Reader/Writer for Instanced 3DTiles (i3dm)
i3dm specs:
https://github.com/CesiumGS/3d-tiles/tree/master/specification/TileFormats/Instanced3DModel
https://www.nuget.org/packages/i3dm.tile/
Reading i3dm. Supply the i3dm filename.
var i3dmfile = File.OpenRead(@"test.i3dm");
var i3dm = I3dmReader.Read(i3dmfile);
The i3dm object contains the glTF, FeatureTable (for instance Positions, NormalUps, NormalRights, ScaleNonUniforms, Scales) and BatchTable information.
Writing i3dm. Supply the GLB (as byte[]) and instance positions (as list of Vector3). Optionally instance NormalUps, NormalRights, Scales and ScaleNonUniforms can be provided.
var i3dm = new I3dm.Tile.I3dm(positions, glb);
var bytes = I3dmWriter.Write(i3dm);
When writing an i3dm, also an external url can be provided to the glTF model instead of embedding the glTF in each tile:
var glbUrl = "http://myserver/test.glb";
var i3dm = new I3dm.Tile.I3dm(positions, glbUrl);
var bytes = I3dmWriter.Write(i3dm);
Batch Id's are written in the FeatureTable by default as type 'UNSIGNED_SHORT', sample to use 'UNSIGNED_BYTE':
var batchIds = new List<int>() { 0, 1 };
var i3dm = new I3dm.Tile.I3dm(positions, glb);
i3dm.BatchIds = batchIds;
var bytes = I3dmWriter.Write(i3dm, "UNSIGNED_BYTE");
BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19041.329 (2004/?/20H1)
Intel Core i7-9750H CPU 2.60GHz, 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=3.1.301
[Host] : .NET Core 3.1.5 (CoreCLR 4.700.20.26901, CoreFX 4.700.20.27001), X64 RyuJIT
DefaultJob : .NET Core 3.1.5 (CoreCLR 4.700.20.26901, CoreFX 4.700.20.27001), X64 RyuJIT
| Method | Mean | Error | StdDev | Gen 0 | Gen 1 | Gen 2 | Allocated |
|---------- |-----------:|---------:|---------:|---------:|---------:|---------:|----------:|
| ReadI3dm | 163.4 us | 1.79 us | 1.59 us | 111.0840 | 111.0840 | 111.0840 | 359.43 KB |
| WriteI3dm | 2,208.6 us | 41.15 us | 36.48 us | 109.3750 | 109.3750 | 109.3750 | 418.31 KB |
Not implemented (yet):
- quantized and oct encoded properties
QUANTIZED_VOLUME_OFFSET, QUANTIZED_VOLUME_SCALE, POSITION_QUANTIZED, NORMAL_UP_OCT32P, NORMAL_RIGHT_OCT32P
- System.Text.Json
2020-11-04 - 0.5: Breaking change: void I3dmWriter.Write(string path, I3dm i3dm) -> byte[] I3dmWriter.Write(I3dm i3dm)
2020-11-02 - 0.4.2: add write to stream
2020-11-02 - 0.4.1: add support for composite tiles (cmpt)
2020-10-19 - 0.3.3: add support for external glb (gltfFormat == 0)
2020-08-27 - 0.3.2: add support for rtc_center for high precision positions
2020-07-01 - 0.3.1: adding 8 byte padding requirements
2020-06-29 - 0.3: adding FeatureTable batchIds formats (unsigned byte, unsigned short, unsigned int), scale and rtc_center
2020-06-25 - 0.2: Adding writing i3dm tiles
2020-06-22 - 0.1: Initial version - reading i3dm tiles