How to add normals and UV data?

[dev20240517]

var mesh = new DracoMesh();
var attrPos = PointAttribute.Wrap(AttributeType.Position, controlPoints);
mesh.AddAttribute(attrPos);
mesh.Indices.AddRange(indices);

How to add normals and UV data?
Use the following method to compress errors.

var attrNormal = PointAttribute.Wrap(AttributeType.Normal,1, normals.ToArray());
mesh.AddAttribute(attrNormal);

[lexchou-aspose]

Here's an example to add normal data:

        Vector3[] normals = new Vector3[]
        {
                new Vector3( -1, 0, 0f),
                new Vector3( 1, 0, 0f),
                new Vector3( 0, 1, 0.0f),
                new Vector3( 0, 1, 0f),
                new Vector3( 0, 0, 1.0f),
                new Vector3( 0, 0, 1.0f),
                new Vector3( 0, 0, -1.0f),
                new Vector3( 0, 0, -1.0f)
        };
        Vector2[] uv = new Vector2[]
        {
                new Vector2( -1, 0f),
                new Vector2( 1, 0f),
                new Vector2( 0, 1),
                new Vector2( 0, 1),
                new Vector2( 0, 1.0f),
                new Vector2( 0, 1.0f),
                new Vector2( 0, -1.0f),
                new Vector2( 0, -1.0f)
        };


        var attrNormal = PointAttribute.Wrap(AttributeType.Normal, normals);
        mesh.AddAttribute(attrNormal);

        var attrUV = PointAttribute.Wrap(AttributeType.TexCoord, uv);
        mesh.AddAttribute(attrUV);

In the default case it's identity mapping, which means the number of normals/UV should be the same to the position data.

If you want to manually map the entry to specified position point, you can use following code:

        attrUV.SetExplicitMapping(controlPoints.Length);
        attrNormal.SetExplicitMapping(controlPoints.Length);
        for (int i = 0; i < controlPoints.Length; i++)
        {
            attrUV.SetPointMapEntry(i, 0);
            attrNormal.SetPointMapEntry(i, 0);
        }

[dev20240517]

var mesh = new DracoMesh();
var attrPos = PointAttribute.Wrap(AttributeType.Position, controlPoints);
mesh.AddAttribute(attrPos);
mesh.Indices.AddRange(indices);

var attrNormal = PointAttribute.Wrap(AttributeType.Normal, normals);
mesh.AddAttribute(attrNormal);

var drcBytes = FileFormat.Drako.Draco.Encode(mesh, encodeOptions);

Why is adding normal compression after adding vertices and indexes incorrect?
Is there any other way to add vertices, indexes, and normal at the same time?

System.IndexOutOfRangeException

[lexchou-aspose]

Can you provide full code sample to reproduce this?

I have updated the test case with a working code.

[dev20240517]

I have found the cause of the problem.
NumPoints were not assigned a value, and I thought it would automatically be based on the passed AttributeType Position calculation;
I have now assigned NumPoints and the compression has been successful;
Thank you very much for your patient answer!!!

[lexchou-aspose]

Good to hear that.

This strange unnecessary requirement was inherited from the original draco implementation.

I'll update this behavior in the next version.