public void ComputeNormals()
{
var builder = new MeshBuilder(false);
builder.AddPolygon(new List<Vector3>
{
new Vector3(0f, 0f, 0f),
new Vector3(7f, 0f, 0f),
new Vector3(7f, 0f, 7f),
});
Assert.IsNull(builder.Normals);
Assert.IsFalse(builder.HasNormals);
builder.ComputeNormalsAndTangents(MeshFaces.Default);
Assert.IsTrue(builder.HasNormals);
Assert.AreEqual(3, builder.Normals.Count);
}