Question about b3dm batchId. Why not encode the batchId and index start/end to batch table?

1. A concise explanation of the problem you're experiencing.

I'm trying write a tool to batch mesh with same matereial in gltf file and convert it into b3dm file. But I don't understand the neccessary of putting batchId into vertex attributes. Since it will consume more memory than just put item id and it's start/end index in the batch table. Does anyone has the same question? Correct me if I'm wrong.

2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.
None.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
I am trying to write a pipeline tool to convert gltf to tileset. And I think the first step is to batch meshes in gltf and assign the batchId to each batched mesh. However, I'm a little confused about the neccessary of batchId attributes.

4. The Cesium version you're using, your operating system and browser.
The lastest version.

Any response from you guys is appreciated.
Thank you in advance.

That actually sounds like it would work. I asked around the team and it sounds like this design was just consistent with how things are stored in the batch/feature tables.

If it sounds like it might save a lot of memory, I’d encourage you to try it and open up an issue on the 3d tiles repo (https://github.com/AnalyticalGraphicsInc/3d-tiles/issues) making a case for it. It’s probably not going to change the spec but it might inform future decisions.

I also meant to ask, is this tool you’re working on open source?

在 2019年1月24日星期四 UTC+8上午12:08:02,Omar Shehata写道:

I also meant to ask, is this tool you're working on open source?

That actually sounds like it would work. I asked around the team and it sounds like this design was just consistent with how things are stored in the batch/feature tables.

If it sounds like it might save a lot of memory, I'd encourage you to try it and open up an issue on the 3d tiles repo (https://github.com/AnalyticalGraphicsInc/3d-tiles/issues) making a case for it. It's probably not going to change the spec but it might inform future decisions.

On Saturday, January 19, 2019 at 4:17:59 AM UTC-5, fanqil...@gmail.com wrote:1. A concise explanation of the problem you're experiencing.
I'm trying write a tool to batch mesh with same matereial in gltf file and convert it into b3dm file. But I don't understand the neccessary of putting batchId into vertex attributes. Since it will consume more memory than just put item id and it's start/end index in the batch table. Does anyone has the same question? Correct me if I'm wrong.
2. A minimal code example. If you've found a bug, this helps us reproduce and repair it.
None.
3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
I am trying to write a pipeline tool to convert gltf to tileset. And I think the first step is to batch meshes in gltf and assign the batchId to each batched mesh. However, I'm a little confused about the neccessary of batchId attributes.
4. The Cesium version you're using, your operating system and browser.
The lastest version.
Any response from you guys is appreciated.
Thank you in advance.

Thanks for you reply. I opened up a issue here. https://github.com/AnalyticalGraphicsInc/3d-tiles/issues/366.
The tool I'm building now is in my private repo now since the major party is not finished yet. But I will change it to a public repo as soon as I think it's ready. Thanks again.