Tightly packed dynamic uniform buffers

[junglie85]

I want to upload N uniforms each frame and for various reasons need to create each of the uniform buffers on each frame. This is marked as “don’t do” in the wiki, which suggests using a single large buffer. Is there a way to do this without having to adhere to the minimum dynamic buffer offset size?

To give an example, I want to have an API that looks something like this:

gfx.draw_filled_rect(..);
gfx.draw_circle(..);

In my mind I need to generate the vertices and transforms, create the buffers, the bind group and then draw those. The vertex buffer is easy to tightly pack but I don’t know if it’s possible to do so with a single uniform buffer.

Note, I’ve not profiled any of this so a uniform buffer with dynamic offsets and “gaps” in data might be absolutely fine. I’d just like to know what the other options are?

[junglie85]

Thinking about this some more, I'm considering using a uniform pool. This would still mean creating all of the bind groups for each uniform each frame.

I was curious if there were any examples of uniform pools being used and after a bit of searching I found @kvark's baryon crate. It looks like the bind groups are created each frame there too.

However, in response to a question asking how expensive bind group creation is, @cwfitzgerald suggests that making more than a handful of bind groups each frame should be avoided.

Which leaves me uncertain on the merits or demerits of this approach. Is there a general consensus on whether this is a good or bad idea?