JME3 and Transform Feedback

[deMimsy]

I have discovered I have need to implement transform feedback in my game, and going through the forums I have found that JME3 does not support this functionality. Or rather, all posts I find are from 2012 stating this. I was just wondering has transform feedback been added in, possibly in 3.1? Or has anyone found a work around thus far?

[pspeed]

What is transform feedback? Let’s start there.

What’s the actual effect you are trying to achieve?

[deMimsy]

Hey pspeed, first off, thanks for always being so helpful and quick to respond on these forums.

My intention is to use the geometry shader to perform a calculation on each triangle which is in another equation during each frame. While I have achieved this same thing a while back by just looping through a thread, it has been bogging down my system for a while and needs to be sped up. All calculations are arithmetic, and the thread is already running less than it should be, while models have been reduced down as much as they can. Its just not possible to squeeze anything more through the cpu.

[pspeed]

I think you will have to be more specific, I guess. I’m still not sure what “transform feedback” means or specifically what you are trying to do.

[jmaasing]

I guess from context this is it:
https://www.opengl.org/wiki/Transform_Feedback

[deMimsy]

Yes, Transform feedback is basically the ability to transfer data from the gpu back to the cpu

[pspeed]

@deMimsy

My intention is to use the geometry shader to perform a calculation on each triangle which is in another equation during each frame.

What calculation?

Sometimes when someone asks for something that no one has ever asked for… and it seems strange to ask for it on the surface… we have to wonder about the sanity of the request. It could be that it’s an entirely sane request. It could be that you are doing something strange. We can’t tell from here.

There might be a better/easier way to do what you are ultimately trying to achieve.

I’m just trying to make sure we are avoiding one of these sorts of conversations:

Problem to add texture to a Mesh

@aprouzeau said: Ok I get this now, but how define the index in order to draw a surface passing by all the points defined ? Knowing the fact that I don’t know the coordinates of the points when I write the code. This is starting to feel kind of like a “How do I inject something right into my stomach?” sort of conversation (*). You have already ended up at some strange end place when chances are there were earlier choices to make that would make it a non-issue. Unfortunately, we don’t know wha…

[Momoko_Fan]

Also, don’t forget that geometry shader is essentially a massive for-loop which just happens to be running on the GPU. Due to its nature, it is not parallel like the vertex shader, so you’re not really getting any performance improvement by moving whatever calculations that you’re doing in there.

Easier to just do it on the CPU then.

[deMimsy]

In essence, I would like to recreate the work of this paper for my class:

ISSFD24_Paper_P_Tichy.pdf

So if I am to recreate it, I would like to use the method they provided. It has often been my experience that many are opposed to “injecting food into our stomach” but if we didn’t have people that thought outside the box, we wouldn’t have personal computers, electricity and the sort. Sometimes in trying to do something unintended, we discover more. Maybe a system isn’t meant to do something, but that doesn’t mean it can’t. Moreover, we have found ways to “inject something to the stomach”, gastric feeding tubes have been used a great deal to save people’s lives.