there is a problem with the normals that I want to assign or the updateVerticesData function not used correctly.

Here are some of the normals that get calculated by babylon, that I want to assign to the mesh:

[4.598461638259964e-8, -0.7071067827039836, 0.7071067796691101, -1, 0, 0, 4.598461638259965e-8, -0.7071067827039836, 0.7071067796691101, 0.9999999999999906, 0, -1.3734263967059612e-7, -2.791149088641237e-16, -1, -4.291957489706169e-9, -1, 0, 0, -6.503207674669478e-8, 0, -0.9999999999999979, -2.791148907127026e-16, -1, -4.29195748970615e-9, 0.9999999999999906, 0, -1.3734263967059612e-7, -6.503207674669478e-8, 0, -0.9999999999999979, -0.6666666533519996, 0.6666666750293564, 0.3333333432372876, 0.4082483522344218, 0.4082482991359628, 0.8164965457063936, -0.4082483358807086, 0.4082482827822415, -0.8164965620601127, 0.6666666355483176, 0.6666666572256821, -0.33333341445198894, 0.4658385042362787, 0.7045829703247973, -0.5353104948524661, 0.40627880861137067, 0.035627481733082576, -0.9130543314713995, 0.9133802539951988, 0.0760896417581252, -0.3999335920234584, 0.723294597665292, 0.6904839016060469, 0.008769641446170878, 0.053586574217419886, 0.6812205246593184, -0.7301144265432123, -0.483543019468095, 0.6553851676893931, -0.5802210184890095, -0.7811584367611728, 0.6220898721199501, -0.05287426295112553, -0.771131441152216, 0.07102471669275595, -0.6327019757241322, -0.46524072192735405, 0.04074604246381047, -0.8842459107533672, -0.053588173468265166, 0.6387104142149294, -0.7675788652885961, 0.9967044283638481, 0.07887743312790357, -0.018937608694023833, -0.9945753404905061, 0.05237297133617486, -0.08987193088842672, 0.06897289481220718, 0.9857895685164555, -0.15317201567311362, -0.06951776485470834, 0.9857133384975062, -0.15341608350399988, 0.07581344412774046, 0.07615872803738986, -0.9942093189229403, -0.06513717945492956, 0.06554271052769509, -0.995721497683634, -0.0000028633006379925027, 0.9844924626213138, -0.17542688230035486, 0, 0.9881413108455315, -0.15354722335644816, 0, 0.07974854530083796, -0.9968150126891149, 0, …]

Thank you for your help!

2

I think the problem is that updateVerticesData returns early without doing anything if the buffer doesn’t exist already or if it isn’t updatable, but if you use setVerticesData it will create a new buffer for you and set it regardless. Try doing it like below. :slight_smile:

let normals = [];
BABYLON.VertexData.ComputeNormals(positions, mesh.getIndices(), normals, {useRightHandedSystem: true});
mesh.setVerticesData(BABYLON.VertexBuffer.NormalKind, normals);
3

Awesome that solves my issue!

I still wonder why I couldnt update the normals when I used a glb file that contained normal data…

4

Probably the existing buffer is set as not updatable so updateVerticesData can’t update it and so setVerticesData is needed to create and set a new buffer. :slight_smile:

EDIT: and if you pass true as the third argument to setVerticesData then you should be able to later call updateVerticesData to update it (this 3rd parameter, updatable, defaults to false).

5

Nice, good to know. Thank you very much